Assign poor polygons
Assign poor polygons command is used to define areas in images of one camera that should be avoided in rectification processes. Such areas may be caused, for examples, by dust on the camera lens or by other small artifacts which lead to small flaws at the same location in all images.
Such areas are marked in one raw image by a polygon. Then, the polygon can be defined as “poor polygon” for a camera in the Camera dialog. Areas inside poor polygons are excluded from automatic tie point and color point searches. In rectification processes, they are filled from other images whenever possible.
The polygons are stored in the camera calibration files. The coordinates of the vertices of the polygons are listed for each polygon separately in the calibration file of the effected camera.
To assign a poor polygon:
1. Select Manage Raster References tool in order to open the Manage Raster References window of TerraPhoto.
2. Attach a raw image as raster reference using Attach files command from the File pulldown menu.
3. Select Modify attachment command from the Edit pulldown menu.
4. In the Modify attachment dialog, define the following values:
| Easting origin = 0.0000 | Pixel size = 1.00000 |
| Northing origin = 0.0000 | Pixel size = 1.00000 |
5. Select Fit / Selected command from the View pulldown menu. Place a data click inside a CAD file top view in order to display the image.
6. Digitize a polygon around the area that should not be used from the images of the camera. Any CAD platform tool for creating shape elements can be used.
You may create several polygons that can be defined as poor polygons in one step.
7. Select the polygon using any Selection tool of the CAD platform.
8. Select Define Camera tool in order to open the Camera dialog.
9. Select the correct camera name in the Camera field.
10. Select Assign poor polygons command from the Tools pulldown menu.
This defines the selected polygon as poor polygon. The number of Poor areas is displayed in the Camera dialog.
11. Select Save or Save as commands from the File pulldown menu in order to save the polygons into a camera calibration file.
