points per square meter in a point cloud

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chichho2017
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points per square meter in a point cloud

Post by chichho2017 »

Hello everyone,

I'm researching about how to calculate the number of points per square meter in a point cloud. This is possible?

I hope you can help me.
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Re: points per square meter in a point cloud

Post by Jamesrye »

Pretty easy in Cyclone. Make a limit box 1m square, copy the data to a new modelspace - unify, then pick the cloud, right click and choose object info.

Alternatively, export the points from whatever software you use and count the number of lines in textpad. You could do this using RECAP, which is free, though you might need the PRO version for the clip box...

https://forums.autodesk.com/t5/recap-fo ... -p/6868595
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Re: points per square meter in a point cloud

Post by andyevans »

chichho2017 wrote: Tue Jun 19, 2018 4:04 pm Hello everyone,

I'm researching about how to calculate the number of points per square meter in a point cloud. This is possible?

I hope you can help me.
Well, I'll give you an insider heads-up.

The next release of Topcon's MAGNET Collage has a "colour by density" option.

It's coming soon, and I suspect will meet your requirement.

It's coming soon, I'll let you know when it is ready for release.
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Re: points per square meter in a point cloud

Post by VXGrid »

Is this about the complete point cloud or just to take a mean?
If you have a point cloud of a building the density and therefore the amount of points per m² is depending on where you are. In addition I think the amount of points in 3d would make more sense, since the point cloud is 3d as well.
If you like to write something on your own:
Generate boxes (cubes) with the size of 1 m, iterate through the complete cloud and sum the amount of points which fall in certain cubes. Then you have a complete 3d grid with the exact point number per m³
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chichho2017
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Re: points per square meter in a point cloud

Post by chichho2017 »

Jamesrye wrote: Tue Jun 19, 2018 4:25 pm Pretty easy in Cyclone. Make a limit box 1m square, copy the data to a new modelspace - unify, then pick the cloud, right click and choose object info.

Alternatively, export the points from whatever software you use and count the number of lines in textpad. You could do this using RECAP, which is free, though you might need the PRO version for the clip box...

https://forums.autodesk.com/t5/recap-fo ... -p/6868595
thank you very much! I'm going to try that technique. 8-)
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Re: points per square meter in a point cloud

Post by chichho2017 »

andyevans wrote: Tue Jun 19, 2018 6:21 pm
chichho2017 wrote: Tue Jun 19, 2018 4:04 pm Hello everyone,

I'm researching about how to calculate the number of points per square meter in a point cloud. This is possible?

I hope you can help me.
Well, I'll give you an insider heads-up.

The next release of Topcon's MAGNET Collage has a "colour by density" option.

It's coming soon, and I suspect will meet your requirement.

It's coming soon, I'll let you know when it is ready for release.
that would be great! I think this data is very useful to know for planning a 3D modeling with a high LOD
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Re: points per square meter in a point cloud

Post by chichho2017 »

VXGrid wrote: Wed Jun 20, 2018 9:16 am Is this about the complete point cloud or just to take a mean?
If you have a point cloud of a building the density and therefore the amount of points per m² is depending on where you are. In addition I think the amount of points in 3d would make more sense, since the point cloud is 3d as well.
If you like to write something on your own:
Generate boxes (cubes) with the size of 1 m, iterate through the complete cloud and sum the amount of points which fall in certain cubes. Then you have a complete 3d grid with the exact point number per m³
Interesting point of view, at the beginning my interest was to set up an amounth of points per square meter as standard for 3D models with different LOD; :geek: Thank you very much for sharing your information!
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Re: points per square meter in a point cloud

Post by gsisman »

chichho2017 wrote: Wed Jun 20, 2018 2:38 pm
VXGrid wrote: Wed Jun 20, 2018 9:16 am Is this about the complete point cloud or just to take a mean?
If you have a point cloud of a building the density and therefore the amount of points per m² is depending on where you are. In addition I think the amount of points in 3d would make more sense, since the point cloud is 3d as well.
If you like to write something on your own:
Generate boxes (cubes) with the size of 1 m, iterate through the complete cloud and sum the amount of points which fall in certain cubes. Then you have a complete 3d grid with the exact point number per m³
Interesting point of view, at the beginning my interest was to set up an amounth of points per square meter as standard for 3D models with different LOD; :geek: Thank you very much for sharing your information!

As vxgrid said the density per SQUARE meter is based on how far you are from the surface you are reflecting from. Most all scanners have different density of scanner output but in any given "Perfectly reflective closed area" there is the exact same total number of points scanned no matter what size the area is. What changes is the density/spacing of the 3D points. You would need to be careful when calculating that depending on the software. Every software I've tested has a fixed size for a "clipping box" which does not change in relation to your zoom and extends to infinity radiating out from your point of view. A limit box however is 3D and usually is linked to the zoom capability. So extracting a meter square of points in either Method would be different. You would also want to do this in one point cloud from a specified distance. You would come up with a myriad of answers depending if you have overlapping scans hitting the same surface, and they were different distances from that surface, even though the density on the scanner was set the same
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