because 8-bit heightmaps limit you to 256 different heights, which results in jagged slopes on hi-poly terrains.

in MED you get to set the influence of each colour channel on the heightmap (if i remember correctly... i haven't used it in a while). u could have red * 1, green * 256, and blue * 65536.

looking back at your question, you need help in the making, and not the using... in which case my post is useless. sorry. i can't think of how you'd easily make one.

julz