3D Scanned Data (OBJ)

The Umbra command line tool that is included in the SDK package is meant for importing and umbrafying 3D content.

This guide is tailored specifically for scanned 3D data originating from laser scans or photogrammetry that have been converted into OBJ-files rather than kept as raw point clouds.

A good example of such a situation is when you convert a dense point cloud generated by a photogrammetry software into OBJ-files. The 3rd party software used specifically in this case has been RealityCapture.

How to umbrafy 3D scanned data set

  1. Start by storing your 3D model in OBJ file format. There is an upper limit of 53 million triangles per .obj file, so large 3D models should be split into smaller individual .obj files. It is possible to have the files reside in a folder hierarchy as long as they all share the same root folder.

Good Practices:

  • Store your large scene in multiple smaller .objs (smaller being some gigabytes per file), making sure the maximum triangle count per .obj is less than 53 million
  • If your OBJ input is in world coordinate space, you should first translate it to a local origin before umbrafying it
  • Remember to put inputs inside quotes in case they contain spaces (i.e. –scene-name “Helsinki 3D data set”

Find the right feature-size parameter for your 3D data.

  1. Download SDK package from the Downloads section of Umbra 4 portal.
  2. Run umbra.exe in your command line prompt with following parameters. Example usage is provided at the end of this document