Heightmap format?

[kelvin]

In my current project I'm using a height map for an artificial potential field. From this height map I calculate a normal at an arbitrary point (average of the surrounding 8) to get a force vector.

My question is: What is the optimal format for my height map?
I'm currently thinking just an array of floats.
I need at least 16 bits of precision for height.
I want something easily saved and edited, perhaps in a graphics app like photoshop.
Right now, I'm using it purely for calculation and not display; but if possible I'd like to leverage any kind of acceleration I can out of OpenGL.
*note: I don't need to convert the whole map to a normal map, just arbitrary points, so it's not too CPU intensive (I hope).

thoughts?

[Jake]

I use a 16 bit RAW greyscale image for my motorcycle game - my only complaint is that photoshop can't use all its filters on 16 bit images, but it still has enough functionality to work.

[DoG]

Why dont you just use a normal map, if you need the normals anyway?

[kelvin]

I'm generating the height map live.

[arekkusu]

What is your minimum hardware requirement?

[kelvin]

800MHz G4 and a card that will support OpenGL 1.3 (maybe not the 7000)

[arekkusu]

I think you'd better stick to the CPU then.