Can't Select points for Point Pair Picking

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dvs
Posts: 1
Joined: Wed Nov 15, 2017 7:26 am

Can't Select points for Point Pair Picking

Post by dvs »

Using CloudCompare 2.9.1 64-bit, Win10
I'm trying to align two clouds using Point Pair Picking. The clouds were generated by PhotoScan from two different photo sets of the same scene.

Sometimes I can easily pick points in the reference and align clouds, but at other times, it's nearly impossible to pick the point I want in either the reference or align cloud.

The meshes are sparse pointclouds of trees (see pics).

I turned on vertices in the meshes and expanded the point size, set the search radius r = 200, 400, 999 (it doesn't matter) and nudge the cloud a little via the RTmousebutton to see the vertices.
I then click on those vertices and either nothing happens or reference/aligned point labels are added elsewhere from where i'm clicking.
When I start clicking frantically in small random movements around the vertex I want to tag, I just get a large number of erroneous point labels, which I have to manually delete and start over.
If I pull back the viewpoint away from the surface, I always see that the point labels had landed directly behind the closeup viewpoint that was looking at the surface. The erroneous points never land within field of view.

What is the secret to easily selecting points for point pair picking in sparse clouds?

(I just noticed that after restarting CC, it was easier to pick points, but I haven't run tests to confirm that's always true. )
CloudCompare_TreeCloseup.jpg
CloudCompare_TreeCloseup.jpg (226.46 KiB) Viewed 1733 times
CloudCompare_CloudCloseup.jpg
CloudCompare_CloudCloseup.jpg (181.01 KiB) Viewed 1733 times
daniel
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Re: Can't Select points for Point Pair Picking

Post by daniel »

The 'sphere' picking mechanism should only be used for real registration spheres (the big white spheres that are placed in the scene before scanning to help with the registration process). You should not activate this option in your case (as it actually looks for real spheres in the data).

On a mesh it should work without any problem. And on a cloud, make sure you hide the other entity (to avoid confusion).
Daniel, CloudCompare admin
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