Cloud-mesh distance function not working properly

[nenrique]

Hi guys,

I'm having a problem in cloud compare with a few of my meshes. Basically i am trying to fit a plane and then calculate cloud-mesh distances for the purpose of creating a digital elevation model, where i can show topographic highs as reds, topographic lows as blues etc. But there is an issue happening when i use the cloud-mesh distance function: it thinks everything is pretty much the same distance from the plane i fitted. So even though there is topographic variation, everything is coming out as basically the same colour. Normally i take this mesh from cloud compare and put it into Paraview to do the final colour adjustments, but when i do this in paraview the same is happening. There is very little colour difference between the highs and lows, because for some reason it thinks they are almost the same? This problem has just sort of appeared out of nowhere. I was using the exact same procedure previously and it was working fine. I was getting nice colour variation across the topography. But now there is some kind of error happening in cloud compare that is making the procedure fail. I have tried to change the size of the mesh to see if maybe it was too small, or too big, but size seems to have no effect. Weirdly, it is happening on only certain meshes as well. Others are still working fine. But all meshes were created the same way in Meshlab so i don't know why it is being selective and only working properly for some. There is definitely a good amount of height difference in the mesh for colour difference to register, it just isn't. Can anyone offer a solution or specify a setting that perhaps needs to be changed? Changing the roles (mesh as the reference, or dip as the reference) does not fix it. I'm starting to go a bit crazy over this. Any help is appreciated.

Cheers,
Nathan

P.S i was going to attach images of two meshes to show how one is working but the other isn't, although these are on my computer and i can't see how to directly upload files? Only image URLs

[daniel]

Is it only an issue with the dynamic color scale? Have you tried to set an 'absolute' color scale?
https://www.cloudcompare.org/doc/wiki/i ... es_Manager

Otherwise don't hesitate to send me a sample mesh (and plane if necessary) to admin [at] cloudcompare.org

[nenrique]

Thanks for the reply Daniel. I tried setting an absolute colour scale but the outcome wasn't really what i wanted either. I'll email you the .ply i'm working with, and also a couple examples of what i am trying to achieve. Thank you for the offer of assistance!

[daniel]

Ok the issue was due to the fact the mesh had unused (and therefore invisible) vertices that were much farther than the plane and which were injecting big negative distances and changing drastically the scalar field relative color scale.

Changing the minimum saturation value or setting an absolute color scale (with a lower range) fixes the issue. Another solution is to segment out these unused vertices.