The Netherlands has a long tradition of children’s illustrators who provide atmosphere without limiting children’s imagination. Our goal is to do the same in our animations. Therefore, the visual art style of the film, which we developed after extensive experimentation, was made for RenderMan rendering software in co-operation with LollipopShaders from Vancouver, Canada. The style was inspired by a number of Dutch illustrators.
-- Ernst Janssen Groesbeek, owner 9to3 Animation Studios
1) Sample “curvature”, where the surface normal of the geometry is evaluated to see how much it changes over a certain patchWe found that these techniques worked well in certain cases, but weren’t providing enough information of certain parts of geometry to creates drawn lines around all features of the geometry, so we developed a few more techniques for edge detection which ultimately provided regions to draw lines in.
2) “facing ratio” which gets us an outline around the edges that are facing away from the camera (typically used for fake lighting and a velvet look), but is camera dependent.