Calculation of rock volumina from PointClouds (Meshlab?)

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Tsunami
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Calculation of rock volumina from PointClouds (Meshlab?)

Post by Tsunami »

Dear all!

I am pretty frustrated after numerous failed attempts.
It should be a quite simple task but I am a self-taught newbie, so I still lack many basic skill.

What I did so far:
Registered point cloud in Faro Scene
Exported to CloudCompare, where individual rocks (about 250) have been extracted.
These rocks are irregularly shaped and have (sometimes big) voids, especially on their bottom.
Exported as *.ply to Meshlab

What I want to achieve
Approximate volumina of numerous rocks.
I know due to the lack of points on some parts, volumina will be not super accurate.
This is not that important to me.
A simple as possible and quick approach due to the huge amount of single objects

What I tried:
1. Trying to create a watertight mesh in Meshlab to calculate volume
-> difficult, as I got a lot of bubbles and all rocks need an individual correction, which I failed to do

2. Tried to "compute geometric calculations" in Meshlab
-> I do not get an output for Volumnia, just for the principal axes


So.
Do you know how I could proceed?
I need a simple method, I cannot dive into numerous programs as this is just a small side-project.
But Im geting really frustrated :(

I attached an sample file, so maybe someone could help me out of my misery?
RockSample.zip
Thanks a lot and best wishes!
Frieder
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max72
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Re: Calculation of rock volumina from PointClouds (Meshlab?)

Post by max72 »

I gave it a whirl.
I would start with GOM inspect (free, it takes a little bit to get started).
With Gom Inspect you can mesh the cloud, and the close the holes. For big holes you can create a set of bridges before capping the bottom and some big holes.
You can fix small issues too.
The critical part is choosing hot to close the bottom.
Export as stl. not perfect but quite close..

After that you can export the stl and do a final poisson (it creates a watertight mesh) and calculate the volume. Otherwise heal and create a watertight mesh with meshmixer.
I tried to close the mesh with Rhino and calculate the "poissoned" one and I get about 45.3 m3 with both. The one closed with Meshmixer gives 45.25.

Massimo
ing. Massimo De Marchi - +39 347 32 17 049 - www.studiodemarchi.net
Tsunami
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Re: Calculation of rock volumina from PointClouds (Meshlab?)

Post by Tsunami »

Dear Massimo,

thanks a lot, that looks promising already.

I somehow could calculate the volume of the rock before and got similar values than you did.

I downloaded GOM Inspect, but I am already failing to mesh the point cloud. I cannot find the proper function. :oops:
Can you hint me here please?

As it seems, GOM also offers of calculate the length and orientation of the main 3 axis, right?
That would be the next necessary step after volume calculation.

Thanks a lot and cheers
Frieder
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Re: Calculation of rock volumina from PointClouds (Meshlab?)

Post by max72 »

Gom requires a little bit to get used to. Moreover the main tharget is check the point cloud with a CAD model, and the data it's made for is far less noisy..
I attach some pictures with the workflow I used:
1 - drag and drop the ply, and import as pointcloud
2 - Compute the normals
3 - select the area of interest (in your case select all)
4 - mesh it
5 - close the holes
6 - you can do automatically or interactively
7 - with big holes it's tricky
8 - create bridges to have smaller and more regular holes
9 - Close the new smaller holes interactively
and the export as STL..

Massimo
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Tsunami
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Re: Calculation of rock volumina from PointClouds (Meshlab?)

Post by Tsunami »

Dear Massimo,

thank you so much for your help!

This workflow is simply perfect for me and works like a charm!
Best wishes!
max72
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Re: Calculation of rock volumina from PointClouds (Meshlab?)

Post by max72 »

Great!
Consider I'm a lame user, and gom inspect offers a lot of options.
In case you want to learn more I'm confident you can find training sessions near you hosted by gom itself.
While not made for TLS as you can see it offers some great features.
Cheers,
Massimo
ing. Massimo De Marchi - +39 347 32 17 049 - www.studiodemarchi.net
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