VrOne
|
ON-LINE REFERENCE DOCUMENTATION CARDINAL SYSTEMS, LLC 386-439-2525 |
CORRELATE AREA (CorAre)
Type: VrTwo Batch Application
Automatically creates a grid of points inside an existing line using automatic image correlation.
Detailed Description
Automatically places grid points at ground locations inside an existing line. Points may be placed at any grid interval. The elevations of the points are determined using automatic image correlation techniques. The correlation algorithm may be fine tuned using several control parameters. Points may be placed on up to four different levels to quickly identify problem areas. The correlation works by selecting a point in the left stereo image and finding the matching point in the right stereo image. Based on the separation of the two points, a ground elevation is computed. NOTE: VrTwo must be running with a valid model open before using this application.
Local Commands
None
Parameters
The following parameters are used when correlating. Pressing button 7 allows the entry of these parameters.
Grid resolution (ground)
Defines the spacing between grid points. This parameter is entered in ground units.
Seed Point Layers
Defines the layers that seed points are located on. Seed points are existing symbols that have already been placed at ground elevations. The seed points are used to help guide the correlation routine to prevent points from being located off the ground.
Seed Line Layers
Defines the layers that seed lines are located on. Seed lines are existing lines that have already been placed at ground elevations. The seed lines are used to help guide the correlation routine to prevent points from being located off the ground.
0.9-1.0 Correlation Layer
Defines the layer that points will be placed in if their correlation factor is from 0.9 to 1.0. A layer value of 0 indicates that these points should not be placed.
NOTE: A correlation factor of 1.0 is a perfect match.
0.8-0.9 Correlation Layer
Defines the layer that points will be placed in if their correlation factor is from 0.8 to less than 0.9. A layer value of 0 indicates that these points should not be placed.
0.7-0.8 Correlation Layer
Defines the layer that points will be placed in if their correlation factor is from 0.7 to less than 0.8. A layer value of 0 indicates that these points should not be placed.
Below 0.7 Correlation Layer
Defines the layer that points will be placed in if their correlation factor is below 0.7. A layer value of 0 indicates that these points should not be placed.
Delete previous points
If this is on, then any points in the above four correlation layers will be deleted before the correlation process begins. This will prevent duplicate points when doing multiple correlation runs.
Symbol graphic pointer
Defines the graphic pointer that will be used when placing points.
Symbol Radius (in|mm)
Defines the radius that will be used when placing points.
Minimum elevation allowed
Any elevations found below this value will not be used. The current cursor elevation will return to the last good elevation or to the Index elevation if set.
Index elevation
If elevations are rejected because they fall outside the minimum and maximum allowed elevations, then the cursor elevation will return to this value. If this is 0.0, then the cursor elevation will return to the last good elevation.
Maximum elevation allowed
Any elevations found above this value will not be used. The current cursor elevation will return to the last good elevation or to the Index elevation if set.
Iterations per point
This controls how many points are correlated at each grid location. A value of 0 will result in only the single grid point being correlated. For each iteration, a ring of points surrounding the grid point are correlated. The point with the best correlation value is chosen for the final point placement. If a point is found with a correlation value greater than 0.9, the iteration process is stopped, and the point is chosen as the final location.
Ground shift per iteration (ground)
This controls how far each iteration ring is offset from the original grid point. This number should be at least as large as the pixel size in the stereo images.
The following illustration represents a single grid point with iterations set to 2. In this case a total of 35 points will be correlated at each grid location to determine the best correlation fit.
Correlation source window size
Window size of correlation source image patch. Will be matched to target image patch. Size is in pixels.
Correlation search width
Width of the correlation target image patch. Determines width of area to search at each grid point. Size is in pixels.
Correlation search height
Height of the correlation target image patch. Determines height of the area to search at each grid point. Size is in pixels. A value that is two pixels larger than source window size is recommended.
The following illustration represents a source image patch taken from the left image, and the target image patch taken from the right image for a single grid point. The source image patch will be compared to the target image patch until the matching pixel is found.
Maximum ground distance
Maximum allowed distance in ground coordinates. If distance that cursor must move from the exact grid location is greater than this value, then correlation is rejected.
Maximum elevation change
Maximum allowed elevation change. When each grid point is correlated, an approximate elevation is used that is based on the last successfully placed point elevation, the index elevation if the last point was invalid, or the elevation from the seed data if available. If the elevation of the final correlated point is greater than the initial elevation approximation, then the correlation is rejected. When using seed points and lines, this value should be made smaller to keep the correlated points close to the seed surface.
Button Assignments
Correlate Area – Lock on
Allows searching for a line to edit.
|
|
Button
|
Description |
|
1 |
Id
line |
Identifies line to correlate. Displays Accept Menu |
|
2 |
|
|
|
3 |
|
|
|
4 |
|
|
|
5 |
|
|
|
6 |
|
|
|
7 |
Enter params |
Allows entry of correlation parameters. Displays parameters dialog. |
|
8 |
|
|
|
9 |
|
|
|
* |
|
|
|
0 |
|
|
|
# |
End |
Ends application |
Correlate Area – Accept
Allows user to accept or reject selected line.
|
|
Button
|
Description |
|
1 |
Accept
line |
Accepts line, begins correlation, and display Stop menu. |
|
2 |
Reject line |
Rejects line and displays Lock on menu. |
|
3 |
|
|
|
4 |
|
|
|
5 |
|
|
|
6 |
|
|
|
7 |
|
|
|
8 |
|
|
|
9 |
|
|
|
* |
|
|
|
0 |
|
|
|
# |
|
|
Correlate Area – Stop
Allows searching for a line to edit.
|
|
Button
|
Description |
|
1 |
|
|
|
2 |
Stop |
Stops current correlation and displays Lock on menu. |
|
3 |
Pause |
Pauses current correlation and displays Resume menu. |
|
4 |
|
|
|
5 |
|
|
|
6 |
|
|
|
7 |
|
|
|
8 |
|
|
|
9 |
|
|
|
* |
|
|
|
0 |
|
|
|
# |
|
|
Correlate Area – Resume
|
|
Button
|
Description |
|
1 |
Resume |
Resumes previously paused correlation and display Stop menu. |
|
2 |
|
|
|
3 |
|
|
|
4 |
|
|
|
5 |
|
|
|
6 |
|
|
|
7 |
|
|
|
8 |
|
|
|
9 |
|
|
|
* |
|
|
|
0 |
|
|
|
# |
End |
Ends correlation and display Lock on menu. |