Meshing opportunities

Deformation Analysis Software for 3D Point Cloud Data eg CloudCompare
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StuEv
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Meshing opportunities

Post by StuEv »

Hey guys,

I have a question:

I use 3DReshaper for deformation analysis and i am searching for an option to ignore Gaps when meshing ( for example gaps betweens each stone on a stone wall). In my mind i think of a towell thrown over objects with large/little gaps to get a smoother surface.

I wanna do that because laserscanners do not scan properly on edges and it has influences of the result when comparing two meshes for deformation analysis.

Can anyone help me?
I am also plain for other suggestions/software

StuEv

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Re: Meshing opportunities

Post by kpob46 »

Only thing I could think of is when your picking your options for creating a mesh that you select "Try to keep only the external border". Then once the mesh is created, use the "Regular smoothing" option to smooth out the polygons to your desired level.

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Re: Meshing opportunities

Post by gilles_3DR »

Hi Julian,
from what you describe, I'm not sure I understand what you want to do.
Could you add some pictures of the mesh you have and the areas where you would like to improve it?

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Re: Meshing opportunities

Post by WWilford »

I know that in Geomagic when you are creating the mesh there are options for how many holes to allow in the mesh. Increasing this number may create the effect you are looking for if 3DReshaper has this capability.

There are many other factors to consider starting with your data collection, registration, filtering, etc. which are going to be just as important to your results.

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Re: Meshing opportunities

Post by StuEv »

thanks of your suggestions yet!

To visualize i made some screenshots and edited the last one with paint.The stone wall to which i refer is has 350million points. i thinned it out to 116million points with 2mm space between each point.
i exported this file to *.pts to import it in 3d reshaper.
3DReshaper struggles importing the file because of the point cloud size. i think i have to thin it out more but i am carefull because i want a detailed modell because of the deformation analysis.
Here is the modelling idea i have described above and what i am looking for:

stone wall
Wall1.png
close view
wall2.png
desired modelling option/tool: "towell effect" for closing gaps between stones
wall3.png
Thank you StuEv
You do not have the required permissions to view the files attached to this post.

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Re: Meshing opportunities

Post by WWilford »

I am assuming that this is a dry laid masonry wall (no mortar in the joints).

Since the scanner is capturing some data from the tops and bottoms of the stones in varying degrees depending upon the capture angle it will be difficult to eliminate the joints of the stone automatically in an accurate way. Stray points on the edges will make it more difficult.

If the goal is to monitor deviation of individual stones photogrammetry could be an option.

For a deviation analysis on the entire wall you might consider the opposite approach. Filter the data to eliminate stray points/noise, mesh, reduce spikes, fill holes. It could possibly give you repeatable results, I have never really tried. It could be difficult the certify any results.

For any deviation analysis your coordinates need to be set to a good control to accurately compare the data from multiple capture times.

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Re: Meshing opportunities

Post by max72 »

If you accept to subsample with a point to point distance bigger than the gap, the rasterize function in cloud compare would be a possible approach.
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Re: Meshing opportunities

Post by gilles_3DR »

So, if I understand correctly, what you want is to remove the points which are behind the red areas in your last picture and just make a surface on the points which are on the front of the stones.
For now, I can see 2 options in 3DReshaper:
  1. Use the "ground extractor" tool from the Surveying menu (sounds like the most straightforward proposal! - you'll have to create a local coordinate system so that Z becomes e your wall direction)
  2. Use a filter to remove the points in the gaps before meshing them. To do so, I would suggest 1/ the "Separate with object" tool in the Cloud menu. The object I would suggest to use would be a plane parallel to the wall. In this tool, the right option is "Separate using object orientation": it will compare the local normal calculated on the surface of the cloud for each point and compare this direction to the plane. The points which normal angle is greater than a threshold will be removed. The points going from the stones to the wall should be removed. As for the points in the back of the gaps, I would then recommend the tool "Filter/Explode" in the cloud menu (Explode by distance option) as the points in the back of the gaps should now be at a given distance of the stones
What I would anyhow recommend would be to test these approaches on a smaller set of data first.
Then, I see 2 options again:
  1. either you apply the same approach to all your points at once
  2. or, you apply it to part of the points individually (first, to the lower part of the wall, then to the middle part..) and then merge all these meshes together
Let us know how it goes!

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Re: Meshing opportunities

Post by StuEv »

great help from al of you!!! i will test your suggestions in 3dreshaper!

@gilles_3dreshaper:

great recommendation but i have a few questions:

1. Question: i deleted unwanted points in cyclone to have only the wall left to be exported. Then i thinned out the point cloud to have an homogenized gris of 2mm. Now the ModelSpace in Cyclone has 116 Million points.
I exported the point cloud to *.pts and imported it to 3DReshaper but it always crashes.
What shall I do with the large point cloud to import it properly in 3DReshaper? split it in several parts? export to other file format?

2. Question: I got a student license for 3DReshaper and i cant use the "Surveying" tools like ground extractor :(. Is it possible to get another license to get the full usage of 3DReshaper? I am doing this project for my Bachelor degree.

Thank you so much, all of you!!!

thanks Stuev

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Re: Meshing opportunities

Post by gilles_3DR »

1. Hmm, crash is not normal at all. I (and other users) load very often bigger point clouds without issue. What are your computer specs? Please have a look here about the computer spec we recommend.
In order to test if you have issues because of the number of points, please load a smaller cloud and test the workflow. It could be that the license you have is wrong...

2. In order to get a full test license, do not hesitate to request a temporary license to [email protected] !

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