terrain data - TIN

[Francis]

Have anyone use polyworks to load terrain data like lidar (las) or any DTM to construct NURBS?
Any suggestion to do a good job or just to know your idea about that? ideal file format...

[prehistory]

Hi Francis,

PolyWorks doesn't currently import the .las format, but I think they are working on adding that functionality.  However, you should be able to convert your .las file to .xyz or some other simple text file format consisting of x y z and intensity, or similar.  If it were me, I would import the file as a point cloud into IMEdit, then wrap the point cloud to make a mesh, then create your NURBs patches on top of the mesh.

That would be File > Import Objects > Point Cloud from Text File
Make sure to set your Template to reflect the format of your text file.  You can add templates or pick predefined ones by clicking Templates in the import interface.  Once the point cloud is in, use the Mesh tool, Edit > Point Cloud > Mesh to make a polygonal skin.  Set the Max edge length larger than your lidar point spacing, maybe 3-5x the point spacing.  Set Curvature Based Subsampling to reflect the % of points you want to keep in the mesh, reducing unnecessary points in smooth areas.  Set the Reduce Noise parameter to smooth out small imperfections.  You can do this same process in IMInspect, but NURBing has to be done in IMEdit. If your mesh looks crazy, you may benefit from first subsampling your point cloud (Edit > Point Cloud > Subsample) to get more even spacing.

Once you have your polygonal model, you can ignore the imported point cloud.  I would clean up the mesh a little using, in order:  Optimize Mesh, Click and Fill Holes, Smooth Vertices (Interactive), and Optimize Mesh again.  Then lay out your curves and make a NURBs patch.  Good luck and happy NURBing!

[Francis]

Thanks :)