complex cloud 2 mesh

[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.

[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?

[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]

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.

[kro_pa]

Thank you. 'Orient normals' options are not active, they are grey... ?

[daniel]

Have you selected the cloud with normals?

[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]

Sadly, LAS files don't store normals. You have to use either CloudCompare's BIN format, or the more generic PLY format.

[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]

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