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Author Topic: sparse cloud clean, dense cloud mess  (Read 468 times)

archim

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sparse cloud clean, dense cloud mess
« on: September 11, 2021, 09:08:40 PM »
Hey. I wondered why the dense cloud seems to be using points i deleted in the sparse cloud? I created the sparse cloud, then removed and cleaned a lot of points but after calculating the dense cloud, all deleted points are back in dense cloud view, messing everything up. Check my images for claryfication.

Bzuco

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Re: sparse cloud clean, dense cloud mess
« Reply #1 on: September 12, 2021, 11:01:34 AM »
From the PDF manual: The sparse point cloud represents the results of image alignment and will not be directly used in  further  processing...
Delete sparse points make sense only using gradual selection function(from Model menu), which will results in better(more precise) camera positions. After selecting and deleting points using gradual selection tool, you need to use optimize cameras function from Tools menu to update camera positions.

If you want to clean dense cloud points, you can select them by color, by Mask, or filter them by confidence.(Tools-Dense cloud menu). Or you can export dense cloud to Cloud Compare program and apply SOR function which will remove points representing noise in cloud.

archim

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Re: sparse cloud clean, dense cloud mess
« Reply #2 on: September 12, 2021, 09:27:04 PM »
From the PDF manual: The sparse point cloud represents the results of image alignment and will not be directly used in  further  processing...
Delete sparse points make sense only using gradual selection function(from Model menu), which will results in better(more precise) camera positions. After selecting and deleting points using gradual selection tool, you need to use optimize cameras function from Tools menu to update camera positions.

If you want to clean dense cloud points, you can select them by color, by Mask, or filter them by confidence.(Tools-Dense cloud menu). Or you can export dense cloud to Cloud Compare program and apply SOR function which will remove points representing noise in cloud.
Thank you very much. So as far as i understand: Sparse cloud modifications will only impact the final result, if the modifications change the camera alignements.

Bzuco

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Re: sparse cloud clean, dense cloud mess
« Reply #3 on: September 13, 2021, 07:42:48 AM »
Yes, sparse cloud consists from points with different values of errors. You can see it if you start select points using gradual selection sliders. Points with higher error values can potentially cause deviations in camera positions/rotations, which could later results in deformations in shape of dense cloud/mesh.

Alexey Pasumansky

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Re: sparse cloud clean, dense cloud mess
« Reply #4 on: September 16, 2021, 08:57:43 PM »
Hello archim,

Could you try to build the mesh using the depth maps source option for this project and check, whether it gives you clear and accurate result? Depth maps based mesh generation includes additional noise filtering algorithms that should neglect the observed noise in the dense cloud.
Best regards,
Alexey Pasumansky,
Agisoft LLC