We introduce Pseudo-Collisions (PC), a numerical and time independent method to reduce the collisions between short fur and the skin of an asset as it deforms during animation. Typically, solving these intersections in a standard workflow would require a lot of time to set up and simulate each strand or their guide curves. With our solution, this can be achieved with a light post-process on top of the applied fur. This is achieved by adjusting the transformation matrix used to place the strands on the animated skin so that its rotation component smoothly lifts the hair where necessary.
The algorithm dynamically adjusts the orientation of the animated strands to reduce the intersections using different pieces of information including the direction of the strands, the placement matrices for each strand on the rest and the animated skin meshes, as well as the change in the surface’s curvature due to the deformation. Pseudo-Collisions was successfully used during the production of Mufasa: The Lion King and the set of parameters made available to the users to modulate the results of the correction is also presented.