CloudCompare forum

Hello everyone!

I'm working on my thesis work and I have a problem with Facet plugin. I want to know dip and dip direction values from point cloud of wall of mountain.

My steps are:

1) Insert point cloud in CloudCompare
2)Then in EDIT > NORMALS > COMPUTE. There are two options, I chose "Plane" : Is it right?And "prefered orientation"?
3)Then EDIT > NORMALS > CONVERT TO > DIP/DIP DIRECTION. The software generates a colored map but when I go in PLUGINS > FACET > EXPORT FACETS, the error message comes out "Couldn't find any facetin the current selection". But my cloud is selected on the control bar!

How can I fix the problem?
Thanks for the answers!

Layla244

Hi Layla244,

please allow me to comment on your questions

2) re normal computation - from what you discribe you want to do, choosing "plane" is good. Re preferred orientation - if your rock face is generally facing x, y or z then you could choose accordingly, if you don't know, you can choose "Minimum Spanning Tree" (I think it takes a bit longer). Once the normals are computed, I would turn the normals off (not displayed) by ticking the box in the properties - this is easier on your graphics card when you use large clouds. If you don't want to think too much about the settings, you could use the new plugin "Hough Normals Computation" and just take the settings as they are (might also take a bit longer on larger clouds). Both methods differe a bit, one is using a search radius, the other the set number of neighbours to calculate the normals. Personally, I think their might be a bit of a problem with these normals calculations if your scanned object (rock face) has different sized surfaces that you need to detect within different areas - note that the settings for the normal computation are the same for the entire point cloud. If this is a problem for you, you should first manually cut the cloud in segments with homogeneous surface size and do the normal calculation for each segment with individual settings.

3) re export facets - it sound like you skipped a step - you may need to "Detect planar facets..." first, there is two different methods "Kd" and "Fm". It is quite well explained if you google "cloudcompare facets"

hope this helped

cheers

mat