interpolation
v0.1; caminoix; 10.07.2006
v0.2; caminoix; 03.09.2006
download source | binary

interpolation is a pretty well known algorithm the descriptions of which can be easily found on numerous websites. i don't feel there's a great need to merely reproduce here what you can find elsewhere without any trouble.
there are quite a few of methods of interpolating. this plugin currently implements two of them: the linear and the cosine variations. to be honest, their results are very similar on heightmaps, and i certainly wouldn't be able to tell which one was used if were shown a smoothed heightmap. as a matter of fact, i wouldn't be able to tell the difference even if i were shown a map smoothed by the averaging algorithm, still simplier than interpolation.