I need to use Bryce4 to visualize actual landscapes. As Bryce uses a grayscale gradient
image to indicate the degree of elevation, I
need to convert map images (where contour lines indicate elevation) into grayscale gradient images.

The problem is that the gradient tool in Photoshop
(at least in Photoshop5) cannot handle situations
where the contour lines are not simple (straight
lines or perfect circles) but twist and turn, and
the distance between the two contours is not
uniform (i.e. the gap width varies).

Does anyone know
1) how to do this with Photoshop5?
2) is there a plug-in that does this? (with
my limited knowledge this sounds like a
morphing excercise)
3) is there a program (any) that does this?

Any help is received with deepest gratitude!