Displacement map Zbrush 3.5 - fine details lost when exported

[Storm]

Hey,
My problem is, as the title says, that I loose all fine details when I export my displacement map from zbrush, or at least it seems that any other program than zbrush, can’t read the details (zbrush reads all the fine details in the map when I apply the map to a newly imported OBJ).
Some pictures to illustrate:
This is my model rendered in zbrush, at subd 6.
http://www.frederikstorm.dk/images/…ptextured10.jpg

And this is what a friend of mine gets when he tries to apply it to an imported OBJ in max:
http://henrikbclausen.com/kyklop_12_disp.jpg
http://henrikbclausen.com/kyklop_13_disp.jpg
I think the images speaks for themselves.

And just to compare the two maps:
http://www.frederikstorm.dk/test/dispnorm.jpg
This shows even more clearly just how poor the map is.

And this is where it gets really funny, 'cause zbrush apparently have no problem reading the fine details in the map, this is a little test I made in zbrush, where I exported the mesh at subd5, closed zbrush, opened it, and then imported the newly exported obj, and then applied the displacement map:
http://www.frederikstorm.dk/test/te…mapinzbrush.jpg

All the maps used are at 4096*4096

And the “funny” thing is, I get perfect normalmaps, no problem at all, but I must have totally missed some setting when exporting the displacement map, but I have tried for around 4-5 hours playing with the settings, and searching for some help on the web, but no luck.

I really hope some one out there know what we are doing wrong, and how to fix it.

On a total side note, my friend who did the max renderes, would like to know, why the normal map works so good as displacement map, this is the model with normal map applied as displacement map:
http://henrikbclausen.com/kyklop_12.jpg
http://henrikbclausen.com/kyklop_13.jpg
Obviously the shape is not quite right, but its still a lot better than the results with the displacement map applied as displacement map.

[Kerwin]

You probably have captured the fine details in the map since ZB can read them back and display them. So logically, it would follow that the information about displacement is indeed in the 2D map. From this it would follow then that you should probably look at what your settings are in Max.

Things to look at in your Max: shading rate settings (I think this is called Max Subdiv in current Max-Mental Ray setups.) Second, check that your displacement map strength setting is sufficient to bring out the details (Min and Max height I think are the settings.) I’m not sure whether you are using 16-bit or 32-bit displacements, so this may be messing you up. Make sure your Max is correctly configured to support the map-depth you are using. (I remember that some earlier versions of Max cannot read 32-bit displacements, but that was a long time ago.)

Here is a link to Mudbox->Max workflow; the Zbrush would be similar, but the Max parts may be relevant to your setup:
http://www.neilblevins.com/cg_education/mudbox_2010_to_max/mudbox_2010_to_max.htm

-K

[Storm]

Thanks man, really appreciate it, I’ll take a look at it, and post and update

[Storm]

Update,
We’ve been messing around with this for god knows how long, and Kerwin thank you, while it wasn’t 100 % what I was looking for, it helped me get on the right track And we are now a lot closer to solving this mystery.

Okay just to let you guys get in on the progress, I generate a 32bit 3 channel thingy map, whit the mid set at 0.5 and the scale set at 0.25, I then took this map into PS, and brought it down to 16 bit, making sure the mid gray was the same as on an exported 16 bit map.

Now this is the result we get, when my friend here render it out in vray:
http://www.henrikbclausen.com/kyklop_16.jpg
http://www.henrikbclausen.com/kyklop_17.jpg

As you can see the details are all there (lets look away from the fact that the UV could use some work), and the shape is there. However, these strange lines have started showing up, I am sure you can see what I mean. So my question is, how do I get rid of these, so I’ll get my smooth mesh out?

But, to make matters worse, especially because I am such a huge fan of zbrush, he took the high ress model and low ress model and generated a displacement map in mudbox, and this is what came out:
http://www.henrikbclausen.com/kyklop_14.jpg
http://www.henrikbclausen.com/kyklop_15.jpg

As you can see, this looks fine (could use a little tweaking, but besides that)… I really hope someone out there has got an answer for this, would be much appreciated

[Storm]

I solved the problem, with a little help from a kind man over at cgtalk, who pinned down the line problem.

[http://henrikbclausen.com/kyklop_20.jpg](http://henrikbclausen.com/kyklop_20.jpg) [http://henrikbclausen.com/kyklop_21.jpg](http://henrikbclausen.com/kyklop_21.jpg) No weird lines, the shape looks right and all the details are there!

So just to sum up the progress, in case anyone else should find themselves having similar problems, I’ve made this little pseudo tut step by step for getting the map right:

1. Go to lowest SDiv 2. Go to set the size of the UV-map 3. Set the Displacement menu like this:

[[](javascript:zb_insimg(‘174416’,‘displacementsetting03.jpg’,1,0))
The gamma is corrected to make sure we get the right 50% gray.
And that’s it.

Now what I don’t get is why I can’t play with the scale bar (under displacement in zbrush) unless I use 32bit, because the scale was really what made the difference.

And just to point it out, the first post shows what happens when I just exported the map as 16bit without changing any settings in zbrush.
And the next what happens if you set the scale, mid etc right, but leave smoothUV on.

Attachments

[Kerwin]

Glad you figured it out! I hadn’t though that it was 32-bit centerpoint problem, but now that you’ve explained it I can see how the map has to be manipulated to come out right.

-K