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CRoland
07-22-2008, 08:18 PM
Hi !

I'm still new to the world of 3d and I need some advice for rendering with displacement map in Blender. I bought the Gnomon's dvd Head scuplting and texturing in Zbrush. I've created everything I need, I have my mesh imported in Zbrush with the specular, color, bump and displacement map. The problem is the inscrtuctor is using mental ray and maya for his final render and I don't have those expensive software, so I'm trying to do the same thing with blender rendering engine. I'm able to set up all my different maps except the displacement map. I've made some research on how to set up displacement map, but I haven't found a nice looking way to make my displacement map affect my mesh to make it look like it was in the highres Zbrush version. My guy have the bubble man syndrom and I don't know what to tweak and how to tweak the differents values to make it look right.

Can someone help me or refer me to a link where it explain the process to set up a displacement map in Blender that will make your model look like it was in Zbrush.

Thanks for your time and I'm sorry for my bad english, it's my second language so my sentences may look strange sometimes.

Joat
07-23-2008, 02:39 AM
To use displacement mapping in Blender with decent results would require a really high resolution mesh to apply it to. I think you are actually after normalmap, since it seems to be the normal technique to do the thing you are doing.

I hope this will give you a head start, since it's not possible for me to check the settings from Blender at this time.

Michael-Williamson
07-23-2008, 09:38 AM
Unlike mental ray there's no "micro poly" displacement in blender. there is an "adaptive subdivision modifier" in development that tries to only divide what is needed at render time. (search for Kai Kostock adaptive subdivision i think) that aside....

This method will work but as joat mentions will lead to heavy polycounts and large memory consumption at render time...

Go to the edit buttons and look for the "modifiers" panel.
Add a "subsurf" modifier. you can set different amounts of subdivision for the viewport and for rendering, handy for keeping it low polygon whilst you work.
bear in mind that the subdivision level in z-brush is different to the level set here.

it's been a while, but as I remember in z brush, each quad is divided into a grid with as many x and y divisions as the "subdivision" level.
In Blender each subdivision level splits each quad into 4 recursively....
to illustrate the difference:
subdiv level 3 in z-brush = (3x3) 9 quads for each original quad
subdiv level 3 in blender = (8x8) = 64 quads for each original...

next add a displace modifier and set the texture to one containing your displacement map.

The mid level sets what tone = 0 displacement , this will allow the displacement to push in as well as out and avoid the "inflated blob" you are experiencing. You should have a value for this if you pay attention when generating the displacement mao in z-brush... I can't remember where, but it definately tells you the mid point.
less than this mid value will push in, larger will push the mesh out.

the strength is how far the object displaces. depending on the difference between your base mesh and hi-res sculpt you may only need very small values here.

Don't use displacement in the "material" as I think it's broken.. certainly gives unpredictable results and doesn't have the mid point.

If you find or build a version of blender with the adaptive subdiv patch then simply use that instead of the subdiv modifier mentioned above. I haven't used it, so can't let you know about what settings might be needed!

Good luck

CRoland
07-24-2008, 03:41 PM
Thanks for your answer. Finally, I didn't manage to get my displacement map to work as I would like, so I exported a version with bit more polys and a world spaced normal map. You can see in the attachement what is the result. I'm still a noob, so don't expect something too fancy ! I think my biggest problem is I don't really know how to light a scene and how to create good shaders material. I've set up my material the best as I could, but I'm really a newbie in enveything that is related to rendering. The lightning is a bit random because I do not have any foundments and knowloedge on how to light a scene properly. This is supose to be an orc, but it still look human because the way I lighted the scene, we can see all the normal map details (when I'll add teeth and eyes, it will also help to make him look like an orc). So I would like to know you have any good links that will help me to get a basic knowledge of lignthing/shading/rendering foundamentals. I would like to learn how to create good materials and how to place my light to make good renders. Does anybody have good links of articles about the subject foor noobs like me ?

Thanks again !

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07-24-2008, 03:41 PM
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