Vray

V-Ray 1.52 for trueSpace7.5........................................................................................ 3 1. QuickStart Tutorial.............................................................................................. 5 1.1 Workspace ........................................................................................................ 5 1.2 Model ............................................................................................................... 6 2. Workspace Rendering Tools ............................................................................... 8 2.1 Scene Render Command: ................................................................................. 8 2.2 Area Render Command: ................................................................................... 8 2.3 Object Render Command: .............................................................................. 10 2.4 Save to File:.................................................................................................... 10 2.5 Render to File: ................................................................................................ 10 3. Rendering Workspace animation in Model ..................................................... 12 4. Materials ............................................................................................................. 14 4.1 Material Editor Tools ..................................................................................... 15 4.2 Static vs. Live version of Material Editor ...................................................... 16 4.3 Shader selection.............................................................................................. 17 4.4 V-Ray Material Libraries ............................................................................... 19 4.5 Color Shaders: ................................................................................................ 20 4.6 Bump / Normal / Displacement Shaders: ....................................................... 21 4.7 Transparency Shaders: ................................................................................... 21 4.8 Reflectance Shaders: ...................................................................................... 21 5. V-Ray Shaders .................................................................................................... 23 5.1 Glossy Reflection Shader ............................................................................... 23 5.2 Fresnel Reflection Shader .............................................................................. 25 5.3 Sub-surface Scattering Shader ....................................................................... 27 5.4 Hair / Fur displacement Shader ...................................................................... 34 6. V-Ray Options and Parameters ........................................................................ 37 6.1 View ............................................................................................................... 38 6.2 Lights.............................................................................................................. 38

7. Global Illumination ............................................................................................ 43 7.1 GI Parameters ................................................................................................. 45 7.2 GI Notes and Tips: ......................................................................................... 53 8. Caustics ............................................................................................................... 57 8.1 Caustics Settings ............................................................................................ 57 9. Save and Load Irradiance, Light, and Photon maps ...................................... 59 9.1 Map Settings................................................................................................... 59 9.2 GI Maps Notes and Tips: ............................................................................... 59 10. Depth of Field ................................................................................................... 61 11. Rendering Options ........................................................................................... 63 11.1 General Rendering Settings.......................................................................... 63 11.2 Background .................................................................................................. 65 12. HDRI ................................................................................................................. 66 12.1 HDRI Settings .............................................................................................. 66 12.2 HDRI Examples ........................................................................................... 67 12.3 HDRI Notes and Tips ................................................................................... 68 13. TUTORIALS .................................................................................................... 69 13.1 Quick and Simple ......................................................................................... 69 13.2 Soft Shadows ................................................................................................ 70 13.3 HDRI for Reflection Only ............................................................................ 70 13.4 Full HDRI ..................................................................................................... 72 13.5 Caustics ........................................................................................................ 73 13.6 Global Illumination ...................................................................................... 75 13.7 Combining Global Illumination and Caustics .............................................. 75 13.8 Combining Caustics and HDRI .................................................................... 76

V-Ray 1.52 for trueSpace7.5 V-Ray is a render engine written by Chaos Group (www.chaosgroup.com). It is well known, especially for its blazing speed as well as an extensive array of global illumination methods that can produce very high quality renderings.

Box object by Mike Harris, Head by Steve Britton

V-Ray rendering support is implemented as a trueSpace 3rd party render engine, and is fully integrated into both the Workspace and Model aspects. Scene, Object, and Area rendering are all supported and accessed using the same Model icons as for Lightworks and Virtualight., so that no changes in workflow are required, but V-Ray-specific tools and icons are also available in Workspace. Materials can be edited in the Material Editor, which gives a direct preview of the material rendered in V-Ray so that you can accurately see the effect of changing the material parameters. The Workspace Material editor means you no longer have to jump to Model to make surfacing changes.

Abstract fractal geometry by Marcel Bartel

There is one important aspect where V-Ray support differs from other trueSpace render engines - even though the user interface is fully integrated into the Modeler aspect, V-Ray support is based on the contents of the Workspace in trueSpace. The scene description (geometry, lights, and materials) is taken from the Workspace scene graph, so rendering relies on the Bridge between the Modeler and the Workspace for scene synchronization. With the addition of the Workspace Material Editor, you can now choose to work exclusively in Workspace, thereby avoiding any Bridge conversion issues.

1. QuickStart Tutorial 1.1 Workspace 1. Start trueSpace. 2. Setup the scene (alternatively, you can load a scene from any Workspace library)

3. Press the V-Ray Render Scene icon: 4. The V-Ray Render View window will open and display the scene as it is rendered (Note that instead of rendering scanlines, V-Ray renders “buckets” which show as rectangular areas of the image. This gives a better (faster) preview of the result than regular scanline rendering.) 5. Although this gives you your first quick V-Ray render, for optimal results you will need to set up the lights, materials and rendering preferences so that they are specifically tailored for VRay.

A simple first V-Ray render using a Workspace library scene

1.2 Model 1. Start trueSpace. 2. Setup the scene (alternatively, you can load a scene from the VRay library which can be loaded from the trueSpace Scene library icon) 3. Open the Preferences panel in Modeler. 4. Choose the V-Ray.tsr from the drop-down box (as seen below)

5.

Render the scene by clicking on the “Render Scene” button. (Note that instead of rendering scanlines, V-Ray renders “buckets” which show as rectangular areas of the image. This gives a better (faster) preview of the result than regular scanline rendering.)

6.

Although this gives you your first quick V-Ray render, for optimal results you will need to set up the lights, materials and rendering preferences so that they are specifically tailored for VRay.

A simple first V-Ray render using one of the trueSpace V-Ray library scenes

2. Workspace Rendering Tools Familiar rendering commands are now available in Workspace, as seen below:

2.1 Scene Render Command: Left-click on V-Ray Scene Render button will start V-Ray rendering, opening the V-Ray Render View and showing the progress of the render. Note that it is possible to dock Vray view. You can save your image after it has rendered, see Save to File below. 2.2 Area Render Command: Area render command allows you to select the rendering rectangle prior to the actual rendering – thus you can render only the relevant portion of the view getting the rendering preview faster. The intended workflow is as follows: Start area render tool Draw a rectangle in 3D view to define the rendering rectangle Render will start when you release the mouse after drawing the rectangle

3D View with area render rectangle drawn

Docked VRay Render View with SaveToFile button

2.3 Object Render Command: The same functionality as in the case of scene render except only selected objects will be rendered. 2.4 Save to File: It is possible to save any rendering (even incomplete) to image file. Left-click this button in the Render View titlebar, and select the image filename from the resulting dialog box. JPEG, PNG, BMP and HDR formats are supported. 2.5 Render to File: You can render out a scene to an image file, or an animated scene to a series of images or as an AVI file by left-clicking this button. Doing so will bring up the output dialog (this example taken from a computer running Windows Vista):

Output frames: You may render the a single image of the scene or Current Frame Only of an animated scene, All Frames of the animation, or just a Selection. The length of the All Frames option is determined by the settings in the Animation Editor Filename: Enter the name of the file you wish to output, e.g. c:\images\render.avi. As well as .AVI movie files, various image formats are supported (.BMP, .TGA, .PNG, .JPG, .HDR), in which case

trueSpace will automatically add the frame number, giving you render0000.bmp through render0030.bmp for example. When rendering to AVI files, you will be presented with a dialog box to choose which video compressor to use before the first frame is rendered. The available choices are dependent on what video codecs you have installed on your system, and you should be aware that some codecs mandate particular output sizes, such as width and height having to be divisible by 4. Rendering will be aborted if a frame can not be output to the AVI, so if you are trying to render an animation and only the first frame is output, there is an incompatibility with the codec you are using.

3. Rendering Workspace animation in Model Animation created in Workspace can be rendered using any of the rendering engines in Model, including V-Ray. The workflow is the same – just hit Render to File – with just one small addition to the output dialog, the ability to change between Workspace and Model under Animation:

Render to File Dialog in Model

When Workspace is selected, the frame range and frame rate information is synchronized from Workspace, otherwise it is taken from Model. Note that as Model relies on the Bridge to synchronize information every frame, if a feature or object is not supported it will not appear in Model and thus will not be rendered in the animation.

4. Materials Materials for V-Ray can still be edited in the Material Editor in the Modeler aspect, just as they are for Lightworks and the other render engines, and the Material Editor includes the preview of the material rendered under V-Ray. Note that the Material Editor will close if you change render engines – this is to allow the preview window for the Material Editor to change from one render engine to another. It is now preferable to use the Workspace Material Editor, particularly if you are working with the animation tools. Now all animation, surfacing, and rendering can be performed on the Workspace side, without having to go through the Bridge. More information about using the Workspace Material Editor with non-V-Ray materials may be found in the main trueSpace documentation.

Location of the Material Editor tools in Workspace View3D toolbar

Material Editor Panel

4.1 Material Editor Tools  

Paint Object:  Assigns material active in Material Editor to all selected objects. Paint Face:  Starts a tool to assign material active in Material Editor to individual faces. Face can be selected either by left-clicking on it or by left-click & drag – in that case all faces which mouse moves over them will be painted by the active Material Editor material. If there is a face selection associated with the object at the time of a mouse click all selected faces will be painted. 



The tool is active while paint face cursor is active – you can can disable it by right-clicking anywhere in the 3D view. Paint Over:  Starts a tool to repaint a material on object with the material active in Material Editor. The material to replace is selected by left-clicking on any face of the object being painted by a particular material. Note that the change of the material is propagated throughout the hierarchy of the selected object. 

The tool is active while paint over cursor is active – you can disable it by right-clicking anywhere in the 3D view.



Inspect:  Starts a tool to acquire material from object and make it the active material in Material Editor. Left-click on any face using a particular material you want to make active in Material Editor. 



The tool is active while inspect cursor is active – you can disable it by rightclicking anywhere in the 3D view. Reset: you can return to the default material easily. Right-click on any of the tool icons and select “Reset”. The default shaders with default parameters will be selected into the Material Editor for each shader type.

4.2 Static vs. Live version of Material Editor The default (static) version of Material Editor doesn't provide live update of individual shaders – only the material preview is updated. This gives an increase in performance when using the Material Editor. The shader spheres in this case are just placeholders for access to functionality of individual shaders. It is possible to switch Material Editor to “Live” aspect – in this case the individual shaders are updated as the shader parameters are modified.

Static version – shader previews are static images showing 4 individual channels of the material

Live version with updated preview of shader spheres

When using the live version of the Material Editor it is possible to switch between sphere and plane primitives for material/shaders previews by right-clicking on the individual preview panel.

Material, color and transparency channels with plane preview

4.3 Shader selection  Individual shaders can be loaded into Material Editor from V-Ray shader libraries  To open V-Ray Shader library double-click the respective shader preview in Material Editor. Shader library is opened bellow Material Editor and it can be closed at any time...  Double-click shader item in the library to load it to Material Editor. The new shader will appear and Material Editor will refresh accordingly.

The regular mapped shaders (texture map, transparency map, bump map, normal map) use a bitmap control-based interface instead of forcing user to rely on image paths (thus better preview of the map being used). The maps can either be loaded from Bitmap library, by using CTRL+double-click to bring up a traditional file dialog, or by using the file picker button.

4.4 V-Ray Material Libraries

V-Ray materials can be stored in a material library. The library can be opened from Library browser.

V-Ray materials library in Library browser

A V-Ray material library appears in the library stack view like any other.

V-Ray materials library

To add a material to a material library, do any of these:  Select the object painted with the material you want to add, right-click in material library and select “Insert”  CTRL-click on the object with the material you want to add and drag it to the library  With the Material Editor open, right-click in material library and select “Insert” To apply material from library:  Drag & drop a material from the library to the object  Double-click the material in the library and the material is applied to all selected objects  With the Material Editor open, double-click the material and it will be selected into the Material Editor Notes and Tips: Because the Material Editor opens in the stack view, you may find it convenient to open your V-Ray material libraries in the workspace itself. To do this, open your material library as normal, then drag the window into the workspace while holding down the CTRL key. Then you can choose materials while still keeping the Material Editor open. 4.5 Color Shaders:

Plain and texture-based shaders are supported directly. All other color shaders (that is, the procedural shaders) are sampled and mapped as textures automatically – this process works by rendering an image of the shader in Lightworks, and using this as a texture in V-Ray for rendering, with no need for any intervention by the user.

4.6 Bump / Normal / Displacement Shaders: Only two displacement shaders are supported - the Bump Map shader (which uses a texture as a bump map), and the Normal Map shader. All other shaders (that is, the procedural shaders) are not supported. There is one more special V-Ray shader for simple hair/fur rendering. Documentation for this shader is found with the rest of the custom V-Ray shaders below.

4.7 Transparency Shaders: Only two transparency shaders are supported – the Plain transparency shader, and the Transparency Map shader. All other shaders (that is, the procedural shaders) are not supported.

4.8 Reflectance Shaders: V-Ray supports some shaders that also work under Lightworks. There are also some shaders supported under Lightworks that cannot be used with V-Ray, and some shaders that can only be used with V-Ray. Those shaders which cannot be used under V-Ray will appear as grayed out in the list of available shaders to show that they are unavailable for use. Those shaders which are supported under V-Ray as well as under Lightworks are Phong, Caligari Phong, Metal, Caligari Metal, Plastic, Matte, Mirror, Glass, Conductor, Dielectric, Wrapped Mirror Map, Mapped Phong, and Mapped Metal. Please see the documentation for these shaders under Lightworks, as all parameters will work in the same way under V-Ray. Exceptions are noted below. Wrapped Mirror Map, Mapped Phong, Mapped Metal In Lightworks, using a texture map with these shaders completely overrides the slider value for the diffuse, specular, etc. channels, but V-Ray instead multiplies the slider value with the result of the texture look-up. This gives better control over the surface, particularly when using the Workspace Material Editor where you can edit the numerical value and the texture map at the same time, but if you wish to duplicate the Lightworks behavior simply ensure you set the numerical value of the channel you wish to affect to 1.0. Here is an example of the Mapped Phong shader in action, providing varying amounts of transparency/transmission of an etched glass surface, with soft shadows working correctly:

By Jack Edwards

Metals versus Plastics To accurately reproduce real-world materials, we need to think about distinguishing characteristics. Metallic surfaces should show reflections and specular highlights (which are actually just simulated reflections) as variations of the base color, while plastic materials generally do not do this. Previously, V-Ray treated all reflective surfaces as metal, but now V-Ray will automatically choose the correct algorithm based on your choice of reflectance shader. Caligari Metal, Dielectric, Mirror, Mapped Metal, and Glass will all use the metal-type reflections, while Caligari Phong, Fresnel, Glossy, and Mapped Phong all use the plastic-type reflections. If you are trying to duplicate a Lightworks material and are having trouble seeing reflections on dark colors, it is likely you are using Mirror, so you should switch to a plastic-type shader such as Caligari Phong. Those shaders which are unique to V-Ray will appear as grayed out when any render engine other than V-Ray is selected. Full details of these shaders, including descriptions of their parameters and usage, are given below.

5. V-Ray Shaders 5.1 Glossy Reflection Shader The Glossy shader allows for blurred reflections and refractions, and is ideal for creating materials that are not perfect reflectors and are not perfectly transparent. This would include objects which are reflective but have a rough surface, such as brushed metal, or those which are not highly polished and only slightly reflective, such as a regular table top or wooden floor. It is also ideal for objects which are transparent but rough, such as frosted glass, or those which are still quite opaque, such as plastic.

Soft or blurred reflection and refraction is the hallmark of the Glossy Reflection shader (by Saul Cross)

The Glossy shader is available in the Reflectance Shader Library (but only if the V-Ray render engine is enabled; the shader will appear grayed out and disabled for the Lightworks and Virtualight render engines).

General parameters: These function the same way as in the Caligari Phong shader, please see the documentation for that shader for details. Refl. Gloss.: This controls the glossiness of the reflections. Low values mean a very polished surface with a very sharp reflection, while higher values mean a less polished surface with reflections being more blurred and softer. Refr. Gloss.: This controls the glossiness of the refraction. Low values mean a very glass-like surface with very sharp refractions, and higher values mean refractions being more blurred and softer. Subdiv: The number of samples to take when approximating the glossy reflection/refraction. A higher number of samples will reduce noise, but increase render time.

Glossy Shader panel

Spheres with varying glossiness (from left to right, values of 0., 0.2, 0.4, 0.6, 0.8)

Notes and Tips: Begin your tests with a low Subiv value (in the range 3-5) to get the feel for the reflection.  Only add more samples afterwards, when ready to do a final render, as they are costly in calculation time and slow down the rendering. A Subdiv value of 1 or Glossiness value of 0 will result in perfect specular  reflection/refraction, making it identical to using the Caligari Phong shader.

Glossy refraction makes the glass object look like plastic, while glossy reflection gives the can a brushed metal appearance (Wert objects by Mike Harris)

5.2 Fresnel Reflection Shader In many simple shaders, reflections and refractions are at a constant intensity over the surface of an object. In the real world, the brightness of reflection and refraction varies depending on how the surface is angled to the viewer – reflections become less intense when the surface is facing the viewer, while refraction (the ability to see though the object) becomes brighter when the surface is facing the viewer. The Fresnel Reflection shader includes these effects, which can allow for much more realistic objects, particularly for metal and glass materials, for example. As well as creating a realistic effect in the refraction, the shader also creates transparent shadows that take Fresnel equations into account.

Image with regular metal and glass shaders

Image using the Fresnel shader the objects

As well as allowing mathematically correct real world effects, the shader also allows you to override the real world settings to give a more exaggerated (or more subtle) effect than is normally seen, for more flexibility in the results. The images above illustrate the differences between regular raytraced reflections and refractions, and when the Fresnel shader is used (with exaggerated settings, and an oversized wine glass, used here to illustrate the effects more clearly). In the image on the left, the reflections and refractions are constant in intensity over the surfaces of the objects. In the image on the right however, those surfaces which face the viewer (for example, the middle of the sphere) show reduced reflection compared to surfaces which are sharply angled to the viewer (for example, at the edges of the sphere). This gives the sphere a bright edge, and the same effect can be seen on the trumpet. Although exaggerated in this example to make the effect more obvious, even when used more subtly it still adds realism to the scene (duplicating effects seen in the real world) and gives the eye extra visual cues about the shape and form of objects. In a similar way, the glass also shows variation in reflection, but also in refraction (this is the reverse of reflection, where surfaces facing the viewer are more transparent and show more effect from refraction, while those at sharp angles to the viewer such as at the edge of the glass show less transparency and appear more solid and less easy to see through). The final element to note is the shadow of the glass, which is no longer a constant shadow but varies depending on the shape of the object the light has passed through.

Weight : The strength of the Fresnel effect. A higher value will make variation in the reflections, refractions and shadows more obvious. Angle : When unchecked, physically correct real world values are used for the Fresnel effect. When checked, physically correct values are overridden and the value in the Angle box is used instead, to give user-control over the result. A low value will result in a sharp transition to low reflection/high transmission at the objects edges (when the surface is pointing at a sharp angle to the viewer rather than at the viewer, called the grazing angle). This will limit the effect to the edges of the object. Higher values will mean a more gradual transition, meaning the effect will still be obvious even toward the center of the object, away from the edges. A value of 0.2 will approximate the physically correct Fresnel coefficient. Fresnel Shader panel

Internal Reflect. : If enabled, additional rays will be traced in order to correctly calculate internal reflections. When checked rendering will be slower, but the result will be more realistic.

5.3 Sub-surface Scattering Shader Sub-surface scattering is the name given to the effect when light does not simply bounce off the surface of an object, but instead penetrates inside the object for a limited depth and bounces around inside the material. The end result is that when light falls on a particular part of the surface, other areas nearby also become illuminated, but from the inside. Also, an object may be lit “from the back” where light passes through the object to illuminate it. This effect is most widely seen in materials such as marble, jade, wax, translucent plastic, paper, parchment, and skin, and this shader is ideal for use when those materials are required. Prime examples of this effect are when shining a flashlight through the skin on your hand, when looking at a candle (where the wax seems to “glow” from the light of the flame), or a lampshade illuminated by the light passing through it from the inside.

Without Sub-surface scattering, only direct lighting can illuminate object, so the candle and parchment appear black.

Adding Sub-surface Scattering to the candle and parchment allows them to be lit from behind, including the Caligari texture on the parchment – note also the colored shadow from the glass on the parchment.

The head on the left has no sub-surface scattering – the addition of sub-surface scattering helps achieve the look of jade or marble

The sub-surface scattering effect is generated as a combination of 2 separate light transport mechanisms: Single scatter approximation: This approximates the effect of a single scattering event in the material – that is, light enters the object, is scattered once, and then leaves the object in the point being shaded. Diffusion approximation: As the light tends to become isotropic (uniform in all directions) after several scatterings in the material, all higher-order scattering effects after the first are approximated using diffusion approximation. This handles the effect of light entering the object in one place and illuminating other points in close proximity. The difference in the two effects can be seen in the images which are shown below for each of the parameters. Sub-surface Scattering panel

Extinct. S : This controls the extinction coefficient of the material for the single scatter approximation, and larger values mean less scattering (more absorption) in the material.

Extinct S values of 0.75, 1, 2 and 8 (no diffuse approximation used in these images)

Weight S : This controls the strength for the single scatter approximation effect. Higher values make the subsurface scattering effect more visible.

Weight S values of 1, 0.75, 0.35, and 0 (no sub-surface scattering)

Extinct. D : This controls the extinction coefficient of the material for diffusion approximation, and larger values mean less scattering (more absorption) in the material.

Extinct D. values of 0.5, 1, 2 and 16 (no single scatter approximation used in these images)

Weight. D : This controls the strength of the diffusion approximation effect. Higher values make the subsurface scattering effect more visible.

Weight D values of 1, 0.75, 0.5, and 0 (no sub-surface scattering)

Subdiv : This controls the number of samples to take when calculating sub-surface scattering effects (0 means no subsurface scattering). A higher number of samples will reduce noise, but result in longer render times. Note that for Single Scatter approximation, higher values will help the effect respond more accurately to the geometry, while for Diffuse approximation it will reduce the noise in the result. Depending on your objects, you may need a higher Subdiv value to achieve a good Single Scatter result than you require for the Diffuse approximation result (see images below).

Single scatter approximation only, with sample values of 2, 4, 8 and 32 – note how higher samples allows the effect to respond more accurately to the geometry, particular on the lips

Diffuse approximation only, with samples of 1, 2, 4 and 8 – note how higher samples reduce noise for diffuse approximation, a different result than seen with Single Scatter approximation

The Sub-surface Scattering Shader is available in the Reflectance Shader Library (but only if the V-Ray render engine is enabled; the shader will appear grayed out and disabled for the Lightworks and Virtualight render engines).

Skin looks more realistic when rendered using sub-surface scattering (image by Stan Slaughter)

Combined with Global Illumination, Sub-Surface Scattering is great for marble (statue from Stanford 3D Scanning Repository)

Notes and Tips: Do not use hierarchical objects – while photons can pass through the volume of one single  object, they will be blocked by any other objects (even if those objects are part of the same hierarchy, they are still considered separate objects in these calculations). This causes artifacts if the objects intersect. Use shadows, at least for they key lights in the scene if not for all lights. If you do not using  shadows, small objects may become illuminated via scattering even if they are in shadow. Even with Diffuse set to 0 in the Sub-surface Scattering shader, the surface can still be  illuminated due to the sub-surface scattering effect. Indeed, the higher the Diffuse value in the shader, the less visible the sub-surface scattering effects will be. Objects that use the Sub-surface Scattering shader can display soft shadows on their surface,  even if no soft shadows are enabled for V-Ray. This is because the light transmission through a surface painted with the Sub-surface Scattering shader will blur and soften the edges of the shadow. Note that this effect occurs from the Sub-surface Scattering calculations – if the shader includes Diffuse settings, these may “drown out” the sub-surface scattering effect so that the soft shadow is not seen, or not seen as clearly. Some sample images can be seen below:

Bottom plane uses Sub-surface Scattering shader with Diffuse = 0. Note the softened shadow due to light / shadow bleeding as light is scattered inside the material.

Bottom plane with Diffuse = 0.25. Note the appearance of a hard shadow edge from the regular lighting calculations for the Diffuse value in the shader.

Bottom plane now using Diffuse = 1. Hard edged shadows are now very prominent, although the Sub-Surface Scattering effects can still be seen.

5.4 Hair / Fur displacement Shader

While Workspace provides the full suite of hair modeling and rendering tools, you can obtain very quick results with this displacement shader, which is only found on the Model side. It allows efficient rendering as the individual hairs are efficiently generated only when needed (at rendering time – you won't see any indication of the fur in the Model). Unlike the full Workspace hair and fur, shadows are not supported and there are no styling tools. Despite these limitations, it's still a useful tool when you want to quickly apply fur all over an object.

The trueSpace dino gets a furry makeover

Density: number of individual hairs per unit area Length: length of individual hair Thickness: thickness of individual hair Softness: how soft the hair is, softer hair will bend due to gravity more To get better-looking results you usually want some variation in the hair strands. The following parameters allow you to add some randomness to the base values above: Dens. Var: variation in density of hair Length Var: variation in length Thick. Var: variation in thickness Soft. Var: variation in softness Dir. Var: when this is 0, every hair points directly out from the surface of the object. Add variation by increasing this value. Hair/Fur Shader panel

Segments: number of cylindrical segments for individual hair. You need to increase this for soft and long hair. Keep low for short hair to increase the rendering speed. Color: color of hair/fur

6. V-Ray Options and Parameters V-Ray options can be set from the V-Ray Options panel, which can be opened by right clicking on any of the rendering icons (similar to the render options toolbar for the Lightworks render engine) if V-Ray is the active render engine. This panel will open in the Tool aspect of the Stack view. Please note that this panel has four different aspects, which can be changed by clicking on the aspects button of the panel (which reads as “Default” initially – simply click and hold on this to see the list of available aspects, in the same was as aspects are changed for panels in the Link Editor). The Default aspect (pictured below) gives you basic controls over the main areas in the render engine, including some of the basic paramters for Global Illumination and Caustics. However, there is also a GI aspect which makes more detailed parameters for Global Illumination accessible, a Caustics aspect, which holds more detailed parameters for Caustics, and a Camera aspect, which contains settings for camera effects such as depth of field. The parameters in all four aspects of this panel are described below.

The V-Ray control panel in Default aspect

The V-Ray panel in GI aspect

6.1 View You can enter specific dimensions for the Workspace V-Ray Render View here. 6.2 Lights V-Ray supports Point lights, Spotlights, Distant lights, Projector lights and Area lights. For the parameters and controls of these light types, please see the relevant chapter in the trueSpace manual.

Note that Shadow Maps are not supported in V-Ray, so all lights will render with Raytraced shadows whether or not they have Shadow Map selected as their shadow type. The smooth shadow boundaries created by Shadow Maps are easily possible in V-Ray using alternative techniques – for example, you could use Area lights; you could use Global Illumination; or you could use the Soft Shadows option. The parameters that control lighting can be accessed in the Default aspect of the control panel. Transparent Shadows: Enables/disables computation of transparent shadows for transparent objects and object with transmission (e.g. glass). Note that in case of transmission the color of the shadow is defined by the color of the object, for transparent objects the shadows are gray.

Solid shadows, which do not look realistic for these particular objects

Transparent shadows enabled, which affects objects with refraction and those with transparency maps

Soft Shadows: Checkbox which enables soft shadow calculations in V-Ray renders. Soft shadows work with point or spot projector lights, and allow for a more realistic look to your renders, with shadows that grow softer the further they are from the shadow casting object.

A scene rendered with soft shadows

Soft shadows are generated by using a disc based approximation of point light sources. It is possible to control the size of the disc (and so control the sharpness of the shadow) as well as number of samples taken to compute it (which controls speed vs. quality). Size: Specifies the radius of the disc used to replace the point light for the shadow calculation. A small radius will mean sharper shadows. Note that in order to get a good quality approximation for a larger radius, you will need to increase the number of samples to avoid too much noise in the result. Samples: Controls the number of shadow samples taken during the evaluation of the shadow. A higher number means better quality and less noise, but a longer rendering time.

Hard shadows

Even low samples can give good results (here, Samples was set to 2)

Increasing Size gives softer shadows that spread further (here, Size = 4) – note this may need a higher Samples value for quality (Samples here = 8)

Soft Shadows also affect Transparent shadows when enabled; both objects with refraction and those with transparency maps are affected

Area lights will always give soft shadows no matter what setting you use in the options. They are a special type of light because instead of light rays coming from a single point, they model light as if it is coming from a plane. This can give much more realistic results. One thing to note is that falloff with area lights is treated slightly differently in V-Ray than with other types of lights; there are only two states, on or off. In practice, this means that setting the falloff in Model to “constant” means there is no falloff of brightness with distance, while setting it to linear or squared enables falloff.

Constant falloff

Squared falloff – note that linear falloff would give the same result

7. Global Illumination Global Illumination is the name given to a way of handling the light in a scene that will account not just for direct illumination (where a ray of light from a light source hits the surface of an object and is bounced to the eye), but also for other effects, such as light bouncing from one object onto another. This allows for very realistic renders, and is ideal for cases such as a room lit by a window (where light from the window bounces around the room to fill in shadows), color bleeding (where a blue wall will cast a blue light onto the white floor beneath it).

Real, or photograph? Thanks to Global Illumination, you could be fooled! (by Marcel Barthel)

As well as the effect of light sources that you place in the scene, Global Illumination also includes the effects of an “extra light source”, that being light from the surrounding environment. The color and intensity of this lighting is controlled by the Environment parameters (see below) and is ideal for rendering outdoor scenes where it will act as light from the sky, for example.

Global Illumination gives a similar kind of result as radiosity in other render engines supported by trueSpace (another mathematical model for calculating how light bounces around in a scene, not supported under V-Ray as Global Illumination replaces it), but Global Illumination under V-Ray is generally faster to render, and gives better quality results. Basic parameters for Global Illumination can be set in the Default aspect of the control panel, but below we will look at the detailed parameters which are available in the GI aspect of the control panel.

The V-Ray control panel in GI aspect, to reveal more advanced Global Illumination parameters

7.1 GI Parameters Enable: The checkbox to the left can be used to enable or disable Global Illumination computation. Note that GI is evaluated in multiple steps. The scene is sampled first (you see a scene rendering with sample points shown as they are calculated), and this sampling occurs over several steps (the scene will re-render at each step showing the smaller sample points used in each pass). The final image is computed as the last step.

Image without GI

Image with GI – note the color bleeding

Quality preset - this dropdown list allows you to choose from several presets for some of the GI parameters. The following presets are available: Very low: This preset is only useful for preview purposes to show the general lighting in the  scene. Low: A low-quality preset for preview purposes  Medium: A medium quality preset; works fine in many situations in scenes which have don't  small details. High: A high-quality preset that works in most situations, even for scenes with small details.  Very high: A very high quality preset; can be used for scenes with extremely small and  intricate details. Custom: This is used when the preset was modified by the user by manually changing one or  more of the parameters. Light in global illumination renders comes from two sources, primary and secondary. Primary light sources are light objects and environment lighting (sky, HDRI), while secondary light sources are light that is bounced from other surfaces in the scene. You can control the contribution of each type of source, as well as use different lighting engines for each, as V-Ray 1.5 added the ability to use light

maps, which are better able to handle secondary illumination without excessive rendering times. Further details on light maps can be found later. 1st Bounce: This is a multiplier which determines how much first diffuse lighting bounces contribute to the final illumination. Increasing this value makes the image brighter. 2nd Bounces: This is a multiplier which determines how much secondary light bounces contribute to the final illumination. Increasing the value increases the effect of secondary illumination and color bleeding in the image.

st

nd

1 Bounce=1, 2 Bounces = 1

st

nd

1 Bounce=1, 2 Bounces = 3

st

nd

1 Bounce=0.5, 2 Bounces = 3

7.3 Primary GI: Irradiance cache – used until now, good in most situations as it results in smooth illumination without artifacts. Light map – can be used to render light map without the need to complete Secondary: Direct – used until now, direct computation of secondary lighting (good for smooth lighting situations) Light map – better for scenes with more directionally-dependent illumination (interior scenes with windows) Environment: This sets the brightness and color to be used as an environment for Global Illumination. Double-click the color preview to open the color picker. For example, if you were rendering an outdoor scene on a sunny day, you would want to set a blue tint for this color, which would then act as light from the sky. Generally dark colors are all that is needed – the brightness of the color controls the brightness and strength of effect of the light from the environment, and too bright a color will result in washed out renders from too much illumination. Note that the color selected as the environment does not change the background color (as can be seen in the sample images below)

GI image with GI Environment = gray RGB(192,192,192)

GI image with GI Environment = yellow RGB(255,255,0)

Environment Image: This lets you use an image to act as the environment for Global Illumination. If an image is selected, then the Environment color selector has no effect. Note that this allows different color and intensity of lighting to come from different directions in the scene. Also note that this method of applying environment images only applies to Workspace; for Model side you should use the same HDRI Light method as with the Lightworks renderer. To select an image, double click on the “blank image” to the right of the parameter name, and this will let you select an image from the Workspace bitmap library. Alternatively, hold CTRL and double click in order to open a Windows file selection dialog to choose your image. It is suggested that you use .HDR files for your environments. To remove an Environment Image and return to using the plain Environment color, right click on the parameter title (where it says Environment Image, rather than on the image preview) and select Reset. Format: There are several common formats for HDR environment maps, and you should make sure you set this to match your image, as “Auto-Detect” can not always give the correct results Intensity: This controls the brightness of the global lighting generated from the image. If this is 0, no global illumination will be calculated.

Rfl Intensity: This separate control allows you to brighten or darken any reflections generated from the image. It also controls the brightness of the environment visible in the background – set this to 0 if you wish to disable environmental reflections Samples: A higher value will result in more accurate lighting at the expense of render time. If you set this to 0, no global illumination will be calculated Saturation: Allows you to modify how saturated the image is, from -1 to 1, with 0 being normal saturation and 0 being completely desaturated (grayscale) Show bkground.: When enabled, the environment image will be visible in the background of the scene whenever there is no geometry Env. Lighting only: When you are calculating lighting from the environment image, you usually want any actual lights in your scene to be disabled. This parameter controls that behavior. When environment lighting is enabled (Intensity and Samples both greater than 0), Vray will automatically do a global illumination pass, regardless of whether you have GI enabled or not. If you do not have it enabled, Vray will use GI settings optimized for HDRI lighting, so if you need a more complete GI solution, make sure you enable the regular GI checkbox. HemiSamples: A quality control for Global Illumination, this sets the number of hemispherical samples used during the irradiance computation. A lower number means fewer samples, which gives faster render times, but with a lower quality result. A higher number means more samples, which gives better quality, but longer rendering times. If the number of samples is too low, artifacts will appear as areas with high variance in their lighting, that is you will see lighter or darker spots on areas that should have smooth, constant lighting.

HemiSamples of 8, which renders quickly but leaves the HemiSamples raised to 15, which gives a much smoother result a little noisy result

InterpSamples: This is the number of GI samples that will be used to interpolate the indirect illumination at a given point. Larger values tend to blur the detail in GI although the result will be smoother. Smaller values produce results with more detail, but may produce blotchiness if not enough HemiSamples are used. You can use this to reduce render times by lowering the HemiSamples and raising the InterpSamples if sharp and precise detail in the GI effects are not required.

HemiSamples of 8 and InterpSamples of 10, which renders quickly but shows noise

Using InterpSamples of 20 blurs the result to reduce noise without the render time increase from raising the HemiSamples

QMC Samples: This determines the number of samples used to approximate GI. Note that this is not the exact number of rays that V-Ray will trace. The number of rays is proportional to the square of this number, but it can be reduced during the computation by adaptive sampling (further samples are not computed if the results are very similar). QMC Depth: This parameter controls the number of light bounces that will be computed for GI. A value of 0 results in just direct lighting being calculated, and no GI effects will be shown in the image. A value of 1 will add in the effect of the environmental lighting (set by the Environment color or image), but there will be no bounces calculated so effects such as color bleeding will not be shown. A value of 2 will add in one bounce of the diffuse lighting, and this will cause color bleeding to show up in the final render. A value of 3 will add in secondary bounces, enhancing color bleeding effects. Higher values will add in more bounces, but the effect of each bounce will be significantly less, and values above 3 may cause longer render times for insignificant changes in the final rendered image.

QMC Depth of 0 results in just direct lighting – that is, no Global Illumination effects at all

A QMC Depth of 1 calculates direct lighting, plus lighting from the environment (sky dome). No bounces are calculated, so there is no color bleeding

QMC Depth of 2 adds in a single bounce of lighting, and color bleeding now appears

A QMC Depth of 3 adds in secondary bounces in the lighting, enhancing color bleeding. Higher values are unlikely to make a significant change to the image

Threshold Parameters: The following three parameters (Color, Normal and Distance Threshold) control render time rather than affecting visual quality. The sampling process is adaptive, and if the samples are similar enough (that is, if the difference in color, normal and distance is small enough) then no further samples are taken even though a higher number of samples was specified by the user in these parameters. Color Threshold: This parameter controls how sensitive the irradiance map algorithm is to changes in indirect lighting. Larger values mean less sensitivity; smaller values make the irradiance map more sensitive to light changes (thus producing higher quality images). Normal Threshold: This parameter controls how sensitive the irradiance map is to changes in surface normals and small surface details. Larger values mean less sensitivity; smaller values make the irradiance map more sensitive to surface curvature and small details. Distance Threshold: This parameter controls how sensitive the irradiance map is to distance between surfaces. A value of 0.0 means the irradiance map will not depend on object proximity at all; higher values place more samples in places where objects are close to each other. Min Rate: This value determines the resolution for the first GI pass. A value of 0 means the resolution will be the same as the resolution of the final rendered image, which will make the irradiance map similar to the direct computation method. A value of -1 means the resolution will be half that of the final image, -2 means it will be one quarter of the resolution, -3 means it will be one eighth of the resolution, and so on.

You would usually want to keep this negative, so that GI is quickly computed for large and flat regions in the image. Max Rate: this value determines the resolution of the last GI pass. Note that the actual number of Irradiance map (GI) pre-passes is determined by a difference between Max Rate and Min Rate values. Using a lower Min value will allow the renderer to quickly decide on areas that do not require extra detail in their computation, reducing render time and increasing detail by focusing processing time only on those areas that need it most – this gives an advantage to setting a lower Min Rate (rather than setting both Min and Max Rate to the same value) as it can cut down on unnecessary computation. Max Rate follows the same rules as Min Rate, in that 0 is the same resolution as the image, -1 is half the resolution, and so on. You may want to set a value of greater than 0 for Max Rate, for example using a value of 1 will give a final resolution of twice the rendered image. Calculating the GI effects at a higher resolution than the rendered image gives a smoother and higher quality result, but at the expense of greater render time.

Min and Max Rate set to -6; note the lack of detail in the color bleeding

Min and Max Rate set to -3; now color bleeding can be seen from each cube

Min and Max Rate set to 0; significantly increased render time, but shows even finer detail in the color bleeding

Light map samples: number of samples to take for GI Light map (more samples means more detail but longer rendering time) Sample size: determines the spacing of the samples in the light cache. Smaller numbers mean that the samples will be closer to each other, the light cache will preserve sharp details in lighting, but it will be more noisy and will take more memory. Larger numbers will smooth out the light cache but will lose detail. Store direct light: determines whether the light cache will also store and interpolate direct light. This can be useful for scenes with many lights using the irradiance map since direct lighting will be computed from the light cache, instead of sampling each and every light. Note that only the diffuse illumination produced by the scene lights will be stored. If you want to use the light cache directly for approximating the GI while keeping the direct lighting sharp, uncheck this option. Prefilter Light map: the samples in the light cache can be filtered before rendering. Note that this is different from the normal light cache filtering which happens during rendering. Prefiltering is performed by examining each sample in turn, and modifying it so that it represents the average of the given number of nearby samples. 7.2 GI Notes and Tips:  The main parameters for controlling quality of shadows and color bleeding are the HemiSamples and the Max Rate parameters. A higher Max Rate will give higher resolution



calculations for each area, while the HemiSamples will give greater accuracy in those calculations. Raising either or both of these values will result in less noise in the final image. QMC Samples can also result in less noise, though the effect is much less pronounced than with changes to the HemiSamples and Max Rate parameters. QMC Depth does not affect the amount of noise, but controls the number of “bounces” computed for the GI effects (values above 3 are unlikely to contribute significantly to the image).

In order to reduce the amount of noise (and the rendering time) the direct computation of secondary illumination is typically restricted to a few light bounces only (3 being a default). However this means that significant portion of the lighting is not accounted for. This is typically compensated for artificially by increasing the 1st bounce/2nd bounces coefficient to increase the GI effect. Increasing the depth means longer rendering times but better lighting. The best results are typically achieved using the irradiance cache for primary GI engine and light map for secondary engine – this is true especially for scenes with a lot of secondary lighting. Also, if you combine irradiance cache with light map it is typically good enough to keep irradiance cache parameters at the “Low” preset. Below you can see several examples of light maps at work and see for yourself how they improve quality without having to increase the QMC depth.

Light map computation in early stages

Final Light map Note that you already have pretty good information on scene lighting

Final rendered image Irradiance cache + Light Map

Light Map + Light Map

Irradiance + Light Map

The Light map can be set as the primary engine for GI as well. However it is quite tricky to control the parameters to achieve acceptable results.

Irradiance + Direct – QMC depth = 3

Irradiance + Direct – QMC depth = 6

Irradiance + Direct – QMC depth = 15

Irradiance + Light Map

8. Caustics Caustics are the highlights caused by specular energy transfer, for example when light is focused through a glass object, or reflected off a mirrored surface.

The V-Ray control panel in Caustics aspect

8.1 Caustics Settings Enable: Use the checkbox at the left to enable or disable the computation of caustics. Calculating caustics involves the use of photon maps, which are computed before the actual rendering starts (so you may see a noticeable delay prior to rendering when caustics are selected). Caustics can add greatly to rendering times, especially if using a high number of photons.

Metal ring without caustics

Metal ring with caustics

Factor: This factor controls the strength of the caustics. It is global and applies equally to all light sources that generate caustics. Use it to control the visibility of the caustics effect. Typically you can leave this at value 1, though sometimes the value needs to be increased significantly, for example to

100 or 1000. Often setting this value high first can help in finding the correct values for the caustics parameters. Photons: The number of photons to trace for every light source in order to generate a photon map. A higher number means better quality, but longer render times. Distance: When V-Ray traces a photon that hits an object, the raytracer searches for other photons on the same plane in the surrounding area (the search area). The search area is in fact is a circle with the original photon at its center, and the Distance parameter controls the radius of that circle. Typically the value should cover the distance of few image pixels as converted to the 3D model space. Too low a value may result in separate areas of light and dark (due to the search area circles being too small to overlap). Too large a value may result in unnecessarily long render times.

Caustics with Distance = 0.003, the small value for means the individual photons traced are visible and do not merge, giving a speckled appearance

Caustics with Distance = 0.007, the larger size of area sampled for each photon allows a smooth result.

Notes and Tips:  Small Distance settings can lead to sharp caustic effects, but you may require higher numbers of photons (and so longer render times) to avoid a speckled appearance in the result, as the search area may be too small for the effects from individual photons to overlap. Raising the Distance parameter will also help remove the speckled look, but at the expense of the caustics looking softer or more blurry.  Use shadows, at least for they key lights in the scene if not for all lights. If you do not using shadows, small objects may become illuminated via scattering even if they are in shadow.

9. Save and Load Irradiance, Light, and Photon maps It is possible to save and load Irradiance, Light, and Photon maps, useful when doing multiple renderings with the same scene. These options let you calculate Global Illumination or Caustics and save the result, with Global Illumination being saved to an Irradiance map or Light map, and Caustics being saved to a Photon map. This allows the map or maps to be loaded later when rendering the same scene (for example, from a different perspective or viewpoint, or to a different image size), removing the need to repeat the Global Illumination or Caustic calculations and so speeding up the rendering process on those subsequent renders. Do note that Photon maps (for Caustics) are view independent, so once calculated and saved, you can render an image using that photon map from a different viewpoint. Irradiance maps (for Global Illumination) are view dependent however – the lighting is calculated for the objects visible in the image at the time of saving the Irradiance map. Rendering from a different viewpoint with an Irradiance map loaded may result in samples being missing in areas of the scene which were not visible from the previous viewpoint when the Irradiance map was calculated and saved. Saving an Irradiance map remains useful for rendering to different image sizes without the need to recalculate, so that you can render smaller test images, and then a final large image without the need to recalculate the GI effects. 9.1 Map Settings Save Map: Checkboxes that control whether the irradiance, light, and photon maps are saved to file after rendering Load Map: Load the irradiance, light, or photon map from file prior to the rendering (skips the map generation by the render engine). Open file: Opens the file dialog to select the file name File path edit: An edit field that allows the user to type the file name/path into the dialog. 9.2 GI Maps Notes and Tips: Below is a sample of the intended workflow for saving and using Irradiance maps (the same workflow steps would also apply for Photon and Light maps): Check Save Irrad. Map  Specify the name of the file to save the map to by either typing the file path to the dialog  entry, or clicking on the button left of the file path entry to open the file dialog and pick a file.



 



Render the scene as normal – the map is saved to the file at this point. You do not need to render the scene to file to save the map, rendering to screen will work equally well Render portion of the scene is also possible but note that in this case only a portion of the map is evaluated – the other parts might than be missing in sub-sequent renderings. Uncheck Save Irrad. Map Check Load Irrad. Map - note that in following this workflow, you have the path to file specified already. If you have loaded a scene later in another session, then you may need to specify the name of the file to load. Render again, for example from a different viewpoint. Since the map is pre-computed, the rendering is considerably faster.

Note that if you change any geometry, lighting or materials then the maps will no longer be valid. Using a saved map in a scene that is different in any way from the scene the map was made from will give unpredictable results. Also note that you need to enable Global Illumination if you want to load an Irradiance or Light map, and enable Caustics if you to load a Photon map. Checking an option to load a map will have no effect without the associated Global Illumination or Caustics checkboxes also being selected.

10. Depth of Field “Depth of field” is a term used to describe a visual effect where the area you are looking at is in sharp focus but the areas in front and behind are blurred. It is a great way to bring your scenes to life, literally adding depth and perceptual cues and heightening photorealism.

The DOF controls are included in the Camera aspect of the V-Ray options panel

10.1 DOF Settings Aperture: this is the size of the virtual camera aperture, in world units. Small aperture sizes reduce the

DOF effect, larger sizes produce more blur. Apertures of 0.2 and 2.0

Subdivisions: controls the quality of the DOF effect. Lower values are computed faster, but produce more noise in the image. Higher values smooth out the noise, but take more time to render. With very large aperture settings, you will definitely need to increase the subdivisions to avoid excessive noise.

Subdivisions of 1 and 10

Distance: determines the distance from the camera at which objects will be in perfect focus. Objects closer or farther than that distance will be blurred.

Distances of 7.0, 15.0, and 25.0

Sides: When enabled, Vray simulates the polygonal shape of a real-world aperture with the number of sides you specify. Otherwise, Vray assumes a perfectly circular aperture. Rotation: specifies the orientation of the aperture shape. Anisotropy: allows the stretching of the DOF effect horizontally or vertically. Positive values stretch the effect in the vertical direction. Negative values stretch it in the horizontal direction. Center bias: this determines the uniformity of the DOF effect. A value of 0.0 means that light passes uniformly through the aperture. Positive values mean that light is concentrated towards the rim of the aperture, while negative values concentrate light at the center.

11. Rendering Options Additional rendering options which will affect all the render engines can be set from Render Options Toolbar (Model only) or the PhotoRender Options Panel. This panel, and a description of how each of the parameters affects V-Ray in particular, can be found below.

The PhotoRender control panel

11.1 General Rendering Settings Rendering Quality: Wireframe: Not supported under V-Ray.  Hidden Line: Not supported under V-Ray  Medium: This renders with textures taken directly from the Workspace, which gives fast  rendering with medium quality. Note that the Workspace textures can be down-sampled resulting in loss of details on textured surfaces. High: This renders with full size textures and gives the best possible quality, although there is  potentially longer start-up and rendering times as a result of the larger memory requirements from the larger textures. Note that there is no difference between Medium or High settings in scenes which have use no textures. Render Method: This has no effect on rendering with V-Ray. It is suggested that this is left set to RayCast to ensure equivalent results should you switch to another render engine. Anti-Aliasing:

• • • • • •

Draft: Very fast rendering with the width and height of the image reduced in half. Suitable for fast previews. None: No anti-aliasing. Fast, but jagged edges will appear in the image. 2X: Super-sampling with 2x2 kernel. Every pixel is computed as an average of 4 sample points. 3X: Super-sampling with 3x3 kernel. Every pixel is computed as an average of 9 sample points. 4X: Super-sampling with 2x2 kernel. Every pixel is computed as an average of 16 sample points. Adaptive: Very high quality analytical anti-aliasing for superior image quality.

Adaptive is the suggested optimal anti-aliasing setting. Note that adding anti-aliasing will result in longer render times, with 4X anti-aliasing being slowest of all. Adaptive should give better results that 2x anti-aliasing, and with faster render times. 3X and 4X anti-aliasing may give better results than Adaptive (although Adaptive can often match those in quality), but with longer render times. Triangulate: This has no effect on rendering with V-Ray. Multithread: Enable or disable support for multiple processors or processors with HyperThreading technology. SingleSide: Enable or disable support for single-sided rendering. When single sided rendering is selected (the box is checked) then normals are not corrected to face the illumination direction, which results in slightly faster rendering but may reveal artifacts caused by back-facing surfaces. Doublesided rendering (when the box is unchecked) adjusts the normals to be always facing the illumination direction, which removes the chance of artefacts in the render, but at the expense of a slightly longer render time. Raytracing Options:   



Enabled: Turn or off reflection and refraction in the scene. Max Depth: The level of recursion for tracing rays. A higher value will result in slower but more accurate rendering of reflective and (especially) refractive surfaces. Min. Contrib: This parameter is for limiting the amount of reflections in the scene and is directly related to the “reflection” value of a material. When that value is lower than the Min. Contrib. setting, no reflections will be calculated for that object Limit: This value controls how much a ray has to contribute to the scene to be included in the final rendering calculations. Increasing this value can reduce rendering time at the expense of accuracy.

Render Engine: This provides the same function as Model's Preferences option and is included as a convenience. 11.2 Background The background settings are found in their own aspect, as shown below:

   

Color: A single color is used as the background. The color itself can be set by right clicking on the icon in the Rendering Options Toolbar. Image: An image is used as the background (stretched to fit the screen). The image to use as the background can be set by right clicking on the icon under the Rendering Options Toolbar. Clouds: This is not supported under V-Ray. Only the Background color from the Clouds settings would be used, so the Color background option should be used instead. Graduated: This is not supported under V-Ray. Only the Top color from the Graduated settings would be used, so the Color background option should be used instead.

12. HDRI HDRI is now supported under V-Ray as well as under Lightworks. The various HDRI settings are found under the Environment parameters in the Global Illumination options and are explained in that section, but for backwards compatibility the Model-side interface (the same one as for Lightworks HDRI) is still available. When using this legacy interface, most of the settings for V-Ray work in the same way as the settings for HDRI under Lightworks, so please see the chapter “HDRI” for details. Differences from HDRI under Lightworks are noted below.

HDRI makes this abstract object look real, thanks to the shadows and reflections(by Mike Harris)

12.1 HDRI Settings Shadow Computation: HDRI lighting is evaluated using Irradiance maps in case of V-Ray (similar to V-Ray GI). Thus the quality of shadows cast by HDRI light map is much better than in case of Lightworks. On the other hand, in case of V-Ray it is not possible to compute HDRI lighting without shadows (this is an inherited limitation of irradiance maps). Background Smoothing and Angle parameter: When the HDRI environment image is displayed as a background, V-Ray smooths the image to remove pixellation and color banding, giving a better quality result for the background. Because of this, the Angle parameter is not required (as it is intended to introduce blurring to avoid the pixellation and color banding) and has no effect on HDRI when rendering using V-Ray. Mapped Shadows: V-Ray does not support mapped shadows, so selecting this under the HDRI Shadow options will have no effect.

Samples and other parameters: Although the other parameters are functionally the same way as HDRI under Lightworks, you may need to change the values under V-Ray in order to achieve similar results for example, you may need to raise or lower the Samples attribute in order to find an equivalent balance between speed and quality. Some examples are given below on how the various HDRI parameters affect the result from V-Ray. 12.2 HDRI Examples

Samples = 7

Samples = 20 (note smoother shadowing)

Saturation = 0.5 (colors from lighting are more muted)

Saturation = 0 (no color at all from lighting, only surface colors remain)

Light Intensity = 1

Light Intensity = 2.5

12.3 HDRI Notes and Tips Global Illumination Settings Since HDRI calculations use Irradiance maps, some of the settings under the GI aspect will change how HDRI is calculated (even when the GI Checkbox is left unchecked and GI is not selected). HemiSamples: Has no effect on HDRI lighting, is replaced by the HDRI Samples parameter. InterSamples: Will affect HDRI in the same way as it affects GI, please see the section on Global Illumination for more information. QMC Samples and Depth: Will have no effect on HDRI lighting, as these relate only to bounced light in the scene. No bounced light is calculated for HDRI on its own. Min and Max Rate: Will affect the pre-passes for HDRI in the same way as they affect GI, please see the section on Global Illumination for more information.

13. TUTORIALS Choosing How to Render in V-Ray V-Ray offers many different methods of rendering and many different options. If you are used to other render engines, it may take some time to “rethink” a scene in terms of how V-Ray renders, and it may be tricky to decide just what effects and options you want to use for a given scene. You could just turn on everything and hope for the best, since Global Illumination, Caustics, HDRI and soft shadows all improve the look of a scene, so why not just use them all each time? To help you make an informed decision, here is a quick guide to approaching rendering in V-Ray! There is of course no right and wrong in the answer, and what follows is to help guide you in your choice. The biggest decisions facing you will be relating to the quality of the end result, against the time taken to render it, as even a fast engine such as V-Ray will need time to calculate Global Illumination and Soft Shadows and Caustics combined!

13.1 Quick and Simple

Regular V-Ray render (2 spotlights, 1 infinite light) A good way to start is to render the scene quick and simple! Just because there are options for HDRI, Global Illumination, Caustics and more does not mean you have to use them. Certainly for initial rendering while modeling or setting up a scene, leaving the more advanced options

deselected will help speed your workflow – and may well be enough for a simple render for an illustration or diagram, for example. 13.2 Soft Shadows

With Soft Shadows enabled

Perhaps one of the quickest and easiest changes you can make for rendering your scene is to add soft shadows. Depending on how many lights you have used in your scene, these should not take long to calculate, and yet can add a “less computer generated” look thanks to the softer shadows. Since the shadows appear “hard edged” when close to a shadow casting object, and grow softer with distance, this can add a dramatic amount of realism and interest with comparatively little overhead in render time. 13.3 HDRI for Reflection Only

HDRI reflection only (no lighting; but with Soft Shadows)

HDRI has two main benefits – one is the realistic reflections and refractions for glass and metal objects, and the other is the lighting and shadowing. However, you can take advantage of the reflections without the overhead of calculating the lighting– for example, if you are satisfied with your lighting using soft shadows alone, but you want to take advantage of the benefits of the reflections and refractions in your scene, to get a result like shown above. Note that since HDRI uses irradiance maps, the same as Global Illumination, then V-Ray needs to do multiple passes in order to calculate the lighting from HDRI (which means there can be a benefit to using Soft Shadows only with regular lighting in the scene). To get the effect of the HDRI reflections only, simply set the HDRI Light Intensity to 0, but leave a value for Back Intensity. This will indicate that no lighting calculations should be done for HDRI lighting, but the effects of the reflections will still be calculated.

13.4 Full HDRI

HDRI (lighting and reflections)

If you want a render that looks very realistic or one where an object blends into a background environment or scene, then HDRI can be an extremely good solution. This is particularly useful for scenes with objects in isolation. For example, if you have an entire closed room with most of the items of furniture fully modeled, then HDRI is not a good solution – while it is true that light from the HDRI scene will come in through the window, there will be very little benefit from HDRI, since all the objects will already have something to reflect and refract from the modeled room, and the majority of the lighting will not be “environmental” lighting from a surrounding scene, but instead will be lighting bouncing from one object to the other – Global Illumination would be a more satisfactory solution in that case. However, if you have a close up of a cup on a kitchen table, without the rest of the room being modeled, then HDRI with an environment of a kitchen would be an ideal solution. Similarly, if you are modeling a car on a street, then an HDRI environment of outdoors will provide realistic lighting and reflection (most likely you will also want to model the pavement and sidewalk for the car to “stand” on, just as you modeled the kitchen table for the cup). Even a collection of quite a few objects which are outside will render well with HDRI, as they will reflect each other where necessary, and reflect the background environment from the HDRI when there is nothing in the scene to reflect, plus the lighting will give them a realistic and consistent look – so modeling a playground, or a house, or a street, could all be good examples of when HDRI will be a good solution.

The trade off for the quality and realism is that the render times may increase significantlyhowever, when realism and quality is paramount, HDRI can be a very good solution indeed. 13.5 Caustics

Caustics (also with Soft Shadows)

Caustics – the reflection or refraction of light from mirrored or glass objects - add significantly to render times, as they are quite complex to calculate. It is also surprising how infrequently they will add much to a scene, so be sure to give a lot of thought before enabling caustics in your render. If you look around you in the real world, it is surprising how little caustic effects occur in most situations, and if they do occur they are often so slight or unimportant as to not be missed if they were not there. Perhaps review your photograph albums, take a look at when caustics really were vital to the picture and when they were incidental, or simply not present. Indeed, sometimes their presence can act as a distraction or interference with the main focus of an image. Just because you have a dining table with glasses and shiny cutlery laid out on it does mean you must enable caustics. The car you render in the brightly sunlight street may well cast a caustic reflection from the chrome hubcaps onto the nearby pavement. However, the scene may well look natural and suit your purpose entirely without them, and it may not occur to the viewer that there is anything missing.

Of course, there are times when caustics are the whole reason for a render, and then they become worth the extra render time. They can at times make or break particular images. If you have the same dining table as above, but are focused in entirely on one glass of wine, then the caustic effects of light shining off that glass and passing through the glass and the wine may be critical to the image looking realistic. Or a close up of your chrome hub cap on the car may too look incomplete without the caustic effects – or simply look a hundred times more dramatic if they are included even if it looks fine without them! Other scenes may be greatly changed by the inclusion of caustics - a close up of a diamond or gem may benefit from the reflected sparkle on the surface on which it rests; a view of a dresser covered in perfume bottles, and with a large mirror at the back, may also benefit from the interplay of reflected and refracted light; or perhaps a chandelier or disco ball, where you want realistically calculated effects rather than simulated ones using project lights and similar. The point here is to consider whether caustic effects really are what your render is about. If they are not the focus of attention, or vital to the focus of attention, then consider leaving them disabled, otherwise you may add significant amount of times to your renders for fairly insignificant changes in the end result - just because you have a tool available does not mean you always have to use it!

Combining the previous approaches, with HDRI (reflections only), Soft Shadows, and Caustics

13.6 Global Illumination

Global Illumination, showing how light and color bounce off the car onto the ground

Global Illumination is best used when you want very realistic scenes, in particular where light is required to “bounce” from one object to another. This is ideal for any render that requires realism, particularly for indoor renders showing rooms and architecture, since frequently an entire room is lit by a single light source (be that a window, or a lamp) and most of the room is lit not from the direct light, but from the way the light bounces from walls and furniture. GI can be quite intensive to render, though with good settings it need not increase render times too much, depending on just how much fine detail is required in the Global Illumination effects.

13.7 Combining Global Illumination and Caustics

Global Illumination plus Caustics (the Global Illumination was saved as an Irradiance Ma prior to rendering with Caustics)

Combining both Global Illumination and Caustics can be effective, and the best way to do this is to take advantage of the ability to save Irradiance and Photon Maps. Work with just GI or just Caustics, adjusting the settings until you have the effect you want. Then simply render to save the Irradiance map (if you have been setting the GI first) or the Photon map (if you have been setting the Caustics first). After that you can then adjust the settings for the other effect while simply loading the map for the other effect, saving on render time.

13.8 Combining Caustics and HDRI

Caustics (saved as a Photon Map) and HDRI used for reflection only for a dramatic result

Another combination that can be effective is using HDRI and Caustics. Here the best method is to save the Caustics calculations to a Photon map, which can then be loaded while you adjust the HDRI settings. You can use the HDRI as a reflection environment only, as done previously, or you can use the effect of the HDRI lighting also.

Here HDRI Lighting and reflection is used, in combination with a saved Photon map for Caustics

As you can see from the above examples, you can achieve a vast range of different effects depending on how you choose to render using V-Ray. The almost-limitless choice can seem very confusing, so always keep in mind what it is you want your image to achieve – think of the look and the result, and what is important about your render, rather than thinking about the technology itself and what you can enable just because it is there! The above examples will guide you in making a decision as to what sort of look will best suit your purpose, so that you can get the results you desire while keeping your render times as short as possible by avoiding unnecessary effects. Working with Materials, by Manfred Moersner Materials are sometimes a bit of a mystery. They can appear very different depending on lights, on other materials that are reflected and of course also on the parameters set in V-Ray. One big difference is whether your are using global illumination (GI) or not. GI handles a lot of lighting automatically, while settting the lights manually until you are satisfied can be a lengthy job. Hopefully this manual has described the setting of parameters adequately, but what does it really look like? Here we have some experimenting to see the effects. This is only a very small insight but should prepare you for experimenting on your own whenever you get one of those ”standard“ materials that seem to look just as you wanted, but turn out quite different during rendering. Instead of being disappointed, think about the effects and then change to get the result you originally were looking for. First we've done a standard setup: 4 glass plates 9 spheres – one spot light that has its focus on the middle sphere

The glass plates have some reflecting effect, focusing the spotlight should show coloring between shadows and lights and the number of spheres shows different angles and reflections. So we will put first material on each sphere now and let VRay go, without GI.

This is supposed to be “Dull Metal”. Not that bad. OK, so how about if we switch on GI now ?

Wow, what a difference, from black to white, but why? That must be a mistake? Well, let's try the next metal we have, “Polished Metal”:

First try with GI off and only the spotlight lights the objects. OK, now what happens here when we switch on GI?

Same effect, mysterious? No, not really. If we inspect the scene we should notice that both GI renders are brighter than those only done with spotlight. Could it be that leaving only one light enabled (our spotlight) and then additionally enabling GI could have such an effect? Yes, this is indeed the case. Leaving any of our standard lights on while rendering GI has also another effect, rendering time can increase significantly. In our case one can notice this when rendering happens in the area of the spotlight with GI enabled. But as we will see, there is more that influences materials. Let us look at another effect we have, “Environment”, where we can set a surrounding picture for our scenery. This is of importance for reflective materials. So let us try the “Cool Chrome” material:

Hmmm, it reflects like chrome, but to be honest, it doesn't really look like it. OK, then let us get an environment bitmap, something covering the background to give a little bit of graphic noise that can be reflected. Searching around, it looks that hair from the trueSpace texture folder should do it. Let's use the bump version so that color won't influence the scene.

Wow, what a difference:

Almost like all of a sudden the curtain raises up, the flashlights start working. Yes, looks almost as if the Beatles returned on stage. But what do we actually have? The background simply is reflected and each sphere reflects the other spheres. In a real project it will of course be different. There we have all kind of objects mostly differently shaped and colored. So there it will look more natural. Environment bitmaps can have a significant influence on the appearance of materials as the following example shows, first without GI and bitmap:

What did we do here, well just used the flame texture from the trueSpace texture folder as the Environment bitmap. Now we have on one hand the “lightening up” when rendering GI with external light (our spotlight) and the environment shows those beautiful reflections. With one last picture we will end this section which was supposed to encourage everyone to inspect, think and to experiment. Reality never is what it looks like!

Sample V-Ray Materials The starter library of V-Ray materials contains a wide range of surfaces to get you started:

Let's render out our test scene using each of these materials. This time we still have the glass plate with the spheres on it, but around this scenery we build a box and add a sky light. Renderings were done without GI but we learned above already to be aware of differences. Examining the pictures should give some idea of how especially materials with reflections act different in their appearance. The light should now be reflected by the surrounding box while our spheres will reflect the box and the other spheres. Color of the box is a very light gray.

Notice that it seems those two spheres left in the middle row seem to have a tip showing towards us. It is just an optical effect, they really are still round spheres!

The last two materials are only there to show that the other ones really are glassy. A final example shows the first 9 materials with another setup. We have glass plates on the bottom, back, left, right and on the top of the box. Below bottom a light gray plate: