height_field
// uses image color index as height, extends along X-Z axes
// from <0 0 0> to <1 1 1>
height_field {
png // the file type to read (tga/pot/pgm/ppm/png/sys)
plasma3.png // the file name to read
// [smooth] // smooth surface normal
// [water_level N] // truncate/clip below N (0.0 ... 1.0)
// texture {...}
// translate VECTOR | rotate VECTOR | scale VECTOR
}