Average point spacing

[hrvoje.lukacic]

Hello everyone,

I have a question regarding calculating average point spacing in CloudComapre. I have to determine average point spacing in 1 cm2 for the purpose of validating the quality of PC. I calculated point surface density with an r=0,01 and got the mean scalar field value of for example of 25441 using this function (https://www.cloudcompare.org/doc/wiki/i ... le=Density) . How do I turn that number into points/cm2 .... for example, I looking for a result like 5points/cm2?

Thank you all in advance and happy holidays!

[daniel]

Hi,

If you chose 'Surface density', and if your cloud units are in meters, then R = 0.01 should correspond to a surface of S = Pi.R^2 = 3.14 * (0.01 ^2) m^2. So 25441 is the number of points divided by S. Which means it's the number of points per m^2. You should simply divide this result by 100^2 to get the number of points per cm^2 (~ 2.5).

Another way to compute this, especially if you have an airborne lidar cloud, is to use the Rasterize tool (https://www.cloudcompare.org/doc/wiki/i ... =Rasterize). Set the grid step to 0.01, project the points inside, and then output the resulting grid as a cloud with the 'cell population' statistics (lower left corner). The 'Per-cell population' scalar field will directly give you the number of points per cm^2.

[hrvoje.lukacic]

Thank you very much for your answer, especially about rasterize tool, it will be very useful in the future.