Aoi
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Area Of Interest O N - L I N E
M A N U A L
Copyright 1982 - 1999 by ERDAS, Inc. All rights reserved. Printed in the United States of America. ERDAS Proprietary - Delivered under license agreement. Copying and disclosure prohibited without express written permission from ERDAS, Inc. ERDAS, Inc. 2801 Buford Highway, N.E. Atlanta, Georgia 30329-2137 USA Phone: 404/248-9000 Fax: 404/248-9400 User Support: 404/248-9777
Warning All information in this document, as well as the software to which it pertains, is proprietary material of ERDAS, Inc., and is subject to an ERDAS license and non-disclosure agreement. Neither the software nor the documentation may be reproduced in any manner without the prior written permission of ERDAS, Inc. Specifications are subject to change without notice.
Trademarks ERDAS is a trade name of ERDAS, Inc. ERDAS and ERDAS IMAGINE are registered trademarks of ERDAS, Inc. Model Maker, CellArray, ERDAS Field Guide, and ERDAS Tour Guides are trademarks of ERDAS, Inc. Other brands and product names are trademarks of their respective owners.
Area Of Interest On-Line Manual Create AOI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Create AOI from Raster Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Create AOI from Vector Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Create AOI from Annotation Layer . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Rules for Pixel Inclusion within Polygons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Choose AOI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Area of Interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 AOI Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 AOI Tools (Large Format) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 AOI Tools and Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 AOI Tools and Commands (Large Format) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 AOI Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 AOI Styles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Region Growing Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Region Grow Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Save AOI As ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
iii
Create AOI
Create AOI Follow these instructions to create an area of interest (AOI) from a raster layer, vector layer, or annotation layer. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. Create AOI from Raster Layer To create an AOI from a raster layer mask, the raster layer must be a pseudocolor layer and it must be in the same projection system as the AOI layer. You can create an AOI from a raster layer in the same Viewer or in a different Viewer. The instructions below assume that you are creating an AOI in Viewer #1 and will display the mask raster layer in Viewer #2. 1. Display the pseudocolor layer from which you want to create the AOI in Viewer #2. This layer must be in the same map projection as the image in Viewer #1. 2. From the menu bar of Viewer #2, select Raster | Attributes... The Raster Attribute Editor is opened. 3. In the Raster Attribute Editor or in Viewer #2, select the class(es) you want to use to create the AOI. 4. In the menu bar of Viewer #1, select AOI | Copy Selection to AOI... If an AOI layer already exists, then the new area is added to it. If an AOI layer does not already exist, then it is created and the new area is added to it. Some AOI objects, such as rotated ellipses or rectangles are incorrect if the pixel aspect ratio of the underlying raster image is not equal to 1 (i.e., non-square pixels). Create AOI from Vector Layer Creating an AOI from a vector layer works almost the same as creating an AOI from a raster layer. Again, we will assume that you are creating the AOI in Viewer #1 and will display the mask vector layer in Viewer #2. Follow the steps below. 1. Display the vector layer from which you want to create the AOI in Viewer #2. This layer must be in the same map projection as the image in Viewer #1. 2. In Viewer #2, select the feature(s) you want to use to create the AOI.
1
Create AOI 3. In the menu bar of Viewer #1, select AOI | Copy Selection to AOI... If an AOI layer already exists, then the new area is added to it. If an AOI layer does not already exist, then it is created and the new area is added to it. Create AOI from Annotation Layer Follow the steps for creating an AOI from a vector layer.
☞ Remember that you do not need to use two Viewers to perform the steps above.
2
Rules for Pixel Inclusion within Polygons
Rules for Pixel Inclusion within Polygons When rasterizing an AOI for subsetting an image, extracting a training signature, calculating image statistics etc., IMAGINE must determine whether to include partial pixels within the AOI. A partial pixel is one that is not fully contained within the selected region. This happens when one or more edges of the AOI polygon intersect a pixel. There are two rules that IMAGINE applies when determining if a pixel is included: 1. If the polygon boundary contains at least one mid-point of the pixel edge, the pixel is included in the region. 2. If a polygon boundary vertex lies within the pixel, the pixel is included in the region. Consider the following image and AOI polygon:
The figure below shows the pixels that ERDAS IMAGINE considers “inside” the AOI polygon for the purposes of statistics calculation, subsetting, etc. Pixel 1 (grey pixel at upper right) is included within the polygon because the mid-point of one edge falls within the polygon.
3
Rules for Pixel Inclusion within Polygons Pixel 2 (green pixel at right) is included within the polygon because a polygon vertex exists within the pixel extent.
1 2
Note that these rules are implemented in this manner to provide rapid selection of pixels. Unfortunately the rules are not mutually exclusive. Consequently, a single pixel can be considered to fall within more than one polygon boundary. You should also take into account that if resampling is involved, pixel locations may appear to “shift” due to the creation of a new image origin that is not an integer pixel offset from the original origin. For instance, if using an AOI to subset an image while also using the Inquire Box to clip the AOI extent, Nearest Neighbor resampling of pixels will occur.
4
Choose AOI
Choose AOI This dialog lets you select an area of interest (AOI) to which to apply a function, excluding the rest of the image. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. This dialog is opened from any place in IMAGINE where you are allowed to select an AOI for processing. For example, this dialog is opened when you:
♦ click on the AOI button in any Image Interpreter dialog ♦ click on the Use AOI button in the Statistics Generation Options dialog in Image Info ♦ click on Model | Area of Interest in the Model Maker menu ♦ click the Set Constraint AOI button in the Region Growing Properties dialog AOI Source: Click on the appropriate radio button to select the AOI source to use for this operation: None File
Do not use an AOI. Click to use an existing AOI file. Select the file in the file name part below.
Viewer
Click to use the AOI defined in the Viewer.
AOI File: Use this file name part to select an AOI file. You must select the File option above to enable this option. The default file extension is .aoi.
OK Click to use the selected option and close this dialog. Cancel Click to close this dialog. Help Click to see this On-Line Help document.
5
Area of Interest
Area of Interest This dialog allows you to perform an operation upon a specific area of an image that is displayed in a Viewer. This dialog is opened when you click the From Viewer... option in another dialog.
Options: You have the following options for selecting an area of interest: Use Entire File Click to use the entire file regardless of the area visible in the Viewer. This is the default setting. Use Viewed Area
Click to use the area visible in the Viewer.
Use Inquire Box Click to display a white cursor box on the image. You can move and resize this box to select the area of interest. The Inquire Box Coordinates dialog is opened.
OK Click to use the selected area of interest and close this dialog. Cancel Click to close this dialog. Help Click to open this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
6
AOI Tools
AOI Tools The AOI Tools enable you to select and create areas of interest (AOIs). These AOIs are often used as input to the Signature Editor prior to image classification. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. This tool palette is opened when you select Raster | Tools... from the Viewer menu bar or, if the AOI layer is the top layer in the Viewer, when you click the
icon in the Viewer tool bar.
To enter specific position and size parameters, you can press the space bar while drawing many AOI objects, which opens a dialog that allows you to enter precise coordinates and size information.
i
The Preference Editor allows you to select large or small tools. This dialog is opened if you have selected small tools.
Click to select, move, and resize AOI elements. Press the Shift key and use the pointer tool to select multiple elements.
Click to select all AOI elements that fall within the boundary of the rectangular marquee that you draw. To draw a perfect square, shift-left-hold when drawing.
Click to create a rectangular AOI. In the Viewer, drag diagonally from the upper left to the lower right corner to create the rectangular AOI. To draw a perfect square, shift-left-hold when drawing.
Click to create an elliptical AOI. In the Viewer, drag from the center to the lower right “corner” to create the desired ellipse. To draw a perfect circle, shift-left-hold when drawing.
Click to create a polygonal AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to close the polygon.
7
AOI Tools
Click to create a polyline AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to end the polyline.
Click to select a single pixel from which an AOI “grows” based on the parameters set in the Region Growing Properties dialog.
Click to create a point AOI.
Click to see this On-Line Help document.
Click to unlock the currently selected tool.
Click to lock the currently selected tool until another tool is selected.
Close Click to close this tool palette. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
8
AOI Tools (Large Format)
AOI Tools (Large Format) The AOI Tools enable you to select, create, and edit areas of interest (AOIs). These AOIs are often used as input to the Signature Editor prior to image classification. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. This tool palette is opened when you select Raster | Tools... from the Viewer menu bar or, if the AOI layer is the top layer in the Viewer, when you click the
icon in the Viewer tool bar.
To enter specific position and size parameters, you can press the space bar while drawing many AOI objects, which opens a dialog that allows you to enter precise coordinates and size information.
i
The Preference Editor allows you to select large or small tools. This dialog is opened if you have selected small tools and you have opted to combine tools and commands.
Click to select, move, and resize AOI elements. Press the Shift key and use the pointer tool to select multiple elements.
Click to select all AOI elements that fall within the boundary of the rectangular marquee that you draw. To draw a perfect square, shift-left-hold when drawing.
Click to create a rectangular AOI. In the Viewer, drag diagonally from the upper left to the lower right corner to create the rectangular AOI. To draw a perfect square, hold the shift key while dragging.
Click to create an elliptical AOI. In the Viewer, drag from the center to the lower right “corner” to create the desired ellipse. To draw a perfect circle, hold the shift key while dragging.
9
AOI Tools (Large Format)
Click to create a polygonal AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to close the polygon.
Click to create a polyline AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to end the polyline.
Click to select a single pixel from which an AOI “grows”, based on the parameters set in the Region Growing Properties dialog.
Click to create a point AOI.
Keep Tool Click to lock the current tool until another tool is selected. Close Click to close this tool palette. Help Click to see this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
10
AOI Tools and Commands
AOI Tools and Commands The AOI Tools enable you to select, create, and edit areas of interest (AOIs). These AOIs are often used as input to the Signature Editor prior to image classification. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. This tool palette is opened when you select AOI | Tools... from the Viewer menu bar or, if the AOI layer is the top layer in the Viewer, when you click the
icon in the Viewer tool bar.
To enter specific position and size parameters, you can press the space bar while drawing many AOI objects, which opens a dialog that allows you to enter precise coordinates and size information.
i
The Preference Editor allows you to select large or small tools. This dialog is opened if you have selected small tools and you have opted to combine tools and commands.
Click to select, move, and resize AOI elements. Press the Shift key and use the pointer tool to select multiple elements.
Click to select all AOI elements that fall within the boundary of the rectangular marquee that you draw. To draw a perfect square, shift-left-hold when drawing.
Click to create a rectangular AOI. In the Viewer, drag diagonally from the upper left to the lower right corner to create the rectangular AOI. To draw a perfect square, hold the shift key while dragging.
Click to create an elliptical AOI. In the Viewer, drag from the center to the lower right “corner” to create the desired ellipse. To draw a perfect circle, shift-left-hold when drawing.
Click to create a polygonal AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to close the polygon.
Click to create a polyline AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to end the polyline.
11
AOI Tools and Commands
Click to select a single pixel from which an AOI “grows” based on the parameters set in the Region Growing Properties dialog.
Click to create a point AOI.
Click to undo the last edit. Select multiple times to undo a series of edits (back to the last saved version of this AOI layer).
Click to delete the selected element(s). A copy is kept in a copy/paste buffer.
Click to reshape a selected polygon or polyline:
♦ left-hold to move a vertex of the polygon or polyline; ♦ middle-click to add a vertex to the polygon or polyline; ♦ shift-middle-click to add or remove a vertex from the polygon or polyline; ♦ left-hold on any side of a polygon to move it without rotating. To quit reshape mode, click outside the element or select another element.
Click to combine the selected elements into a group element.
Click to break a group element into single elements.
Click to delete all raster areas from the AOI layer. Raster areas are created by using the AOI | Copy Selection to AOI... option of the Viewer menu bar from a pseudo color image.
Click to invert a region grown area so that everything not in the region grow is selected as an AOI. This option is helpful for selecting island polygons.
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AOI Tools and Commands
Click to bring up the Properties dialog for the selected element:
♦ Ellipse ♦ Rectangle ♦ Polygon/Polyline ♦ Point ♦ Group Click open the AOI Styles dialog.
Click to open the Region Growing Properties dialog.
Click to add the selected Raster, Vector, or Annotation object to the top AOI layer in the current viewer.
Click to link the selected AOI(s) to the specified window.
Click to create a new digitizing tablet configuration. The Tablet Setup dialog is opened.
Click to use an existing tablet configuration. The Map Setup dialog is opened along with the Tablet Status dialog.
Click to unlock the currently selected tool.
Click to lock the currently selected tool until another tool is selected.
Close Click to dismiss the AOI tools. Click to see this On-Line Help document.
13
AOI Tools and Commands
➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
14
AOI Tools and Commands (Large Format)
AOI Tools and Commands (Large Format) The AOI Tools enable you to select, create, and edit areas of interest (AOIs). These AOIs are often used as input to the Signature Editor prior to image classification. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. This tool palette is opened when you select AOI | Tools... from the Viewer menu bar or, if the AOI layer is the top layer in the Viewer, when you click the
icon in the Viewer tool bar.
To enter specific position and size parameters, you can press the space bar while drawing many AOI objects, which opens a dialog that allows you to enter precise coordinates and size information.
i
The Preference Editor allows you to select large or small tools. This dialog is opened if you have selected small tools and you have opted to combine tools and commands.
Click to select, move, and resize AOI elements. Press the Shift key and use the pointer tool to select multiple elements.
Click to select all AOI elements that fall within the boundary of the rectangular marquee that you draw. To draw a perfect square, hold the Shift key when drawing.
Click to create a rectangular AOI. In the Viewer, drag diagonally from the upper left to the lower right corner to create the rectangular AOI. To draw a perfect square, hold the shift key while dragging.
Click to create an elliptical AOI. In the Viewer, drag from the center to the lower right “corner” to create the desired ellipse. To draw a perfect circle, hold the Shift key while dragging.
15
AOI Tools and Commands (Large Format)
Click to create a polygonal AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to close the polygon.
Click to create a polyline AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to end the polyline.
Click to select a single pixel from which an AOI “grows”, based on the parameters set in the Region Growing Properties dialog.
Click to create a point AOI.
Click to undo the last edit. Select multiple times to undo a series of edits (back to the last saved version of this AOI layer).
Click to delete the selected element(s). A copy is kept in a copy/paste buffer.
Click to reshape a selected polygon or polyline:
♦ hold to move a vertex of the polygon or polyline; ♦ middle-click to add a vertex to the polygon or polyline; ♦ shift-middle-click to add or remove a vertex from the polygon or polyline; ♦ hold on any side of a polygon to move it without rotating. To quit reshape mode, click outside the element or select another element.
16
AOI Tools and Commands (Large Format)
Click to combine the selected elements into a group element.
Click to break a group element into single elements.
Click to delete all raster areas from the AOI layer. Raster areas are created by using the AOI | Copy Selection to AOI... option of the Viewer menu bar from a pseudo color image.
Click to invert a region grown area so that everything not in the region grow is selected as an AOI. This option is helpful for selecting island polygons
Click to bring up the Properties dialog for the selected element:
♦ Ellipse ♦ Rectangle ♦ Polygon/Polyline ♦ Point ♦ Group
Click open the AOI Styles dialog.
Click to open the Region Growing Properties dialog.
17
AOI Tools and Commands (Large Format)
Click to add the selected Raster, Vector, or Annotation object to the top AOI layer in the current viewer.
Click to link the selected AOI(s) to the specified window.
Click to create a new digitizing tablet configuration. The Tablet Setup dialog is opened.
Click to use an existing tablet configuration. The Map Setup dialog is opened along with the Tablet Status dialog.
Click to unlock the currently selected tool.
Click to lock the currently selected tool until another tool is selected.
Close Click to dismiss the AOI tools. Click to see this On-Line Help document.
➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
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AOI Commands
AOI Commands These AOI (area of interest) commands enable you to control the placement and properties of AOI elements in the Viewer. This dialog cannot be reached using the IMAGINE user interface. It can only be accessed through EML application functions commands. These commands are also found in AOI menu on the Viewer, and in the AOI Tools and Commands palette.
☞ You can also display these commands as icons in the AOI tool palette. This option is set in the viewer category of the Preference Editor.
Cut Select to delete the selected element(s). A copy is kept in a copy/paste buffer. Delete Raster Select to delete all raster areas from the AOI layer. Raster areas are created by using the AOI | Copy Selection to AOI... option of the Viewer menu bar from a pseudo color image. Group Select to combine the selected elements into a group element. Ungroup Select to break a group element into single elements. Reshape Select to reshape a selected polygon or polyline: ♦ hold to move a vertex of the polygon or polyline; ♦ middle-click to add a vertex to the polygon or polyline; ♦ shift-middle-click to add or remove a vertex from the polygon or polyline; ♦ hold on any side of a polygon to move it without rotating. To quit reshape mode, click outside the element or select another element.
Invert Polygon Select to invert a region grown area so that everything not in the region grow is selected as an AOI. This option is helpful for selecting island polygons.
Undo Select to undo the last edit. Select multiple times to undo a series of edits (back to the last saved version of this AOI layer).
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AOI Commands
Properties... Select to bring up the Properties dialog for the selected element: ♦ Ellipse ♦ Rectangle ♦ Polygon/Polyline ♦ Point ♦ Group Close Click to close this dialog. Help Click to see this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
20
AOI Styles
AOI Styles This dialog enables you to set default styles for areas of interest (AOIs). It is opened when you select AOI | Styles... in the Viewer menu bar. It is also opened when you click the the AOI Tools palette.
icon on
Chaser: Foreground Width: Enter the width (in pixels) of the foreground of the chaser line that is opened around AOIs. A larger number will make the dashes in the chaser longer. A smaller number will make the dashes smaller. The chaser line is made up of two parts: the foreground line and the background line. These lines can have different widths and colors to achieve the desired look. When both the foreground and background widths are the same size, but different colors, the line is opened to blink and rotate like marquee lights Color: Click on this color patch to select the color for the foreground line of the chaser. Background Width: Enter the width (in pixels) of background chaser line. Color: Click on this color patch to select the color for the background line of the chaser. Interval: Enter the chaser time interval in milliseconds. The smaller the number, the faster the chaser will blink. Thickness: Enter the chaser line thickness.
Polygon: Fill: Click to fill the AOI objects with a solid color. Fill Color: Click on this color patch to select the color for polygon fill.
Apply Click to apply the AOI style. Close Click to close this dialog. Help Click to see this On-Line Help document.
21
AOI Styles
➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
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Region Growing Properties
Region Growing Properties This dialog enables you to set parameters that affect region growing AOI selection. It is opened when you select Seed Properties... from the AOI, Vector, or Annotation menus in the Viewer menu bar. It also opens when you click on the
icon in the Annotation Tools palette.
Neighborhood: This option determines which pixels will be considered contiguous to the seed pixel. Any neighbor pixel that meets all selection criteria is accepted and thus, itself, becomes a seed pixel.
If four neighbors are searched, then only those pixels above, below, to the left, and to the right of the seed pixel are considered contiguous.
If eight neighbors are searched then the diagonal pixels are also considered contiguous.
Geographic Constraints: This group allows you to enter constraints for the AOI. You can select only one option or use both options. Area: Click to constrain by region area in pixels. Enter the maximum size of the AOI and then click on the accompanying popup list to select units as either # pixels, hectares, acres, or sq. miles. Distance: Click to constrain the AOI by specifying a distance from the seed pixel. Enter the distance and then click on the accompanying popup list to select distance units as either pixels, meters, or feet.
Spectral Euclidean Distance: Enter the Euclidean spectral distance in digital number (DN) units on which to accept pixels. The pixels that are accepted will be within this spectral distance from the mean of the seed pixel.
Grow at Inquire Click to grow a new region using the current properties. Set Constraint AOI... Click to specify an bounding AOI for the region grow. Options... Click to set other region growing parameters. The Region Growing Options dialog is opened.
Redo Click to redo the last region with same seed coordinate.
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Region Growing Properties
Invert Click to invert the selection to select islands within the region grow area. Close Click to close this dialog and save the selected parameters. Help Click to see this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For step-by-step instructions on selecting AOIs for training samples, see the Classification section of the ERDAS IMAGINE Tour Guides manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
24
Region Grow Options
Region Grow Options This dialog enables you to set additional parameters that affect region growing. It is opened when you click Options... in the Region Growing Properties dialog.
Include Island Polygons Click to enable the grow region to include island polygons. Update Region Mean Click to update the region mean as the region grows. Buffer Region Boundary Click to buffer the boundary of the region. This option is useful when you are selecting AOIs for editing DEM data, so that you can avoid sudden changes in elevation. Close Click to close this dialog. Help Click to see this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For step-by-step instructions on selecting AOIs for training samples, see the Classification section of the ERDAS IMAGINE Tour Guides manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
25
Save AOI As ...
Save AOI As ... This dialog enables you to save an AOI layer to a file. It appears when you left-hold File | Save AOI Layer As... in the Viewer menu bar when an AOI layer is displayed in the Viewer, or whenever ERDAS IMAGINE allows you to save AOI layers.
Save AOI as: Use this file name part to enter the name of the AOI. The .aoi extension is added automatically.
Selected Only Click to save only the AOIs which are selected in the Viewer. If this option is not checked, then all AOIs will be saved. OK Click to save the AOI(s) and close this dialog. Cancel Click to close this dialog without saving the AOI(s). Help Click to see this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of the on-line AOI manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
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M A N U A L
Copyright 1982 - 1999 by ERDAS, Inc. All rights reserved. Printed in the United States of America. ERDAS Proprietary - Delivered under license agreement. Copying and disclosure prohibited without express written permission from ERDAS, Inc. ERDAS, Inc. 2801 Buford Highway, N.E. Atlanta, Georgia 30329-2137 USA Phone: 404/248-9000 Fax: 404/248-9400 User Support: 404/248-9777
Warning All information in this document, as well as the software to which it pertains, is proprietary material of ERDAS, Inc., and is subject to an ERDAS license and non-disclosure agreement. Neither the software nor the documentation may be reproduced in any manner without the prior written permission of ERDAS, Inc. Specifications are subject to change without notice.
Trademarks ERDAS is a trade name of ERDAS, Inc. ERDAS and ERDAS IMAGINE are registered trademarks of ERDAS, Inc. Model Maker, CellArray, ERDAS Field Guide, and ERDAS Tour Guides are trademarks of ERDAS, Inc. Other brands and product names are trademarks of their respective owners.
Area Of Interest On-Line Manual Create AOI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Create AOI from Raster Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Create AOI from Vector Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Create AOI from Annotation Layer . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Rules for Pixel Inclusion within Polygons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Choose AOI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Area of Interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 AOI Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 AOI Tools (Large Format) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 AOI Tools and Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 AOI Tools and Commands (Large Format) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 AOI Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 AOI Styles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Region Growing Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Region Grow Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Save AOI As ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
iii
Create AOI
Create AOI Follow these instructions to create an area of interest (AOI) from a raster layer, vector layer, or annotation layer. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. Create AOI from Raster Layer To create an AOI from a raster layer mask, the raster layer must be a pseudocolor layer and it must be in the same projection system as the AOI layer. You can create an AOI from a raster layer in the same Viewer or in a different Viewer. The instructions below assume that you are creating an AOI in Viewer #1 and will display the mask raster layer in Viewer #2. 1. Display the pseudocolor layer from which you want to create the AOI in Viewer #2. This layer must be in the same map projection as the image in Viewer #1. 2. From the menu bar of Viewer #2, select Raster | Attributes... The Raster Attribute Editor is opened. 3. In the Raster Attribute Editor or in Viewer #2, select the class(es) you want to use to create the AOI. 4. In the menu bar of Viewer #1, select AOI | Copy Selection to AOI... If an AOI layer already exists, then the new area is added to it. If an AOI layer does not already exist, then it is created and the new area is added to it. Some AOI objects, such as rotated ellipses or rectangles are incorrect if the pixel aspect ratio of the underlying raster image is not equal to 1 (i.e., non-square pixels). Create AOI from Vector Layer Creating an AOI from a vector layer works almost the same as creating an AOI from a raster layer. Again, we will assume that you are creating the AOI in Viewer #1 and will display the mask vector layer in Viewer #2. Follow the steps below. 1. Display the vector layer from which you want to create the AOI in Viewer #2. This layer must be in the same map projection as the image in Viewer #1. 2. In Viewer #2, select the feature(s) you want to use to create the AOI.
1
Create AOI 3. In the menu bar of Viewer #1, select AOI | Copy Selection to AOI... If an AOI layer already exists, then the new area is added to it. If an AOI layer does not already exist, then it is created and the new area is added to it. Create AOI from Annotation Layer Follow the steps for creating an AOI from a vector layer.
☞ Remember that you do not need to use two Viewers to perform the steps above.
2
Rules for Pixel Inclusion within Polygons
Rules for Pixel Inclusion within Polygons When rasterizing an AOI for subsetting an image, extracting a training signature, calculating image statistics etc., IMAGINE must determine whether to include partial pixels within the AOI. A partial pixel is one that is not fully contained within the selected region. This happens when one or more edges of the AOI polygon intersect a pixel. There are two rules that IMAGINE applies when determining if a pixel is included: 1. If the polygon boundary contains at least one mid-point of the pixel edge, the pixel is included in the region. 2. If a polygon boundary vertex lies within the pixel, the pixel is included in the region. Consider the following image and AOI polygon:
The figure below shows the pixels that ERDAS IMAGINE considers “inside” the AOI polygon for the purposes of statistics calculation, subsetting, etc. Pixel 1 (grey pixel at upper right) is included within the polygon because the mid-point of one edge falls within the polygon.
3
Rules for Pixel Inclusion within Polygons Pixel 2 (green pixel at right) is included within the polygon because a polygon vertex exists within the pixel extent.
1 2
Note that these rules are implemented in this manner to provide rapid selection of pixels. Unfortunately the rules are not mutually exclusive. Consequently, a single pixel can be considered to fall within more than one polygon boundary. You should also take into account that if resampling is involved, pixel locations may appear to “shift” due to the creation of a new image origin that is not an integer pixel offset from the original origin. For instance, if using an AOI to subset an image while also using the Inquire Box to clip the AOI extent, Nearest Neighbor resampling of pixels will occur.
4
Choose AOI
Choose AOI This dialog lets you select an area of interest (AOI) to which to apply a function, excluding the rest of the image. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. This dialog is opened from any place in IMAGINE where you are allowed to select an AOI for processing. For example, this dialog is opened when you:
♦ click on the AOI button in any Image Interpreter dialog ♦ click on the Use AOI button in the Statistics Generation Options dialog in Image Info ♦ click on Model | Area of Interest in the Model Maker menu ♦ click the Set Constraint AOI button in the Region Growing Properties dialog AOI Source: Click on the appropriate radio button to select the AOI source to use for this operation: None File
Do not use an AOI. Click to use an existing AOI file. Select the file in the file name part below.
Viewer
Click to use the AOI defined in the Viewer.
AOI File: Use this file name part to select an AOI file. You must select the File option above to enable this option. The default file extension is .aoi.
OK Click to use the selected option and close this dialog. Cancel Click to close this dialog. Help Click to see this On-Line Help document.
5
Area of Interest
Area of Interest This dialog allows you to perform an operation upon a specific area of an image that is displayed in a Viewer. This dialog is opened when you click the From Viewer... option in another dialog.
Options: You have the following options for selecting an area of interest: Use Entire File Click to use the entire file regardless of the area visible in the Viewer. This is the default setting. Use Viewed Area
Click to use the area visible in the Viewer.
Use Inquire Box Click to display a white cursor box on the image. You can move and resize this box to select the area of interest. The Inquire Box Coordinates dialog is opened.
OK Click to use the selected area of interest and close this dialog. Cancel Click to close this dialog. Help Click to open this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
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AOI Tools
AOI Tools The AOI Tools enable you to select and create areas of interest (AOIs). These AOIs are often used as input to the Signature Editor prior to image classification. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. This tool palette is opened when you select Raster | Tools... from the Viewer menu bar or, if the AOI layer is the top layer in the Viewer, when you click the
icon in the Viewer tool bar.
To enter specific position and size parameters, you can press the space bar while drawing many AOI objects, which opens a dialog that allows you to enter precise coordinates and size information.
i
The Preference Editor allows you to select large or small tools. This dialog is opened if you have selected small tools.
Click to select, move, and resize AOI elements. Press the Shift key and use the pointer tool to select multiple elements.
Click to select all AOI elements that fall within the boundary of the rectangular marquee that you draw. To draw a perfect square, shift-left-hold when drawing.
Click to create a rectangular AOI. In the Viewer, drag diagonally from the upper left to the lower right corner to create the rectangular AOI. To draw a perfect square, shift-left-hold when drawing.
Click to create an elliptical AOI. In the Viewer, drag from the center to the lower right “corner” to create the desired ellipse. To draw a perfect circle, shift-left-hold when drawing.
Click to create a polygonal AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to close the polygon.
7
AOI Tools
Click to create a polyline AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to end the polyline.
Click to select a single pixel from which an AOI “grows” based on the parameters set in the Region Growing Properties dialog.
Click to create a point AOI.
Click to see this On-Line Help document.
Click to unlock the currently selected tool.
Click to lock the currently selected tool until another tool is selected.
Close Click to close this tool palette. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
8
AOI Tools (Large Format)
AOI Tools (Large Format) The AOI Tools enable you to select, create, and edit areas of interest (AOIs). These AOIs are often used as input to the Signature Editor prior to image classification. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. This tool palette is opened when you select Raster | Tools... from the Viewer menu bar or, if the AOI layer is the top layer in the Viewer, when you click the
icon in the Viewer tool bar.
To enter specific position and size parameters, you can press the space bar while drawing many AOI objects, which opens a dialog that allows you to enter precise coordinates and size information.
i
The Preference Editor allows you to select large or small tools. This dialog is opened if you have selected small tools and you have opted to combine tools and commands.
Click to select, move, and resize AOI elements. Press the Shift key and use the pointer tool to select multiple elements.
Click to select all AOI elements that fall within the boundary of the rectangular marquee that you draw. To draw a perfect square, shift-left-hold when drawing.
Click to create a rectangular AOI. In the Viewer, drag diagonally from the upper left to the lower right corner to create the rectangular AOI. To draw a perfect square, hold the shift key while dragging.
Click to create an elliptical AOI. In the Viewer, drag from the center to the lower right “corner” to create the desired ellipse. To draw a perfect circle, hold the shift key while dragging.
9
AOI Tools (Large Format)
Click to create a polygonal AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to close the polygon.
Click to create a polyline AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to end the polyline.
Click to select a single pixel from which an AOI “grows”, based on the parameters set in the Region Growing Properties dialog.
Click to create a point AOI.
Keep Tool Click to lock the current tool until another tool is selected. Close Click to close this tool palette. Help Click to see this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
10
AOI Tools and Commands
AOI Tools and Commands The AOI Tools enable you to select, create, and edit areas of interest (AOIs). These AOIs are often used as input to the Signature Editor prior to image classification. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. This tool palette is opened when you select AOI | Tools... from the Viewer menu bar or, if the AOI layer is the top layer in the Viewer, when you click the
icon in the Viewer tool bar.
To enter specific position and size parameters, you can press the space bar while drawing many AOI objects, which opens a dialog that allows you to enter precise coordinates and size information.
i
The Preference Editor allows you to select large or small tools. This dialog is opened if you have selected small tools and you have opted to combine tools and commands.
Click to select, move, and resize AOI elements. Press the Shift key and use the pointer tool to select multiple elements.
Click to select all AOI elements that fall within the boundary of the rectangular marquee that you draw. To draw a perfect square, shift-left-hold when drawing.
Click to create a rectangular AOI. In the Viewer, drag diagonally from the upper left to the lower right corner to create the rectangular AOI. To draw a perfect square, hold the shift key while dragging.
Click to create an elliptical AOI. In the Viewer, drag from the center to the lower right “corner” to create the desired ellipse. To draw a perfect circle, shift-left-hold when drawing.
Click to create a polygonal AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to close the polygon.
Click to create a polyline AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to end the polyline.
11
AOI Tools and Commands
Click to select a single pixel from which an AOI “grows” based on the parameters set in the Region Growing Properties dialog.
Click to create a point AOI.
Click to undo the last edit. Select multiple times to undo a series of edits (back to the last saved version of this AOI layer).
Click to delete the selected element(s). A copy is kept in a copy/paste buffer.
Click to reshape a selected polygon or polyline:
♦ left-hold to move a vertex of the polygon or polyline; ♦ middle-click to add a vertex to the polygon or polyline; ♦ shift-middle-click to add or remove a vertex from the polygon or polyline; ♦ left-hold on any side of a polygon to move it without rotating. To quit reshape mode, click outside the element or select another element.
Click to combine the selected elements into a group element.
Click to break a group element into single elements.
Click to delete all raster areas from the AOI layer. Raster areas are created by using the AOI | Copy Selection to AOI... option of the Viewer menu bar from a pseudo color image.
Click to invert a region grown area so that everything not in the region grow is selected as an AOI. This option is helpful for selecting island polygons.
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AOI Tools and Commands
Click to bring up the Properties dialog for the selected element:
♦ Ellipse ♦ Rectangle ♦ Polygon/Polyline ♦ Point ♦ Group Click open the AOI Styles dialog.
Click to open the Region Growing Properties dialog.
Click to add the selected Raster, Vector, or Annotation object to the top AOI layer in the current viewer.
Click to link the selected AOI(s) to the specified window.
Click to create a new digitizing tablet configuration. The Tablet Setup dialog is opened.
Click to use an existing tablet configuration. The Map Setup dialog is opened along with the Tablet Status dialog.
Click to unlock the currently selected tool.
Click to lock the currently selected tool until another tool is selected.
Close Click to dismiss the AOI tools. Click to see this On-Line Help document.
13
AOI Tools and Commands
➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
14
AOI Tools and Commands (Large Format)
AOI Tools and Commands (Large Format) The AOI Tools enable you to select, create, and edit areas of interest (AOIs). These AOIs are often used as input to the Signature Editor prior to image classification. See Rules for Pixel Inclusion within Polygons for a discussion of how IMAGINE determines if a pixel is included within an AOI polygon. This tool palette is opened when you select AOI | Tools... from the Viewer menu bar or, if the AOI layer is the top layer in the Viewer, when you click the
icon in the Viewer tool bar.
To enter specific position and size parameters, you can press the space bar while drawing many AOI objects, which opens a dialog that allows you to enter precise coordinates and size information.
i
The Preference Editor allows you to select large or small tools. This dialog is opened if you have selected small tools and you have opted to combine tools and commands.
Click to select, move, and resize AOI elements. Press the Shift key and use the pointer tool to select multiple elements.
Click to select all AOI elements that fall within the boundary of the rectangular marquee that you draw. To draw a perfect square, hold the Shift key when drawing.
Click to create a rectangular AOI. In the Viewer, drag diagonally from the upper left to the lower right corner to create the rectangular AOI. To draw a perfect square, hold the shift key while dragging.
Click to create an elliptical AOI. In the Viewer, drag from the center to the lower right “corner” to create the desired ellipse. To draw a perfect circle, hold the Shift key while dragging.
15
AOI Tools and Commands (Large Format)
Click to create a polygonal AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to close the polygon.
Click to create a polyline AOI. In the Viewer, click to add each vertex. Double-click or middle-click (depending upon how your preferences are set) to end the polyline.
Click to select a single pixel from which an AOI “grows”, based on the parameters set in the Region Growing Properties dialog.
Click to create a point AOI.
Click to undo the last edit. Select multiple times to undo a series of edits (back to the last saved version of this AOI layer).
Click to delete the selected element(s). A copy is kept in a copy/paste buffer.
Click to reshape a selected polygon or polyline:
♦ hold to move a vertex of the polygon or polyline; ♦ middle-click to add a vertex to the polygon or polyline; ♦ shift-middle-click to add or remove a vertex from the polygon or polyline; ♦ hold on any side of a polygon to move it without rotating. To quit reshape mode, click outside the element or select another element.
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AOI Tools and Commands (Large Format)
Click to combine the selected elements into a group element.
Click to break a group element into single elements.
Click to delete all raster areas from the AOI layer. Raster areas are created by using the AOI | Copy Selection to AOI... option of the Viewer menu bar from a pseudo color image.
Click to invert a region grown area so that everything not in the region grow is selected as an AOI. This option is helpful for selecting island polygons
Click to bring up the Properties dialog for the selected element:
♦ Ellipse ♦ Rectangle ♦ Polygon/Polyline ♦ Point ♦ Group
Click open the AOI Styles dialog.
Click to open the Region Growing Properties dialog.
17
AOI Tools and Commands (Large Format)
Click to add the selected Raster, Vector, or Annotation object to the top AOI layer in the current viewer.
Click to link the selected AOI(s) to the specified window.
Click to create a new digitizing tablet configuration. The Tablet Setup dialog is opened.
Click to use an existing tablet configuration. The Map Setup dialog is opened along with the Tablet Status dialog.
Click to unlock the currently selected tool.
Click to lock the currently selected tool until another tool is selected.
Close Click to dismiss the AOI tools. Click to see this On-Line Help document.
➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
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AOI Commands
AOI Commands These AOI (area of interest) commands enable you to control the placement and properties of AOI elements in the Viewer. This dialog cannot be reached using the IMAGINE user interface. It can only be accessed through EML application functions commands. These commands are also found in AOI menu on the Viewer, and in the AOI Tools and Commands palette.
☞ You can also display these commands as icons in the AOI tool palette. This option is set in the viewer category of the Preference Editor.
Cut Select to delete the selected element(s). A copy is kept in a copy/paste buffer. Delete Raster Select to delete all raster areas from the AOI layer. Raster areas are created by using the AOI | Copy Selection to AOI... option of the Viewer menu bar from a pseudo color image. Group Select to combine the selected elements into a group element. Ungroup Select to break a group element into single elements. Reshape Select to reshape a selected polygon or polyline: ♦ hold to move a vertex of the polygon or polyline; ♦ middle-click to add a vertex to the polygon or polyline; ♦ shift-middle-click to add or remove a vertex from the polygon or polyline; ♦ hold on any side of a polygon to move it without rotating. To quit reshape mode, click outside the element or select another element.
Invert Polygon Select to invert a region grown area so that everything not in the region grow is selected as an AOI. This option is helpful for selecting island polygons.
Undo Select to undo the last edit. Select multiple times to undo a series of edits (back to the last saved version of this AOI layer).
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AOI Commands
Properties... Select to bring up the Properties dialog for the selected element: ♦ Ellipse ♦ Rectangle ♦ Polygon/Polyline ♦ Point ♦ Group Close Click to close this dialog. Help Click to see this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
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AOI Styles
AOI Styles This dialog enables you to set default styles for areas of interest (AOIs). It is opened when you select AOI | Styles... in the Viewer menu bar. It is also opened when you click the the AOI Tools palette.
icon on
Chaser: Foreground Width: Enter the width (in pixels) of the foreground of the chaser line that is opened around AOIs. A larger number will make the dashes in the chaser longer. A smaller number will make the dashes smaller. The chaser line is made up of two parts: the foreground line and the background line. These lines can have different widths and colors to achieve the desired look. When both the foreground and background widths are the same size, but different colors, the line is opened to blink and rotate like marquee lights Color: Click on this color patch to select the color for the foreground line of the chaser. Background Width: Enter the width (in pixels) of background chaser line. Color: Click on this color patch to select the color for the background line of the chaser. Interval: Enter the chaser time interval in milliseconds. The smaller the number, the faster the chaser will blink. Thickness: Enter the chaser line thickness.
Polygon: Fill: Click to fill the AOI objects with a solid color. Fill Color: Click on this color patch to select the color for polygon fill.
Apply Click to apply the AOI style. Close Click to close this dialog. Help Click to see this On-Line Help document.
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AOI Styles
➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
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Region Growing Properties
Region Growing Properties This dialog enables you to set parameters that affect region growing AOI selection. It is opened when you select Seed Properties... from the AOI, Vector, or Annotation menus in the Viewer menu bar. It also opens when you click on the
icon in the Annotation Tools palette.
Neighborhood: This option determines which pixels will be considered contiguous to the seed pixel. Any neighbor pixel that meets all selection criteria is accepted and thus, itself, becomes a seed pixel.
If four neighbors are searched, then only those pixels above, below, to the left, and to the right of the seed pixel are considered contiguous.
If eight neighbors are searched then the diagonal pixels are also considered contiguous.
Geographic Constraints: This group allows you to enter constraints for the AOI. You can select only one option or use both options. Area: Click to constrain by region area in pixels. Enter the maximum size of the AOI and then click on the accompanying popup list to select units as either # pixels, hectares, acres, or sq. miles. Distance: Click to constrain the AOI by specifying a distance from the seed pixel. Enter the distance and then click on the accompanying popup list to select distance units as either pixels, meters, or feet.
Spectral Euclidean Distance: Enter the Euclidean spectral distance in digital number (DN) units on which to accept pixels. The pixels that are accepted will be within this spectral distance from the mean of the seed pixel.
Grow at Inquire Click to grow a new region using the current properties. Set Constraint AOI... Click to specify an bounding AOI for the region grow. Options... Click to set other region growing parameters. The Region Growing Options dialog is opened.
Redo Click to redo the last region with same seed coordinate.
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Region Growing Properties
Invert Click to invert the selection to select islands within the region grow area. Close Click to close this dialog and save the selected parameters. Help Click to see this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For step-by-step instructions on selecting AOIs for training samples, see the Classification section of the ERDAS IMAGINE Tour Guides manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
24
Region Grow Options
Region Grow Options This dialog enables you to set additional parameters that affect region growing. It is opened when you click Options... in the Region Growing Properties dialog.
Include Island Polygons Click to enable the grow region to include island polygons. Update Region Mean Click to update the region mean as the region grows. Buffer Region Boundary Click to buffer the boundary of the region. This option is useful when you are selecting AOIs for editing DEM data, so that you can avoid sudden changes in elevation. Close Click to close this dialog. Help Click to see this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of this manual.
➲ For step-by-step instructions on selecting AOIs for training samples, see the Classification section of the ERDAS IMAGINE Tour Guides manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
25
Save AOI As ...
Save AOI As ... This dialog enables you to save an AOI layer to a file. It appears when you left-hold File | Save AOI Layer As... in the Viewer menu bar when an AOI layer is displayed in the Viewer, or whenever ERDAS IMAGINE allows you to save AOI layers.
Save AOI as: Use this file name part to enter the name of the AOI. The .aoi extension is added automatically.
Selected Only Click to save only the AOIs which are selected in the Viewer. If this option is not checked, then all AOIs will be saved. OK Click to save the AOI(s) and close this dialog. Cancel Click to close this dialog without saving the AOI(s). Help Click to see this On-Line Help document. ➲ For steps on how to create an AOI from a raster, vector, or annotation layer, see the Create AOI section of the on-line AOI manual.
➲ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.
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