As I understand it, Unity uses PhysX. So, do the Heightfields used in Unity use the same type of Heighfields in PhysX? If so, what kind of interpolation do they use? I made my own Heightfield implementation which uses bilinear interpolation, but unfortunately I am unable to determine which type of interpolation Unity uses for its terrain. Thanks.

-T

I would assume either bilinear, or actually using the triangles for collisions. The latter is a good idea if you want visuals to match exactly (as in objects never floating slightly above or slightly below the visible terrain, which you can get if you do collisions separately from the visible geometry).

Yeah, but that's an assumption. I need a definitive answer. Can anyone give me one?

i dunno the sdk but post a pic of the interp..

"one up" is s-curve, aka "cosine"
d = d * d * (3 - d - d);

bicubic is where one may start to have difficulty determining alignment of axes. as far as i know :) i doubt it's used tho, 2nd order not fast.