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Classification of points from RGB

Posted: Mon Feb 17, 2025 10:31 am
by Adanos
Hello,
I am trying to extract some specific points from a cloud that can be classified only from RBG values.
Those points I am interested in are actually 3D objects that are "plunged" into a background.
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1.png (302.76 KiB) Viewed 9527 times
As you can see, those objects are actually displayed as greenish points inside blue points. As the object becomes more clear compared to the background, the intensity of the green increases.
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2.png (172.22 KiB) Viewed 9527 times
Is it possible to classify and divide those points from the backgorund? I would like to include the points that have a minimum green intensity, not just every point that display a greenish shade.

Thank you in advance.

Re: Classification of points from RGB

Posted: Tue Feb 18, 2025 10:32 am
by daniel
Sorry, I can't see the screenshots.

Re: Classification of points from RGB

Posted: Tue Feb 18, 2025 11:35 am
by Adanos
Hello Daniel,
Thank you for the reply, I updated the post with the screenshots.

Re: Classification of points from RGB

Posted: Wed Feb 19, 2025 7:42 am
by daniel
Ah, in this case the most obvious way to do it is to use 'Edit > Colors > Convert to scalar fields' (you can only choose to export the Green components, but you could also use the other components to pre-select points with low blue and red values).

Then use the scalar fields to filter the point. You can do it interactively (with the scalar field display properties section in the cloud properties once highlighted). Play with the min and max displayed values (there's also an option to hide the points falling outside of this range in the second pannel).

Eventually, you can use 'Edit > Scalar fields > Filter by value' to extract the corresponding points as a new cloud.

And there's another option: the Colorimetric segmenter plugin (https://www.cloudcompare.org/doc/wiki/i ... r_(plugin)). Sadly there's no real documentation yet for this plugin, but you can try to play with it, it's pretty straightforward if I remember well.

Re: Classification of points from RGB

Posted: Thu Feb 20, 2025 3:01 am
by Adanos
Thanks you Daniel, will give It a try!.