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Author Topic: Mesh generation is a problem  (Read 4585 times)

Ingsayyad

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Mesh generation is a problem
« on: May 04, 2015, 03:00:52 PM »
I'm trying to generate mesh from >200 million points. After 5% there is no progress. The clocks are running.
I tried high, middle, low settings. Every time I started my computer to  empty the temps etc.
 Attached please find image.

Arie

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Re: Mesh generation is a problem
« Reply #1 on: May 04, 2015, 03:53:06 PM »
Hi Ingsayyad,
meshing more than 200 Million points with Agisoft will require massive amounts of memory, since afaik the implemenation of Agisofts meshing algorithm meshes all points and then decimates the polygon count.

I would recommend to export the pointcloud and do the meshing in cloudcompare (awesome opensource software). Either use a low octree-depth when using the poisson reconstruction or decimate the pointcloud beforehand. And just reimport the mesh to Agisoft for texturing / referencing etc.

Cheers.

Ingsayyad

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Re: Mesh generation is a problem
« Reply #2 on: May 04, 2015, 04:16:31 PM »
Hi,
 I never have luck to mesh in CC. How can I do it.
What should be steps in this typical case.

Arie

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Re: Mesh generation is a problem
« Reply #3 on: May 04, 2015, 04:21:02 PM »
I would recommend to take a look at the wiki from cloudcompare, the poisson plugin is described there. I'd paste a link, but I'm not sure if that would violate forum rules.

Most important for getting it to work is that the points are exported with normals. After that it is straight forward, you can get a deeper explanation of the parameters on Michael Kazhdan website (link is also on CCs wiki).
Cheers.


igor73

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Re: Mesh generation is a problem
« Reply #4 on: May 06, 2015, 02:02:10 AM »
Interesting, never herd of cloud compare.  How much denser point clouds are you able to process?  Is it faster than Agisoft?  Quality compared to Agisoft and are there good hole filling options? 

To the OP.  If you run out of RAM your only option is to re process the dens cloud at lower setting or split the dense cloud up in chunks before meshing.  For larger projects  400 plus images medium dens cloud setting is often more than enough using 20+ mpix DSLR images. 

bigben

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Re: Mesh generation is a problem
« Reply #5 on: May 06, 2015, 10:07:00 AM »
I'm testing that out. The default settings are quite low so you may need to experiment there.  I really like the colour map of point density on the surface. Makes for a useful gradual selection of faces, especially useful for trimming the edges and also for visualising where more images may be needed.

Arie

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Re: Mesh generation is a problem
« Reply #6 on: May 06, 2015, 12:33:15 PM »
Cloudcompare can handle quite alot of points. Only make sure to deactivate normals in the Properties window on the left. When I load + 100 Million points, I usually minimize the viewport window, uncheck the normals and then maximize again- It's just so that shading is deactivated, which slows down the viewport dramatically.

Cloudcompare hasn't really been developed for meshes, rather for working with pointclouds. So there are no hole filling options (switch to meshlab for that). But then again, the poisson reconstruction provides a watertight mesh and the density output is really useful, since you can use that for segmenting the mesh. Areas, which one wants to keep, even though the density isn't that high, can be segmented again and merged back to the main mesh.
Scalarfields in Cloudcompare are really great!