3D Animation School: Rendering Cars with Mental Ray
March 16th, 2009 Posted in 3D Animation School
When watching a car commercial one can safely assume that cg cars will be used for many of the shots. Depending of the location different kinds of lighting will be need to be represented, recreating reflections of the surrounding landscape, be it city or countryside also needs to be taken into account.
Mental ray has many different kinds of shaders (shaders determine the surface characteristics of a 3D object) for describing the look of elements in a scene. This semester we have spent 2 classes just on car shaders in mental ray! There are a set of shaders in mental ray called architectural shaders (called mia) that contain many attributes essential for creating a car surface. Although there is already a shader in the mental ray library called appropriately a “car shader” we usually create our own from mia shaders for greater options and flexibility for the look of the car paint.
In order to create the surface look we need it’s necessary to create what we call a “shader tree”, which is composed of a number of shaders, textures and utilities. Shader trees can range from simple to outrageously complex. The car shader is relatively straight forward though understanding how all of the attributes contained within the mia shader work together can be quite an endeavor. It’s not just putting all of the the “nodes” together, but also optimizing them to render in the shortest time possible. Rendering just one frame for a movie can take many hours, and as there are 24 frames per second for a movie and 30 fps for TV, rendering a 5 second shot can take allot of time and money.
Understanding how lighting and shaders work is a big part of creating convincing animation in games, commercials and movies. At the New York Film Academy we take allot of time and effort with the students in this area, ensuring that they graduate with an in depth understanding of mental ray fundamentals, lighting and their importance in the cg pipeline.
Robert Appleton, 3D Animation School Instructor
