Noob Zbrush/Render-to-texture questions

Kindri

Well I'm just full of noob questions these days Though I suppose sucking it up and looking foolish now will make me a better artist in the future. Also thanks in advance to those who take the time to help out with these beginner questions.

I just got Zbrush last night, so I'm new to the whole normal mapping from high-poly thing. I started with a low-poly (and UV-unwrapped) model, however I tessellated and converted to editable poly before I exported to Zbrush, and I think in the process I lost my UV information (oops). So I did my high-poly sculpting, only to import it and realize that my UV information hadn't been there.
I now have my low-poly properly unwrapped, but projecting normals still doesn't seem to work. Am I stuck going back and re-doing my high poly work? I don't mind if I have to, but I'd rather avoid it. Thanks in advance.

Kindri

Nevermind I think I've gotten it worked out with xNormal :x

jogshy

Kindri wrote: »

I just got Zbrush last night, so I'm new to the whole normal mapping from high-poly thing. I started with a low-poly (and UV-unwrapped) model, however I tessellated and converted to editable poly before I exported to Zbrush, and I think in the process I lost my UV information (oops). So I did my high-poly sculpting, only to import it and realize that my UV information hadn't been there.

I think ZBrush can UV-unwrap your highpoly model. It's called GAV/GAUV/GUV tiles or something like that.

But yep, usually the highpoly does not need UVs. You can use xNormal to render the normals. Only the lowpoly mesh needs to be UV-mapped ( usually, unless you need the "bake highpoly base texture" feature which is an advanced thing... or you use the Simple AO GPU Tool without the per-vertex option ).

You can also use Maya's transfer maps or the 3dsmax's Projection modifier+render to texture ( I think XSI and LW have also a similar tool too... but i'm not sure ).

Btw, usually to render a good normal you need to avoid UV mirroring(some applications and 3d engines don't support it... or it's kinda problematic... but it can be done if you're cautious ) and to be sure that you don't overlap the UVs ( unwrap the UVs = good ).... and use xNormal or 3dsmax "cages" if possible... usually "distance-based"/uniform-constant-max-ray-distance methods are only good for non-organic models(like boxes,cylinders,spheres, etc...).

I hope it helps.

Kindri

Thank you jogshy - I really appreciate it! I thought I had things figured out with xNormal, but I'm having some sort of overlay problems which have been really frustrating. I'm gonna sleep on it, and try to sort it out tomorrow with your suggestions in mind. Thanks again

jogshy

Ask if you have any other doubt about xNormal, I'll be glad to help you.

Kindri

Ok I'm still having some problems
I used xNormal to generate my map - however, there still seems to be a lot of weird differences between my UV and the generated normal. There are legs/arms in the middle of the body, the eyeball is not an eyeball and basically everything is just a total mess. Anything I can do to fix this?
At this rate I think I might just redo my UVs and high poly, as it'd be good practice anyway - but I'm still curious if there's any way to fix this in case I run into it again in the future.

kary

On the 'low definiton meshes' tab do you have 'use cage' turned off, and fairly small numbers in the maximum frontal ray distance, and maximum rear ray distance?

Kindri

Thanks kary, I tried with and without cage, and messed around with various ray distances. They are starting to look much cleaner now - however, no matter what I do, I always have extra arm and leg information right in the middle of the body, even though it doesn't correspond to my UV at all, so I'm not really sure what's going on there.

EarthQuake

try turning down the ray distances really low. You may want to do 2 renders, one with a high ray distance and one with a low, then composite them together in PS. Also the eyeball looks like its inside of the head mesh, so thats always going to give you errors, its intersecting the other mesh. Whatever you see the raytracer is going to see. So if you look at your model, and only see a section of hte eyeball because the rest is hidden behind the head geometry, thats what the raytracer will see as well. Unless you have reallllllly low ray distance settings.

Kindri

Thank you for the advice! I will try that next. As for the eye issue - how would one normally go about preventing that? Should the eye be kept as a separate object?

kary

Keeping things separate would be helpful, and you might be able to apply some of the concepts from EQ's weapon tutorial here: http://boards.polycount.net/showthread.php?t=53938 to what you're doing. At least if you think of the eye as one part of the gun, and the body as the rest It's very helpful to know for a character with props etc.

Kindri

Thank you kary - good to know!
I appreciate all the help that everyone's given me on this. While I've been able to get the normals looking a lot better, they're still pretty wonky and I think I really just need to go back and re-do it, and separate the eyes and teeth and such before I start. Learning process I guess
I decided to go ahead and paint my low poly, I think he's kinda cute so I might just keep him without a normal and apply all the new high-poly information I've learned to my next model - I haven't decided yet
Thanks again guys

diffuse:

Michael Knubben

I hadn't had this problem for a while, but suddenly it happened a few times in a row again:
Sometimes, the render (of a normal map) will finish, but the close button is still grayed out, and the stop button is still 'clickable'. Also, the big green/red button is still red and says 'abort'. Pressing stop or abort won't actually do anything, and the only thing I can do is kill the process, and hope it doesn't happen the next time.