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Author Topic: TiePoint limit for dense cloud matching between two photos  (Read 3084 times)

picare

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TiePoint limit for dense cloud matching between two photos
« on: September 18, 2019, 11:50:33 AM »
I have photos with overlap, but very few Tie Points are linking some photos:
Computing the Tie points with the parameters 40000/4000 gives veru few points, 150000/150000 gives a little more, and 0/0 gives no more than 150000/150000.
The photos are very old photos (film camera) with a lot of overlap but maybe too much angle.

Te resulting matches between two photos of the project with lot of overlap gives sometimes 200-400 points, and sometimes 40.
The dense pointcloud is not generated for the photos with less than 100 points. This gives a big hole in my 3D model.

A partial solution is resizing the bounding box in the area whith no dense cloud, and it works sometimes... it gives a nice point cloud, but it is not the best to do (long work, merging, filtering, and sometimes gives "no resolution" error) and complicated to use with the meshing method based on depth maps.

Is it a tweak option to allow Metashape to compute the depth maps and so, the dense cloud, for the overlapping photos with less than 100 points ? Can we reduce this parameter to 20 or 30 points?
« Last Edit: September 18, 2019, 12:17:02 PM by picare »

Alexey Pasumansky

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Re: TiePoint limit for dense cloud matching between two photos
« Reply #1 on: September 20, 2019, 01:11:02 PM »
Hello picare,

You can adjust this minimal threshold with the main/depth_point_threshold.
Best regards,
Alexey Pasumansky,
Agisoft LLC

picare

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Re: TiePoint limit for dense cloud matching between two photos
« Reply #2 on: September 20, 2019, 02:25:53 PM »
Perfect, that's solving this problems!

Thanks,

Regards,

Pierre

Alexey Pasumansky

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Re: TiePoint limit for dense cloud matching between two photos
« Reply #3 on: September 20, 2019, 08:28:31 PM »
Hello Pierre,

But do not forget to set the value back to 100 (or remove the tweak), when you are back to the normal projects, otherwise the processing may take longer time and you could get higher noise on the depth maps and dense cloud.
Best regards,
Alexey Pasumansky,
Agisoft LLC

picare

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Re: TiePoint limit for dense cloud matching between two photos
« Reply #4 on: December 26, 2019, 07:08:27 PM »
Hi Alexey, is it similar options for the alignment process?

I have lot of invalid matches whereas they seem to be valid.
Unfortunalety, there is not a lot of points.

Moreover, how is it possible to have maybe just 10 grey points on one image, whereas 30000 SIFT points are detected?

Regards,

Pierre

picare

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Re: TiePoint limit for dense cloud matching between two photos
« Reply #5 on: January 21, 2020, 04:58:53 PM »
Hello picare,

You can adjust this minimal threshold with the main/depth_point_threshold.

Hi,

It seems this tweak is no more working on Metashape 1.6 and 1.6.1 ( main/depth_point_threshold )
The point cloud we have with the value at 10 instead of 100 give the same result.

Did you remove or change the name of this tweak?

Alexey Pasumansky

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Re: TiePoint limit for dense cloud matching between two photos
« Reply #6 on: January 21, 2020, 07:10:24 PM »
Hello Pierre,

This tweak should be still working as intended.
Best regards,
Alexey Pasumansky,
Agisoft LLC