Displacement + Approx render Issue.

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  02 February 2013
Displacement + Approx render Issue.

Hello folks,

Been working on Maya 2010 for some time now and have been using Zbrush for sculpting and creating maps.

I've been having an issue with this particular character. When i apply the surface approximation my model renders invisible. I can see it in the Alpha channel but not in the regular render view. When i remove the approximation....it reappears....le sigh.

I have also used this technique i picked up from a forum which uses this expression:
addAttr -ln "miExportCCMesh" -at bool mentalraySubdivApprox1;

It worked the first time i tryed it, Unfortunately it did not work the second time around. Most of my models have been completed without issue. This issue, however, is driving me mad.

If anyone knows an effective solution or work around.... please help =). I have searched high and low on the net and can't find anything.

NOTES:

I am using GoZ to work between programs and multi map exporter to export maps from zbrush.

With the color map alone the model renders. When i add the normal and displacement maps it disappears from the render.
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Last edited by EGSilva : 02 February 2013 at 07:19 AM.
 
  02 February 2013
Check your map displacement paths.
 
  02 February 2013
What exactly do you mean by checking map displacement paths?

Do you mean to make sure the file node has the right file loaded to it?

Checked and made sure all nodes had the proper files loaded.

This problem occurs when the normal and displacement maps are loaded.

It's an annoying issue. I really like what zbrush does for my work but problems like this really discourage me from venturing beyond just modeling and animating; but i want to learn this and be able to compile notes so i don't find myself up against a wall; crippling my work flow.

One last note: i have 7 subtools and in Maya the UVs are mapped onto 0-1 range for all the subtools (which are also separate pieces in Maya; grouped together) Would my setup cause this problem?
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Last edited by EGSilva : 02 February 2013 at 09:22 AM.
 
  02 February 2013
Ok,

After fiddling with this wretched problem for a few hours i figured out a work around.

Now, this is absolutely stupid, kind of/ kind of doesn't make sense; but here it goes.

Apparently when you transfer a mesh back to Maya from Zbrush using GoZ, a shader node is automatically created for you in Maya's hypershade. This is great, but the annoying thing is that it creates a shader for every subtool you import from Zbrush; even if you import them together using the "All" button in the Ztool menu.

My initial response was to delete these shaders and create my own so i could make my connections and apply the shader to the model. This is where things went wrong.

I tried this same approach again, only this time instead of deleting the auto-created nodes i kept one and made my connections with that shader.

I created my approx. node, applied the attribute with the expression i picked up on the forums....and POW, it worked!

NOTE: Before rendering set your model to the lowest preview setting. If you render with your model set to smooth preview, your texture will appear swirly and distorted. At level 1 it should render just fine and as if it were smoothed.

Yes, a strange work around indeed. If anyone can offer further insight into what is going on here, i welcome and appreciate it.

In the mean time i hope this bit of information can help others prevent the amount of frustration i went through today.

ONCE AGAIN: Use the shader created by GoZ when you import your model back to Maya. If you use any other shader you may run into problems as i did.

Even stranger is the fact that not all of my models presented this problem, so it is an issue that may have been caused by the way i modeled this. To my knowledge, however, my meshes are clean and all quads; little or no triangles. But they are non-minafold, be aware that such geometry will cause this problem.
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Last edited by EGSilva : 02 February 2013 at 10:15 AM.
 
  02 February 2013
Sorry for my short reply. But it sounds like you figured it out.
GoZ sends to your user directory on C: so you will have to repath it. Also, if you do a lot of back and forth with GoZ .. you will need to go to (in Zbrush) Preferences/ GoZ/ Clear Cache files so you don't get the wrong displacement map. 16bit always works for me,. not 32

What I usually do is GoZ to Maya/ select that mesh in Maya,.. ctrl+c (copy) and paste it into the main character scene. This keeps the original displacement map and its values connected so I don't screw it up. Remove the parent node group it creates.
If I'm using the renderfarm, I'll use our proprietary tool at work, or in your case, use File texture manager melscript from creative crash to put it on the network so the renderfarm can see it. Or do it manually.

Also, I recommend only 3 subdiv's on the mrapprox node or your rendertime will explode. You can make a normal map the same time as the displacement map and GoZ it.. they will be connected. Keep in mind it will add a texture file whether you want or not,.. delete it and add your own.
good luck
 
  02 February 2013
Hey, no worries, either way your comment got me thinking and i began poking around with the project again and it lead to a solution. While the majority of my work has gone smoothly, im sure there are many things i don't know about the Zbrush/ maya workflow. The extra info is greatly appreciated.
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  02 February 2013
Hey, thanks. I'm also testing on my end. I ?? possibly think you can add a mr approx node to multiple objects and set it to 3 default,. (which renders faster), and with a normal map for fine detail. Should work. But make sure the original displacement maps from zbrush are still attached to each object from Goz.
 
  02 February 2013
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