Triangulate 2D:
- Adds topology to the input points (Delaunay Triangulation).
- Linearly interpolates, bounded by the input's convex hull.

Point Cloud Surface:
- Creates new points and topology.
- Solves on the bounding cube.
- Uses smoother interpolation, with closed or open boundary conditions.
- Adaptive; uses more polygons in areas with higher point densities.
- Requires input points to have properly oriented normals.

Since your dataset is 2.5D by the sounds of it, you'd be better suited using the Triangulate 2D SOP, with Restore Original Point Positions toggled on. The Point Cloud Surface SOP is better for 3D scans.

Hi Ludvík, would you be able to share an example of your setup?

The Point Cloud Iso SOP constructs a mesh from a point cloud with normal vectors. More details are in this tutorial: https://www.sidefx.com/tutorials/surfacing-lidar/ [www.sidefx.com]

This is an area where we'd like to improve our tools. Feel free to leave some feedback here.

EDIT:
The newer Point Cloud Surface SOP is recommended for meshing scanned point clouds.

Hi Paul, I'm unable to reproduce this with files containing spaces. Which version of Houdini are you using?

Also have you double checked the geometry spreadsheet, centered the viewport, or moved the geometry to the origin? Your lidar data could be far from the origin.