Rendering

The semester has ended, but I still want to go back and revise the discussions that I couldn't include in time. Before the discussion of VR technology, we had a class talking about rendering technologies, which I'm not familiar with. Many fellow students from animation background have mentioned it very often, but all I know is that it is a technology that decides the color and light intensity of each pixel from the 3D model to project a 2D image, so that it can be displayed on the screen.

It seems that the computation cost for rendering is very expensive, or there wouldn't be a term called "render farm", and I have heard from fellow students that it takes several hours just to render one frame. They were rendering for an animation project, but this rendering speed is definitely not practical for game industry, where it has to be real time. The first paper that we talked about was a simplification designed for games. The BRDF (Bi-directional Distribution Function) to decide how much light can be seen from different directions was approximated by a sinusoidal function called LTC (Linearly Transformed Cosines). Ubisoft has implemented this method in its product, and the results look satisfying, although there is no shadow. Actually, I didn't really notice that.

There are also many efforts to reduce the rendering computation costs in movie production. One was using sorting method to speed up ray tracing process. Although the concept is very easy, it is surprisingly effective.
We have also looked through some special techniques of rendering scratches, cloth and sand. They all look so impressive. I'd like to look more into it when I have more time.