You Know What's Easier? Practical Effects!

Before we begin, he forgot a button. Moving on, the science is a combination of the physics of the lights bouncing off of everything and computer science; which is primarily the coding of the real life light physics into an algorithm for rendering the the scene's lighting. The Math is what a computer does best, and the base for most computer code. It takes form in geometry, coordinates, vector, and matricies.

Rasterization is when light rays are traced from the object to a single point (the camera) While Ray casting is a ray from the camera to the object.

The first problem with rasterization was that it failed at depth. The objects were layered based on when they made rather than their position in 3d space, with required a Z buffer to fix. Ray tracing solved this automatically only acknowledging what the camera beam first hits. Another problem was shadows. This was solved by drawing a secondary ray after contact is made from the camera rat, redirected to the light, based the lightness on interference with the ray. Another problem was reflections. This is solved by having the secondary rays mentioned before targeting other objects and splitting further.

 Direct lighting is light directly from a source, while indirect light is the light that bounces of stuff. Since light naturally bounces off everything, it is more realistic to have indirect light in the scene while it is less dramatic. 

The problem was over come when James Kajiya calculated the equation of light based on physics. However it was complicated and needed lots of computer power and time.

Moore's law is that the number of transistors in a circuit doubles every 2 years, ie computers are getting way more powerful all the time. While Blinn's law (is it the same Blinn that made the Blinn texture in Maya?) states that rendering time is constant, because the more powerful the machine, the more we do with it.

CGI is far in a way different from other art forms. Primarily due to other forms being physical in some way or another, with CGI is entirely math. Boring and tedious to make, but unique to no end. An overuse of CGI is lazy on part of the Director, not the animator