Modeling and Exporting
There are many great tutorials, books, and references for different modeling packages already. Here we'll just cover some basic tips for using Maya to make models for the CAVE.
- Only Polygons
Maya supports several types of geometry - polygons, NURBS, and Subdivision Surfaces. In the image above, the three objects on the left are polygons, while the two on the right are NURBS. Ygdrasil, like most realtime 3D engines, only supports polygons because that's how all 3D graphics are drawn by the computer. If you use NURBS in a scene, Ygdrasil will just ignore them. You can model with NURBS, just convert them to Polygons (Modify->Convert->NURBS to Polygons) before exporting. Same with Sub-D's.
- Low-poly Models are Best
When rendering CG animations, your geometry can be as complex as you want - just add more machines to your renderfarm and set it going overnight. For realtime, though, remember that the whole scene has to be redrawn every frame! ideally you want frame rates well above 30fps - 60 to 100fps are a good range to shoot for. Below 20fps the illusion of motion starts to degrade and movement becomes noticeably jerky. This Lag is a serious detriment in VR, because it not only creates a jerky image but breaks the sense of continuity between the viewer's movement and what they see, contributing heavily to VR-sickness.
- Start simple, add detail only where you need it
It's not easy to simplify a complex model. keep your model simple, and just add detail where you need it by extruding, splitting polygons, subdividing, etc.
- Use textures to provide detail
Instead of modeling fine detail on a surface, use textures on simple polygon surfaces to give the impression of detail.
(c) Ben Chang