compare 2 point clouds

[yangyuanyuan]

Hi
If I want to compare 2 point Clouds,How to Quantitative analysis the deformation values. and how can I get the direction information(X,Y,Z ).
thank you very much!

yaoyanli

[daniel]

When computing the distance between two points clouds (with the "Tools > Distances > Cloud/Cloud Dist." method), CloudCompare will output for each point of the compared cloud, its distance to the nearest point in the other cloud (the reference cloud). In this mode, distances are always absolute (positive) as we don't have a 'side' information contrarily to the case where the reference is a mesh.

You can check the 'split X, Y and Z components' check box to get the corresponding distance along the X, Y and Z dimensions (signed this time).

All these results are saved as 'scalar fields' (i.e. one value per point). You can save these scalar values along with the points coordinates as an ASCII file (that can be opened afterwards in Excel for instance). You can also apply several processes and show the corresponding histogram directly in CloudCompare.

[yangyuanyuan]

Hi
Now I don't know how to save these scalar values along with the points coordinates as an ASCII file. The other question is what is SF SCale meaning?

[daniel]

Simply select the (compared) point cloud associated to the scalar fields (SF) and save it in ASCII format (with 'File > Save'). The scalar fields will appear as supplementary columns.

The SF scale is simply the predefined color ramp that is currently used to display the scalar values (the synthetic colors of points) as well as the color bar that is displayed next to the cloud when you check the 'Visible' checkbox in the Color Scale section of the cloud properties.