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Author Topic: Holes in dense pointcloud  (Read 7483 times)

aletopo

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Holes in dense pointcloud
« on: May 11, 2015, 09:14:45 AM »
Hi all

I'm processing a dataset with about 1200 images (16 MP resolution) on a single workstation with 64 GB RAM (Agisoft version 1.1.6 build 2038 64 bit).
Image alignment takes quite a long time but is successful. However the dense point cloud (high density, mild filtering) shows holes, i.e. there are areas with no points at all. Total number of points is about 300 million, effective overlap 5.69. If I take a selection of images or split the project into chunks, holes mostly disappear (or appear at other locations). Processing the dataset with another software delivers good results.
Is this a common problem?

Alexey Pasumansky

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Re: Holes in dense pointcloud
« Reply #1 on: May 11, 2015, 11:12:31 AM »
Hello aletopo,

Holes in the dense cloud may be related to the insufficient number of matching points between the overlapping images in the related area. I can suggest to raise the tie-point limit value from 1000 (default) to 10 000, for example.
Best regards,
Alexey Pasumansky,
Agisoft LLC

aletopo

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Re: Holes in dense pointcloud
« Reply #2 on: May 11, 2015, 05:25:46 PM »
Hi Alexey,

Thank you for your reply. Wouldn't a rise of tie-point limit value worsen the problem? As far as I can read from the manual, higher tie-point limit can lead to less photos being considered for depth map generation.
I can't imagine the software to find insufficient number of matching points within an urban area while having no problems with uniform fields. Furthermore there are no holes within the sparse point cloud.

yelnam

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Re: Holes in dense pointcloud
« Reply #3 on: May 20, 2015, 09:18:35 PM »
Howdy,

I have the same problem.  Some clarification would be great, as the manual p. 12 does imply that a lower tie point limit would be better to avoid holes in the dense point cloud.

Thanks!

Pawel

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Re: Holes in dense pointcloud
« Reply #4 on: May 26, 2015, 12:35:29 PM »
Hello
I've had the same problem with dence point cloud. Raising tie-point limit to 10 000 resolve the issue  ;)

bigben

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Re: Holes in dense pointcloud
« Reply #5 on: May 27, 2015, 12:33:06 AM »
The points in the sparse point cloud where holes are appearing in the dense cloud may be noisy. Reducing the filtering for the dense cloud may fill the holes, but the resulting mesh may be distorted.