ZBrushCentral

displacement hint

ZBrush Usage Questions
#1

Hi,
i spent a week trying to make a displacement map to use with maxwell. Everything works perfect with AUV and texture and normal map, just the displacement map simply does not want to function correctly. Than, i discover that, the GRAY value in the map witch should be 50% (128) as stated in manual, it simply isn’t. It’s 149. So, now the displacement works perfect.

so, for all of you frustrated with displacement maps not working in 3.1, check the grey value in your map in photoshop. just a hint.

#2

What’s happening is that when you export the map from ZBrush, 50% gray IS the midpoint value. Unfortunately, you have automatic color adjustments turned on in Photoshop. So when you load the map, Photoshop immediately corrects the colors and thinks it’s being helpful. Suddenly, the midpoint is something else – and will be different for every single map.

#3

I have my color management turned off in photoshop CS3. and the thing is that, after i changed my offset in maxwell from 0.500 to 0.584 (which is 149/255) suddenly, the displacement map wich was not working for a week is now working perfectly. Why, i render my displacement in maxwell render and maxwell does not have a color management so …also i tryied to use the displacement map prior to open it in photoshop. if what u say is right it should’ve worked from the very beginning.

strangely enough, in photoshop, if u sample in grayscale value u get 50% K wich is what fooled me in first place when i was testing the map, becouse i thought well the midpoint is allright, there must be something else… so i started trying different displacement settings and reading tones of threads on displacement and watching countless tutorials. and then, after a week i changed the colour sample in photoshop to RGB and there it was 149. changed the offset in everything is ok.

this has nothing to do with photosop becouse i just checked the map, i didn’t changed it or save it. so it goes from zbrush to maxwell straight. maxwell has also 0.500 offset so i should’ev worked. i didn’t until i adjusted the offset in maxell to 0.584 wich is 149/255. so, again something is wrong in zbrush xporting the greyvalue.

#4

I can confirm this.

I have a model I’m rendering in Maxwell 1.7. If I export a displacement form ZBrush with the midpoint set to .5 and use that displacement in Maxwell with an offset of .5 as well, the displacement will not work correctly. My model actually grows in size, which means, the gray value is lighter than 50%.

If I open that displacement in Photoshop with grayscale color management turned off I see that my mid gray color is actually 73% gray. I don’t know why mine is different than mariot’s, but it is not 50% gray.

If I set my offset in Maxwell to .73 my displacement renders correctly without the model ballooning.

There definitely is something wrong with how ZBrush determines the gray color when Mid is set to .5. Or, there is a setting in ZBrush that is causing this that I am not aware of.

I am using Zbrush 3.12B on a MacBook Pro (Unibody).