I have been having a great time working on the environment mapping chapter. Comparing and contrasting the differences between cube, sphere, and paraboloid environment mapping is an enlightening task and I have a much better understanding after doing it.

One example of what I've learned is how to control the unavoidable 'singularity' inherent to sphere mapping. The singularity is basically positioned on the far side of the virtual reflecting sphere, so you can steer the singularity away from the current view. There are caveats to doing so, like issues with how close geometry can be to the singularity on the far side of the reflective object, but hiding the artifacts is pretty important.

I found it interesting to look at how the artifacts look if you intentionally don't hide them. Here's a sample image of what I'm talking about:



There will be more to come on environment mapping...