ZBrushCentral

problems generating displacement map/very slow

ZBrush Usage Questions
#1

I am attempting to generate a displacement map out of z as per the instructions provided. When I attempt to use the dsubpix the map generated looks as if it never made a difference between the low and high res mesh as is void of any detail. I figure I need to use addaptive but my map will not be created for about 3 days. Is this common? I attempted to hide part of the mesh or even delete the highest subdivision level but it seems to only save me about a day.

I am running on a duel xeon 2.4 with 2gigs of ram

#2

This should help.

Also, if your map has no detail, then it’s probably that you are at the highest subdivision level when you create it. See the Displacement FAQ here at ZBC for more info.

#3

I am at the lowest sub level and have switched to morph target.

I read over the threads you mentioned and if I only had to wait a few hours that would be no problem but three days seems a bit excessive even for adaptive. Using dsubpix takes anywhere from 20minutes to 3 hours depending on the level 1-4, which is fine if it produced a usable map.

I attached the image file generated and the lo and high res model image.

Attachments

billyhead-s20-1-6.jpg

sheep lo hi.jpg

#4

Looking at your images, I am getting the feeling that there’s something wrong with the UV coordinates. Could you show an image of your UV mapping? Have you tried running the UV Check routine found under the Tool>Texture menu? Do you still get the same long times if you assign GUVTiles or AUVTiles for the mapping?

#5

I did the uv check again and attached the image below. If there were problems they would be presented in red, correct? When I uvmapped the character I ensured that overlapping uvs were visable.

I also tried the auv tiles, it seemed as though it may save an hour or two.

Attachments

uvmap.jpg

#6

Those times are WAY to long and I have never had anything close
to those times. I feel bad for you. How many polys do you have in the hiRes?
What size map are you rendering? Are you using adaptive mode? What is your
dpSubpix value? Whats you proc speed.

#7

Ditto, I’ve been creating a ton of displacement maps over the past month at 4096x4096 off of meshes with betwene 6 and 8 million polygons (with 6 and 7 levels of subdivision) using adaptive mode at the level 1 mesh. Longest map generation time has been around 30 minutes on a dual 3.6G w/ 2G ram.

Same maps generated using dsubpix setting of 4 increases time to about 3 hours. Adaptive seems to be much faster - is that always the case ?

I’m also using zbrush guv mapping - does the mapping method make any speed difference ?

#8

I may have discovered the problem, unfortunately the solution may be a problem. On a hunch I deleted my morph target and rendered my map. It seems to have worked fine. Problem being that now my original low res cage is not used in the generation of the displacement map.

When I imorted my low res model originally I had forgotten to save the morph target. As I worked the model I realized my mistake and reimported the lo res into sub level 1 and saved the morph as per instruction page (as per instruction on page 196 of the practical guide, which I believe is inaccurate as you cannot load tool into but rather you have to import into sub level 1, of course I could be mistaken). Anyway someting went wrong in this process.

As far as I can tell now my only solution is to start from scratch, unless I can get somethig else to work.

#9

Dadagda,

Are there morph targets assigned to your original low rez mesh ? What animation package are you using once exported (subD method) ? Is your pipeline such that you can’t use a low rez cage exported from Zbrush at this point ? I’d hate to see anybody have to start over :frowning:

#10

You should be able to import your original mesh into SubD Level 1 and immediately calculate the displacement map. Do not change subdivision levels as that will cause zbrush to recalculate the higher SubD levels.

Storing a morph target is not preferable in my experience. For one you loose the ability to use the Morph and Morph Dot edit modes to accentuate or alleviate detail from a Projection Master drop.

You should have a copy of your original .obj handy for displacement/normal map creation. If you want to assign AUV or GUV tile mapping to your model do so immediately after importing your model into Zbrush. Then save that model as an .obj. This will be the .obj you should import into SubD Lvl 1 before generating the displacement/normal map and also as the .obj that should be imported back into your render application of choice.

#11

There are no morph targets. The program I used to make the low res cage and will be exporting back to is softimage. It may be possible to use the level 1 cage but probably not preferable. This character has a big fat body as well as the inside of his mouth. It was cut up to work at higher resolutions in z. If I were ot use the level 1 cage I would have to stitch back together and can forsee having some bad stretching. Still something I can test. This character is pretty much a test in workflow.

I have just tried this as well but it still rendered out a map just like the one posted above. I am not sure exactly where the problem lies but it has something to do with my original cage or the process of importing it back to level one.

I am not yet done trying to find a solution but do not want to spend to much more time on it. Would rather spend my time modelling. If I do rework it I will be testing much more as I work the model to ensure no porblems.

Thankyou for you time and suggestions guys

Dadagda