Author Topic: GCP faster (Edited)  (Read 4584 times)


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GCP faster (Edited)
« on: November 06, 2012, 10:16:54 AM »
I have not seen this posted before... well may be not that unseen  :-[
My trick to save time when using GPC
1. Align your project without GCP
2. Create blank markers using the right mouse button on the corresponding branch of the object tree. You must create as many as you have in your project. (To save time, I recommend using the same naming scheme for field collection work. (Since pscan 0.9.x you can just go to step 6 as it creates automatically ALL empty markers during import, and then back to 3... sorry, I didn't notice)
3. Choose three of your project GCP that frame your work area.
4. Locate at least two pictures containing each of the three GCP
5. Place markers on each photo selected by using the right mouse button on the image. This makes six unassisted marker placement.
6. (skip if done before) Go to the Control Points dialog, define its coordinate system using the settings button and then import an ASCII file containing: name, x, y, z. for each GCP
7. Click the Update button and observe gray markers for all GCP on their tentative locations.
8. select one marker Filter images by marker and refine the position of each gray marker dragging it to its exact position. Occasionally you can click Update to improve the absolute orientation of the model and thus the remaining gray markers will approximate better to their precise positions.
9. repeat step 8 with all of your GCP.
I hope this hint help you to save some time!

I take this point to suggest AGISOFT team to improve the gray marker's refining workflow. I hate that they move when I just wanted to accept their current position.
In my opinion, when you click on the marker, you could open a magnifier window with accept and skip icons where the user could reposition the marker by dragging, validate the gray position as is calculated and turn it blue, or skip to close the magnifier letting marker remain in gray status. (Options for magnifier might be: magnification factor, show upsampled and border/contrast enhanced crop, crosshair cursor on button down, automatic target detection by key press... )


« Last Edit: November 06, 2012, 09:58:29 PM by LFA »