Sculpted Prims: Importing
Currently there is a push to get the client to import models as sculpted prims from a variety of 3d modeling formats.
| • | 3dm | – | Rhino & MoI | VWR-858 |
| • | 3ds | – | 3D Studio Max | VWR-1111 |
| • | obj | – | Wavefront | VWR-1110 |
The main method currently for doing this translation is to use UV mapping cordinants to retrieve positions on the surface of the mesh. There are three hurdles to this.
- UV mappings may be missing or not continuous.
- The objects may be made up of multiple surfaces.
- Distributing the limited LOD appropriately.
- Stitching surfaces together. The UV mapping along the edges may not align.
Current importers & converters get around these problems by ignoring them and only allowing the user to import one surface objects with continuous UV coordinates.
The correct approach to this is to refactor the mesh and UV coordinates into a single surface. To stitch two surfaces together without complex math, the derivatives of the UV coordinates need to match on each side of edge.
my concern here is that there is no one good way to convert an arbitrary mesh to a parametric surface. there are many partial solutions, which when used by hand and in conjunction with each other can do the job - but to automatically handle all OBJ files seems to be an impossible job. i guess i could be wrong - but i'm looking for proof in the pudding. my metric has been "if it can import 90% of the shapes present on turbosquid.com without too much error, then it's ok." --Qarl Linden 16:13, 26 June 2007 (PDT)