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Author Topic: Marker Refinement  (Read 1980 times)

WSurvey

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Marker Refinement
« on: March 02, 2017, 06:08:31 AM »
Once a marker is placed in a photo it seems it's intersection with a surface is used to approximately place markers in other photos. Sometimes the surface is not so good and the markers are placed well away from where they will end up. Ideally, once a marker is positively placed in two or more photos the rest of the markers should update their positions as we now have a reliable intersection with which to estimate the location of the remaining markers. This would speed up the process of moving markers to their final locations in larger image sets.

Excuse the post please if there is already a way to do this, but I cannot find it.

bortoman

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Re: Marker Refinement
« Reply #1 on: March 02, 2017, 09:07:23 AM »
Hi,
I suggest you try the following:
- place the markers immediately after image alignment (before generating dense cloud or mesh)

This way, after the first 2 pictures the assumed position is shown with the gray "smoke" symbol (or however it's called) and it adjusts better and better as you proceed...

After placing all the markers in all the photos you optimize alignment and proceed with the workflow, this has given me the best results.

Alexey Pasumansky

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Re: Marker Refinement
« Reply #2 on: March 02, 2017, 09:26:48 AM »
Hello WSurvey,

I think you need to enable "Refine marker projections based on image content" option in the Preferences window of PhotoScan. The unpinned projections (blue flags) will be automatically adjusted basing on pinned projections (green flags). The feature works better if the marker is placed in some contrast point.
Best regards,
Alexey Pasumansky,
AgiSoft LLC

WSurvey

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Re: Marker Refinement
« Reply #3 on: March 02, 2017, 09:55:32 AM »
Thanks for the suggestions. I'll give them a go.

I've noticed that perhaps Photoscan generates a hidden surface from the sparse cloud immediately after orientation??? I've placed a single marker after orientation and gotten grey markers in the other photos approximately where a surface would be. Which was a nuisance for me because I was trying to mark an elevated point and so the grey markers were well away from where I wanted them. I didn't have a mesh or DEM, and the only way to stop the behavior was to deleted the sparse cloud, mark my elevated points with guide lines, and reorient.

Alexey Pasumansky

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Re: Marker Refinement
« Reply #4 on: March 02, 2017, 12:07:00 PM »
Hello WSurvey,

In the version 1.3.0 PhotoScan is trying to intersect the ray related to the marker projection with the surface (point cloud and dense cloud now may act as a surface in this case).

If you do not wish to see " blue flags" you can create an empty marker instance in the Workspace pane and then using Place Marker in Photo view mode instead of Create Marker.
In the next version update the will be a New Marker option in the Place Marker menu, so you wouldn't need to create a new instance manually in the Workspace pane.
Best regards,
Alexey Pasumansky,
AgiSoft LLC

GrinGEO

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Re: Marker Refinement
« Reply #5 on: November 21, 2017, 01:53:24 PM »
I have an adivce too...

when importing GCP from CSV file that are not in WGS84 but something else like Gauss Kruger ecc., the Ortho View shows the markers aproximately on the right position. Is there no way to refine the position of the markers in the Ortho View?

Becouse from the Orthoview if I select pictures from point it does not show up the right pictures (probably becouse markers are in Gauss Kruger system).
any help on this?