There's probably a painfully simple answer to this, but I've been struggling to figure out how to do it.

I want to create a displacement map over part of a figure, and standard bump over the rest (the alternative would be to be able to assign different displacement levels to different areas).  The different areas do not align with the regular material areas of the figure. Is there a way to do this by assigning a node mask to the displacement channel? Or is there another way to do this. 

Does this make any sense?

I'm using Poser7 SR3.

Any suggestions appreciated.

Is this what you need?
http://www.philc.net/tutorial8.php

 Thanks for replying and the link, Phil. That's a useful tutorial!
I don't think that's quite going to work. If I understand that example, it shows the same displacement level across the entire material zone (6.0), even though there are two images mapped. What I'm trying to do is assign different displacement levels to different areas within the same material zone (ideally, one area would be displaced and the other just bump mapped)., and was wondering if that's possible with a mask.

Going out on a limb here - waiting for BB to come along and give you a more definitive answer:

Displacement (like bump) uses luminance values to define how much or how little displacement occurs. So, I would consider making a mask that has grey -- IColor(127, 127, 127)?? -- as zero point (no positive or negative displacement) where you don't want displacement at all to superimpose over your existing map ... you can do this in the paint programme of your choice.

Did I learn this correctly?? Anyone?

No, Phil's way is how you do it.  If you look at it, you'll note that the black and white face mask is plugged into a blender node, which combines two different displacement maps: the grayscale one for the face, and one for the bricks (you just don't see the brick one as an image, just the settings on the Brick_2 node).  The mask is making sure the displacement for the face only appears on the face, and the one for the bricks on the bricks.

Here's a more useful example for what I imagine you're looking at: this one only uses bump maps, but the principle is exactly the same.  If you look at what I highlighted in red, you'll see that going into the bump setting is a blender that combines the face bump map with something else: in this case, I didn't plug anything into the other part and just left it white, but I could have plugged something in.  The black and white mask plugged into that node makes the skin bump only happen on the part of the face where I want human looking skin, and a raised, smooth surface otherwise.

If I plugged it into the displacement node, it would have worked just as well there.

Here's a way to set up different amounts of displacement using the blender node.  The math nodes are used to control the amount of displacement.

If none of the masking suggestions work, a quick fix would be to simply create the displacement map up to the point you want it to be. and export that. Then, create a bump map and export that. Assuming you're doing this in an app that supports layers, you should be able to get just the info you want per map. It'll be two maps but it'll be two maps that get the job done. Just a thought.

Slightly OT, but a reminder to RV: Poser uses colour value (0,0,0) for zero displacement, not (127,127,127). Displacement maps with a grey base value for zero must have that value subtracted from them to give correct positive and negative displacement data.

As far as I have been able to determine, whereas Poser uses absolute map data for displacement, it uses differential map data for bump. A uniform map of any shade -- black or white or anything in between -- when plugged into the bump channel had no effect on the surface normals, since it contained no differential data. Therefore it is not necessary to offset the zero value of a bump map in the same way as it is for a displacement map.

Corrections / confirmations welcomed, as always.

Uhh, displacement also works on differentials. If you put a uniform gray into displacement you will not see any small variations, although the whole surface will move uniformly.

Bump produces the identical changes in normal as displacement does, but only displacement produces changes in position as well. The bump mapping is calculating the effect of doing the displacement, without actually doing it.

As a result, you can get artifacts in bump just like you can get in displacement, when two nearby surfaces move towards each other and actually cross over, even though bump doesn't actually move anything.

See this post (and the next one on page 2) for a demonstration of bump artifacts caused by not doing the subtraction offset to neutral 0.

http://www.renderosity.com/mod/forumpro/showthread.php?message_id=3363289&ebot_calc_page#message_3363289

Thank you, bb.