3D Landscaping & Rendering.
Bryce was made by MetaCreations, changed to Viewpoint, and the product was then taken over by Corel. In 2004 the software was sold again, to DAZ 3D.
This file type is a library of objects for use in MetaCreations/Corel/DAZ Bryce 3D or Bryce 4.
About exporting OBP to OBJ: Bryce 5.5 can only export limited itesm (terrains, rocks, symmetrical lattices, and imported meshes). Go to the Edit window and export from there. Bryce 6 can export those plus primitives/boolean groups if and only if, every primitive has either a positive, negative, or intersecting property. Select File | Export Object to get the OBJ file.