relative_orientation

#Image Control Stage 1 - Relative Orientation

In the Relative Orientation stage we will remove the Y-parallax between the stereo images. Y-parallax is separation of the stereo images in the Y (up-and-down) direction.

##Multi-Sensor Triangulation Setup

1. From the SOCET SET menu bar, select Preparation > Multi-Sensor Triangulation.

   

2. Press the box next to the Triangulation file field to bring up a file selection window.

3. Enter <ProjectName>_Relative as the name of triangulation file and press Save.

4. Press Setup.

5. In the Setup window, press Add.

   Note that in the Setup Window, the Ground Point File: (to be created) will automatically be named after the project name.

6. In the Strip ID Sequence box, use the default value of 1, and press OK.

7. You will be prompted to Select Support Files. Do this by highlighting each image in the Available list and moving them to Selected list via the arrow buttons. Press OK when done.

8. The selected images are now listed in the Setup window. Select the nadir-most image, and press Image Data….

9. In the Image Data window:

   a. make sure no check boxes are checked in the Adjust field.

   b. Turn on radio button Selected Image(s) Only in the Apply To section.

   c. Press “OK”.

   Note:

   1. Not allowing any parameters to adjust holds this image to it’s a-priori position and pointing.

   2. Please ignore the values listed in the Accuracy field, as they may not be applicable to the setup in certain cases

10. Go back to the Setup window. Select the Support file of the other image, and press Image Data….

11. In the Image Data window:

    a. Turn on the check boxes for the parameters listed below, and enter the corresponding accuracy values. (All other parameters are off. If a parameter is checked, it will be allowed to adjust. If it is not checked, it will remain unchanged when the triangulation is run.)

    b. Turn on radio button Selected Image(s) Only in the Apply To section.

    c. Press OK.

    Parameter	Accuracy
    IT pos. bias	100 m
    CT pos. bias	100 m
    Radial pos. bias	10 m
    IT vel. bias	13 m/s
    CT vel. bias	13 m/s
    Radial vel. bias	1.3 m/s
    Kappa bias	0.1 degree

12. Press OK in the Setup window.

    

13. Select File > Save Triangulation File in the Automated Triangulation window.

Tie Point Distribution

Using Interactive Point Measurement (details below), we will measure two “tie points” per region, as distributed in 8 regions shown here, for a minimum of 16 points. This point distribution is called “Buddy Points”, and aids in highlighting poor image measurements when solving a bundle adjustment.

NOTE: We want to convert as many of these tie-points to z-only control in the Vertical Adjustment to MOLA stage, so when possible avoid steep slopes areas.

Interactive Point Measurement Setup

1. Ensure that the View 1 window in the stereo display is set for stereo mode.
2. Be seated squarely in front of the stereo display (with stereo viewing glasses).
3. Press Interactive Point Measurement from the Automated Triangulation window.
4. Press Settings in the Interactive Point Measurement (IPM) window.
5. In the Settings for IPM window, check the Auto Img List box, then press “Close”.

Manual Tie Point Measurement

1. In the IPM window:

   a. Right Click in the Point ID field.

   b. Select “Add” in the pop-up window.

   

2. On the TopoMouse, use the zoom out button (repeatedly), to view full extents of the stereo model.

   

3. Move cursor to first (or next) region for tie point measurement.

   

4. Use TopoMouse “Zoom in” button (repeatedly) to set view to approximately 8:1 ratio.

   

5. Locate an area where terrain is relatively continuous with minimal slope, and move extraction cursor to that location.

   

6. In the IPM window, lock the Left image by checking its Lock box.

   

7. Clear parallax by moving the Right image only and place the extraction cursor on the ground. You may use the Z wheel to fine-tune the height adjustment of the extraction cursor after Y-parallax is removed.

   

   Note: You need to practice the placement of the cursor on the ground several times, until you have clear sense of when it is above or below the ground. See Appendix: A-3 Placing Dot on the Ground.

8. Use the TopoMouse “Zoom In” button (repeatedly) to set view to 1:1 ratio.

   

9. In the IPM window, Unlock the Left image by unchecking its Lock box.

   

10. Refine the extraction cursor position to a highly discernible location that is representative of surrounding terrain and free of high relief or slope. Do not measure edges of shadows, because shadows “move” between image scenes, and the extraction cursor will not be truly on the ground.

    

11. In the IPM window, lock the Left image by checking its Lock box.

    

12. Refine the parallax removal (at ground level) by moving the Right image only. In other words, put the dot on the ground.

    Note: Experienced analysts with good stereo acuity to recognize when auto-correlation has correlated to a false positive result, may want to use the “Auto-Two” feature in this step. For details, see Appendix: A6.1 Auto Two Feature in IPM.

13. Press Sample on the IPM window to collect the point measurement.

    Note: Sample stores the measurement in computer memory only. After Sample is pressed, both images will be locked and measured.

    

14. Press Save on the IPM window to write the measurement to disk.

    

15. Start measurement of second (buddy) point in the same region:

    a. In the IPM window, Right Click in the Point ID field.

    b. Select Add in the pop-up window.

    

16. Move the extraction cursor to a new location in the current field of view.

17. In the IPM window, lock the Left image by checking its Lock box.

    

18. Refine the parallax removal (at ground level) by moving the Right image only. In other words, put the dot on the ground.

    Note: Experienced analysts with good stereo acuity to recognize when auto-correlation has correlated to a false positive result, may want to use the “Auto-Two” feature in this step. For details, see Appendix: A6.1 Auto Two Feature in IPM.

19. Press Sample on the IPM window to measure the (buddy) point.

    

20. Press Save on the IPM window to write the measurement to disk.

    

21. Go To: Step 1 of this section (17.4 Manual Tie Point Measurement), and repeat this procedure for each of the regions defined in 17.2 Tie Point Distribution.

22. After completing the measurement process for all 8 regions (16 points), press Close on the IPM window.

    

Bundle Adjustment

1. Return to the Automated Triangulation / Full Block menu in the MST, and activate the adjustment procedure by pressing Solve.

   

2. The Simultaneous Solve window will open, along with a Backup pop-up window. Press Yes on the pop-up to overwrite back up files.

   

3. In the Simultaneous Solve window, press Start to perform the bundle adjustment.

   

4. Once the adjustment is completed, the Simultaneous Solve window will be updated with a report of: Number of ground points generated, solution redundancy, and most importantly the RMS residual error (in Image pixels).

   An acceptable solution has (1) an Image (pixels) RMS of ~0.6 or less, and (2) no individual point measurement has an error greater than 2 pixels.

   Press “Results” in the “Simultaneous Solve” window to review the error of individual point measurements.

   

5. Points in the Residuals window are grouped by Type, and automatically sorted from highest to lowest residual. The Line and Sample fields list the point measurement errors in pixels. In a Relative Orientation, all points are Tie, so inspecting the top of the list will suffice.

   

6. If points have pixel errors greater than 2.0 pixels, SKIP TO: 17.6 Point Re-Measurement Process. Otherwise, continue to the next step.

7. If the image RMS is < ~0.6 pixels, and the maximum point measurement error is < 2.0 pixels, then press “Close” on the Multi-Sensor Triangulation Residuals window.

   

8. Press Save on the simultaneous solve window.

   

9. Press Yes on the Done pop-up window.

   

10. Press Close on the Simultaneous Solve window.

    

11. Select File > Exit on the Automatic Triangulation window.

    

    Relative Orientation is now complete!

12. SKIP: 17.6 Point Re-Measurement Process, GO TO: 17.7 Re-Load Images.

Point Re-Measurement Process

Continuing from 17.5 Bundle Adjustment…

1. On the Multi-Sensor Triangulation Residuals window, Left-Click on the Point ID(s) of the points to re-measure. (Hold the Control Key down to select multiple points.) Then press Re-measure Point(s)…. The re-measure point window will now open with the points selected.

   

2. Left-Click on the point to re-measure. The View 1 (stereo display) will display the current point measurement.

   

3. You have an option of relocating the point or clearing parallax:

   a. To relocate the point, Un-check the boxes in the Measured field for both images.

   b. To remove residual parallax, Un-check the Measured box for the Right image only.

   NOTE: Un-checking a Measured box will also un-Lock the image so it is free to move using the TopoMouse.

   

4. If you are re-locating the point, place the extraction cursor on the feature in the Left image that you would like to measure. Then Lock the Left image by checking the box in the Lock field for the Left image.

   

5. For either option (re-locating the point, or removing residual parallax), clear the parallax by moving the Right image only (i.e., put the dot on the ground).

6. Press Sample to collect the point measurement.

   

7. Press Save to write the measurement to disk.

   

8. Repeat re-measurement process for remaining points in the list. (Go back to step 2.)

9. Press Close after all points in the list are re-measured.

   

10. Press Close on the Multi-Sensor Triangulation Residuals window.

    

11. Press Start on the Simultaneous Solve window.

    

12. Press Residuals on the Simultaneous Solve window and make sure no individual point has an error greater than 2 pixels.

    

13. If there are points with larger than 2 pixel errors, Go To: Step 1 of this section (17.6 Point Re-Measurement Process) and further refine the measurements.

14. If the overall RMS < ~0.6 pixels, and all points have less than a 2 pixel error, we will exit Multi-Sensor Triangulation, and re-enter it in order to refresh the values stored in computer memory. First press Close on the Multi-Sensor Triangulation Residuals window.

    

15. Press Close on the Simultaneous Solve window. (Do Not Press Save.)

    

16. Press No to Saving Files in the Done pop-up window.

    

17. Select File > Exit on the Automatic Triangulation window.

    

18. From the SOCET SET menu bar, select Preparation > Multi-Sensor Triangulation.

    

19. Press Solve on the Automatic Triangulation window. (The triangulation file, ProjectName_Relative, should load automatically.)

    

20. Press Yes on the pop-up to overwrite back up files.

    

21. Press Start on the Simultaneous Solve window.

    

22. If the Image (pixels) RMS is < ~0.6 pixels, Press Save on the Simultaneous Solve window.

    

23. Press Yes on the Done pop-up window.

    

24. Press Close on the Simultaneous Solve window.

    

25. Select File > Exit on the Automatic Triangulation window.

    

    Relative Orientation is now complete!

Re-Load Images

After the Relative Orientation is complete, it is necessary to re-Load the images in order to view them with the results of the adjustment. You should now have a parallax-free stereo model.

1. From the SOCET SET menu bar, select File > Load Images.

   

2. In the Image Loader window, select the Left and Right Image to display by clicking on the image id in the Left and Right panels. (Selected images will be highlighted.)

   

3. Under View Control Panel settings: Ensure that View = 1 and that Load Point is selected.

   

4. Press Load.

   

5. Press Close”

   

##Backup Relative Orientation Results

At this point, it is prudent for the operator to backup the project data in order to have a re-entry point that does not require the re-measure of tie points.

1. From the SOCET SET menu bar, select USGS Tools > Backup Orientation.

   

2. Make sure the current project name is listed in the Project field. If not, press “Project” to select the current project, then press “OK”. (Otherwise the backup will be made in, and for, the wrong project!)

   

   

3. Replace Backup_0 with _Relative in the Local folder name field. The backup folder will be named <ProjectName>_Relative.

   

4. Press Backup.