complex cloud 2 mesh

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kro_pa
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Joined: Tue Mar 01, 2016 9:52 pm

complex cloud 2 mesh

Post by kro_pa »

Hello,
How to do mesh from *.las - big and complex point cloud? Poincloud is from cave - very complex wall's relief, c.a 80 mln points.
1) Cloud have normals (by triangulation), 2) PSR on lv 8 split cave for different parts (screen in attch.), 3) PSR on on level 17 is a one big green buble :-), 4) PSR on higher levels was never made - reconstruction is always failed.
What do I wrong? Thanks for advice in advance.
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daniel
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Re: complex cloud 2 mesh

Post by daniel »

Level 17 for PSR is already gigantic, so it's not a surprise that it fails above this level ;)

But the result is definitely not what I would have expected! Are the normals properly oriented? They seem to be a bit randomly oriented. How did you compute them exactly?
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kro_pa
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Joined: Tue Mar 01, 2016 9:52 pm

Re: complex cloud 2 mesh

Post by kro_pa »

Thank you for reply.
I have just made Edit/normals/compute. Then I've choose 'triangulation' , rest I have left as default.
daniel
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Re: complex cloud 2 mesh

Post by daniel »

Ah ok, then it's probably the cause of the issue here. Only computing the normals (with triangulation or any other algorithm) won't be sufficient. You need to get well oriented normals (i.e. all normals pointing outside of the surface for instance), which is generally not the case at first as CC can't guess where is the inside and where is the outside. You'll have to play with the 'Edit > Normals > Orient' methods, but it can be very tricky on complex shapes such as the share of your cloud. If you struggle too much, you can send me your cloud, and I'll give it a try.
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kro_pa
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Re: complex cloud 2 mesh

Post by kro_pa »

Thank you. 'Orient normals' options are not active, they are grey... ?
daniel
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Re: complex cloud 2 mesh

Post by daniel »

Have you selected the cloud with normals?
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kro_pa
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Re: complex cloud 2 mesh

Post by kro_pa »

I did :-). After computing normals I have saved cloud as *.las again. Re-saving as *.las saves normals in cloud also or do I have to compute them again?
daniel
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Re: complex cloud 2 mesh

Post by daniel »

Sadly, LAS files don't store normals. You have to use either CloudCompare's BIN format, or the more generic PLY format.
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paddywhells
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Re: complex cloud 2 mesh

Post by paddywhells »

I have a similar issue with a point cloud from within a cave. I'm having trouble orienting Normals effectively. I've tried Z, Barycenter, and spanning tree (knn=6) but get funky results. do you have any suggestions for a long narrow cave? Did a solution come out of this original post that I could use?

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daniel
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Re: complex cloud 2 mesh

Post by daniel »

Do you have a set of points describing the scanner path - in the middle of the cave / tunnels - maybe?
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