Tutorial Vray Interior

Tutorial: Study Hall Interior (lasted updated 03.01.2003)

[Download Scene] This is a brief tutorial for lighting an interior scene to be rendered with VRay 1.09n Advanced. It is not intended as a comprehensive tutorial on modeling, texturing or lighting of an architectural scene. The aim is to outline one particular workflow for setting up lighting with VRay, and should be viewed only as a guide for approaching similar interior scenes. Additive Lighting It is always helpful to approach the challenge of lighting a scene with a strategy in mind. In this scenario, we'll use an additive approach. This approach usually begins by starting in darkness and then progressively adding lights, one at a time. Lights are only added after the settings for the existing lights are satisfactory. This allows us to keep track of how each light contributes to the scene, before adding new ones. This also avoids having any unnecessary lights in the scene, that may cause unexpected results or increase render times. I generally start with Sky light, then add Sun light and finally, additional fill lights if required.

PREPARATION & SETUP 1. Start by hiding all the glass before calculating the Irradiance Map. Not only will this allow more light to pass through, it will also greatly speed up future test renders. 2. Set the render size to 400x300, and Image Sampler AA to Fixed: Subdiv=1. At this early stage, we want fast feedback, so the test renders can be small and jaggy. 3. Under Advanced Irradiance Map Parameters>Mode, make sure Bucket mode is checked. The render is divided into regions or "buckets" and each become visible when completed. A good size for buckets is 128x128 pixels. I also change the Render Region Sequence often while I'm working, so that I can see the area that I'm interested in first. For the initial test renders, I am mainly concerned with the light reaching the back wall, so I set the bucket sequence from Left>Right. 4. In the Render Dialogue Uncheck Global Switches>Reflections. Reflections add unnecessary samples to the IR map based on the color threshold setting. 5. Set Indirect Illumination (GI) to On. Use Irradiance Map Presets>Low. Make sure Show calc. phase is checked to see the IR map being calculated and where samples are taken.

SKYLIGHT/ENVIRONMENT LIGHTING 1. Create an Omni light and turn it Off. This overrides the default lights. Turn on Environment>GI Environment (Skylight). 2. Make sure Overide MAX's is checked. 3. Select a light blue colour, eg. R173 G208 B255 and set the Multiplier=4.0. The indirect lighting is a bit too dark. We have 2 options: i) increase the Skylight Multiplier or ii) use Color mapping option in the render dialogue. Color Mapping allows limited control of the contrast between bright areas and dark areas of the image. 4. In this case, we'll use Color mapping since the external areas have enough illumination and we only want to brighten the interior illumination. Set the Dark multiplier to 2.0. Tip: A handy trick is to reuse a Saved IR map while tweaking the color mapping multipliers. However,you can only save an IR Map calculated using Single mode and not Bucket mode. In future, VRay will have it's own Virtual Frame Buffer which will allow you to adjust Color Mapping values interactively. From the help file: The color mapping parameters "control how the color values are processed before they are written to the output buffer. Color correction can be very useful for indoor or poorly lit scenes - you can get a good image without increasing light and sky multipliers. Type - the type of color correction. Currently the only supported type is Linear multiply which will simply multiply the colors by a value based on their intensity. (A Logarithmic algorithm similar to Lightscape would be alot more useful) Dark mutliplier - the value that dark colors will be multiplied by. For indoor or poorly lit scenes, you may want to increase this value to get more light in dark areas. Light multiplier - the value that bright colors will be multiplied by. Normally you'd leave this to its default value of 1.0 which means that bright colors will not be altered.

SUNLIGHT 1. Create a Sun System. Sunlight Settings: Color: R255 G251 B237 Multiplier: 3.0 Shadow: On - VRay Shadows

2. Adjust the Sun system so that some direct light enters the interior spaces. Turn Off Indirect illumination (GI) calculation to reduce render times. GI is not necessary since we only want to see where direct sunlight penetrates into the interior space. The combination of Sunlight (Direct) and Skylight (Indirect) provides enough overall illumination for the interior. However, the render seems to have too much blue from the Skylight. The Skylight is dominant because of the low multiplier value for Secondary bounce. In order to increase the Indirect Illumination from the Sunlight, set the Secondary Bounce Multiplier=0.7 Note: This setting is different to adjusting color mapping multipliers. Color map settings affect the brightness of an image based on intensity before outputing to the VFB, whereas changing the GI multipliers affects the light contribution of each bounce during IR map calculation. Therefore, changing the bounce multipliers requires a recalculation of the IR map, whereas color mapping can reuse a saved IR map. Adjusting Color Bleed from Objects There are large areas of timber surfaces in this space which would make the space a bit warmer than what we have at the moment. In order to simulate this warm bounced light from the timber surfaces, we will increase the Generate GI Multiplier on all objects with the timber material. 1. Select all the objects in the scene with the Wood1 material. 2. In the Render Dialogue, click System>Object Settings... 3. The objects with the Wood1 material should already be highlighted in the Scene Objects list. Change the Generate GI to 1.5. The effect is very subtle but most noticeable on the ceiliings and walls. You can increase the multiplier on individual objects or objects with certain materials by repeating the previous procedure to tweak the amount of color bleed. For example, I also increased the Generate GI multiplier on the red painting on the wall.

FILL LIGHT Another thing to notice is that the Skylight and indirect illumination from the Sun has not cast shadows for small object, such as the handrail and balustrade. Increasing the IR map Min. & Max. rates may fix this, but will also significantly increase render time. Another option is to use an invisible VRaylight to simulate the light coming from the glazing. 1. Place a VRaylight at the glass wall. Make sure the Normal is pointing inwards, into the interior space. VRaylight Settings: Color: R255 G245 B217 Multiplier: 0.5 Invisible: Checked Type: Plane Notice the nice area shadow created by the VRaylight. The VRaylight should not be set to Store in IR map, because this tends to blur the area shadows when the IR map is sampled. 2. With all the lights and the IR Map on, this is a good time to tweak the Color Map settings again. The test renders should be fast since we are reusing the saved IR Map and only adjusting the Color Map multiplier values. For the final render, I used Bright=1.0 and Dark=1.8 FINAL RENDER SETUP 1. IR Map Calculation: Change the IR map preset to Medium or High. These presets are resolution-dependent and are optimized for 640x480 pixels. For the final render, the resolution will be 700x526 pixels, so the presets will be fine. 2. Change the Render Output Size to your desired resolution. Check the settings to make sure they are similar to the following image. 3. Make sure Don't delete, Auto save and Switch to Saved Map are checked. Leave the AA at Fixed rate=1. Then hit render to calculate the IR Map for the final resolution. After the IR map calculation, VRay will automatically switch to the saved map and reuse it. 4. Turn the VRaylight On. Increase the Subdivs to eliminate grain 5. Unhide the glass. Enable Reflections in the Global Switches Rollout. 6. Change the Image Sampler (AA) to Adaptive Subdivs=0,2. If the image has a lot of noisy effects, such as large areas with glossy reflections, simple two-level AA would be faster than Adaptive Subdivs.

POST PROCESSING Although VRay produces beautiful images, I generally always do a little post processing and fine tuning work in Photoshop. 1. Make a duplicate of the original layer. 2. Select Image>Adjustments>Color Balance. Choose Highlights and add more Red and Yellow to the duplicate layer. 3. Set the blending mode to Color, and reduce the Opacity of the duplicate layer to 30-50%. To add specular blooms: 4. Make another duplicate of the original layer. Screen this layer over the 2 existing layers. 5. Add a mask to this layer. Copy the image and paste it into the mask channel. This will mask out all the dark areas of the layer and only the bright areas will remain. Adjust the levels for the mask channel. 6. Add Gaussian Blur to soften the highlights and adjust the Opacity of this layer to your liking. Other effects such as Film Grain, DOF, blurs, etc. can also be added. CONCLUSION This scene proved an interesting challenge since it has both interior and exterior spaces. By using some of the features in VRay, we were able to achieve very natural and realistic lighting in a fairly short amount of time. When approaching a lighting challenge, it is helpful to have a plan of attack. One useful strategy is to light the scene "Additively" starting in darkness and adding lights one at a time. This allows us to adjust the numerous parameters and settings for each light in discrete stages. Skylight + Sunlight + Fill lights = Total Illimunation I hope you have found this tutorial useful and informative. We will add an exterior tutorial for this scene, again using VRay. And as new builds of VRay are released, we will try to update the tutorials so that they remain relevant. Please feel free to send feedback and suggestions to [email protected]. Have fun and...I love VRay, do you? Vu Nguyen|osmosis