Using Displacement we can add geometric surface details, those ones that are difficult or impractical to build and work on in the 3D scene. Displacement shaders move vertices in render time based on parameters you can define in shader. These can be as complex as shaping and forming an entire object to simple things like bumps.
Here is an article I wrote in 2006 about True Displacement for Pixar Renderman/Maya.
It’s interesting to know that it is not yet very practical to make a whole city using displacement. As Prof. Eric Hanson has mentioned at USC DADA VFX and Visualization seminar on Sep 5th, they actually had to have the whole New York city modeled by modelers and not some smart coding or displacement:
It seems that Mental Ray is also able to do some nice displacement job. I'll try to post some displacement results with mental Ray soon.
2 comments:
I just talked to Eric Hanson about what he has done in the Movie the Day After Tomorrow and it apparently displacement was used in many parts of the city. There is a very interesting method that they have used:
They model a building by scanning it using a very precise laser scanner. This way they have a very detailed model of the building including some unnecessary details. For example if there are some fine sculptures in some parts of the buildings, the 3D model of those parts might be more heavier than the whole building itself. In the next step they use Pixar Renderman to get a grayscale height map out of some orthographic views of the buildings. In the last step they use these maps and project them on different faces of simple objects like cubes to have the final building almost like if it was really modeled. They save lots of time and energy during this process. Moreover, the rendering time will be much faster than using real 3D models! I should add that this method is not very good in case that a building will be in close-up view.
So again, Displacement is the way to go!
I should note that Maya Fluids Ocean Shader is heavily based on Displacement. Please refer to my post here: http://usc-vfx.blogspot.com/2007/10/displacement-in-ocean-shader.html
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