Displacement Map Information or tutorials
RKane_1
Posts: 3,037
Is there a good source for info regarding handling Displacement Maps in DAZ Studio?
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Simplest piece of advice is to avoid any that were designed for Poser, you'll recognize them when you see them as they look like transmaps, in DS these cause the mesh to shrink inwards from the normals and cause 3Delight to cough up displacement bound error messages.
Displacement maps are grayscale height maps. (Colour will be interpreted into grayscale based on luminence.) You have a map, min and max settings. A completely black pixel will displace the mesh by the min setting (which might be negative, and in fact DAZ defaults to negative). A value of pure white displaces by the max setting. Values in between represent a scale between your min and max settings. With the default of min -.1 and max .1, a gray pixel of 128 would be 0 displacement as it's half-way between the min and the max, so 0.
Displacement maps are thus similar to bump maps, in that they are both height maps that range from a min to max value specified as additional parameters of the surface, except that bump maps only affect the shading when ray intersection is calculated with the surface. A displacement map causes the rendering engine to alter the mesh. Because it alters the mesh, a surface with displacement will cast true shadows, while a surface with a bump map does not.
For Bejaymac: how does Poser handle displacement maps that makes it different with DAZ? Does Poser default min to 0 instead of a negative displacement, like DAZ does? I know LuxRender handles displacement maps the same way DAZ/3Delight do.
Yes, Poser, at least the older versions, handles them differently.
Does the newer version of Poser handle them the same way DAZ Studio does now?
@ cwichura: Wow! Did you copy that from a wiki on it or just rattle that off from your head? THANKS! That is a great start!
I have ZBrush and I am trying to find out how to make a displacement map in that and somehow have it transfer over to DAZ but tutorials for it are few and far between. I keep worrying about modifying the mesh and then it not transporting over. *sigh*
For those who HAVE done a displacement map for use in DAZ, how did you do it? What software did you use and what was your process?
Pm me and I'll show you. Its very easy
Still hoping for someone to explain how Poser handles displacement maps vs the rest of the 3D world. Thanks! :)
Poser differs mainly in that it doesn't have min and max values - by default black is zero displacement. Yoyu can make DS behave in the saem way by setting the Min (or sometimes the Max) to 0. Poser can be made to behave like DS, and most other applications that use displacement, by using a math node to adjust the value (subtract .5 for the default DS behaviour).
What is Poser's equivalent for Max then? The same .1 that DAZ defaults to? Or something else?
I can't recall what Poser uses to determine how great the maximum displacement is - it used to be a size-dependent factor, based on the model, but I'm not sure that's still true. Still, that's a question of fine-tuning the values rather than an actual difference in the way the maps are used.
A quick and dirty to show what I mean, create a plane and plug the first image into displacement, set the strength to 200% (makes it easier to see) and using richard's suggestion turn min disp to 0, and then render.
You will notice that the dark gray curve doesn't show in the render, that is because you told 3Delight to ignore everything between RGB 0,0,0 and RGB 127,127,127 and only to use RGB 129,129,129 to RGB 255,255,255. Not much use when the displacement map uses those colors in the design.
Now plug the second image into the plane and set the min disp to it's default of -0.1 and render, that is how a displacement map should look and work for 3Delight, that is also how a bump map should be as well, none of this gray scaling a diffuse map, inverting it or otherwise.
Sadly until that lot (points at DAZ and the venders) get their heads out of their Poser asses we will continue to get this 2nd & 3rd rate garbage to work with
I have to disagree, the dark curve is showing if you make the displacement strong enough - in this case, I've set the strength to 100%, the Min to 0 and the Max to 30.
Thank you Richard for showing just how useless Poser displacement maps really are in DS, you see that dark curve is meant to sink into the mesh and not rise out of it. ROFL
So you are saying Poser takes a displacement map and splits it in half at the K=128 point, and the lower half is used for negative displacement, but it's still shown in 'positive' direction in the map (e.g., two 'positive' maps stacked together) whereas everything else (DAZ, LuxRender, etc.) treats the map as a single gradiant from min to max?
If you want the curve to sink in relative to the rest of the map then it has to be the black part of the map, or darker than other parts if you don't mind wasting some of the tonal range, with the Min/Max values set appropriately in DS or a suitable offset applied in Poser via a Math node. The map you posted is behaving just as it should, and can be used with the right settings in both Poser and DS to rpoduce the same result.
I'm not sure what is being said, but that isn't so. Poser has only a single parameter in its root node, equivalent to strength I suppose, and a raw map is treated as 0 to 1. By using a math node you can offset that - subtract .5 and it will give -.5 to .5, double it and subtract 1 and you get -1 to 1 as in DS with Min = -Max. Both Poser and DS treat the spread of grey values as a continuous gradient, the differences are in how you adjust the end points of the gradient and what the default values are.
http://www.4colorgrafix.net/blog/2009/10/01/from-poser-to-dazstudio-displacement-maps/
http://www.calida3d.com/tutorials2c.shtml
Thanks for all the info, guys!
So what is a displacement value in DAZ|Studio equivalent to? If I have a b/w map, and I set the min. diplacement value to "0," what are the values for "displacement strength" and "max. displacement" doing? "1.0" tells me nothing nor does "100%"; I want to know the physical measurement of the displacement - if I want 1/8", or 1/2", or 3 mm, how do I get any of those?
The minimum displacement is the value applied to black pixels, in cm. The maximum displacement is the value applied to white pixels, in cm. The strength modifies that - if it's 50% then the values (in cm) will be halved. So in your case, black pixels on the map will cause no movement and white will move the surface out by 1cm.
This information is very useful, but I have one more question to add. Is medium gray always "no displacement," or is it the midpoint of the maximum and minimum values? E.g., if minimum is set to 0 and maximum set to 1, would medium gray in the map give you 0 (no displacement) or 0.5 (the midpoint of the min and max values)?