Skin modifiers doesn't allow render

[Anonymous]

Hello,

So I have created a character and imported it to 3Ds Max. I turned it into an editable poly, added an unwrap UVW, added a turbosmooth after that, then a displace and finally a skin modifier.

And I have just realized that my scene would not render (the render window doesn't even appear, the program just becomes not responsive.

By deleting these modifiers 1 by 1 I have figured out that the problem is in the skin modifier since the project renders if if i delete it.

What are my options to fix this without deleting the pose that I created so I can render my project? (I am using v-ray, I don't know if that matters).

[Alfred.DeFlaminis · Accepted solution]

Hello @Anonymous,

Deja Vu, did I see this same post on CGTalk?  🙂

The problem here is that you have your modifiers in the wrong order.  Turbosmooth should be on the top of your stack (or at least near the top.)  I can't imagine the amount of work skinning this was with all those extra verts.  Your stack should look like this  (made to look like 3ds Max modifier stack)  Is your displace a VrayDisplacement Mod?  

Displace

Turbosmooth

Skin

Unwrap UVW

Editable Poly

I believe that the problem is the turbosmooth on the skin.  Can you please try this for me and see if it helps?  Thank you!

Best Regards,

[Anonymous]

Hello, yes you have probably seen the post before :$ once nobody answered me here I posted in CGtalk in hopes of help.

And oh wow that was the problem 😐 Thank you very much. It wasn't a problem because I would sometimes disable the turbo smooth when painting weights.... I guess that should have been a hint... oh gosh

No my displace is not a VrayDisplacement Mod, I'm having trouble with that too. I tried to apply a VrayDisplacement Mod but I doesn't seem to work. Maybe the order of the mods is why? I followed this post, re-arranging the mods and deleting and remaking them as the order asked. But It still wouldn't work. I remember I got it to "work" somehow but it would inflate my character equally through out. So I eventually gave up and tried with displace mod. Still doesn't work correctly. There are mistakes under her chin for example because I need to apply displacement using UDIMS. But I can't find online explaining how to do it. So If somebody could help with this too I would appreciate it. (Sorry)

This is what I followed:

1. add a 'Unwrap UVW' modifier
2. click the 'Open UV Editor...' button.
3. Select all of your UVs (Ctrl+A). Then go to 'Tools -> Break' to break apart all your UV edges.
4. Add a 'Turbo smooth'
5. Set Iterations to 0
6. Check 'Render Iters' and set it's value to 3.
7. Add a 'VRayDisplacementMod' modifier to your object.
8. Check '3D Mapping'.
9. Click the 'None' button, and choose 'VRayHDRI' from the Material/Map Browser popup.
10. Open the material editor and drag the VRayHDRI button to an empty material editor slot and choose 'Instance'
11. In the VRayHDRI's properties, select the '...' button next to the bitmap box and load in your displacement map
12. Set the Color Space group to 'None'
13. Leave all other settings to their defaults.
14. Back in the VRayDisplacementMod modifier, Uncheck 'Filter Texmap'
15. Set 'Edge Length' to a value of 4.0 to begin with, and lower as needed for better displacement quality
16. Check 'Keep Continuity'.
17. Set 'Texmap Min' and 'Texmap Max' to values starting at -1.0 min and 1.0 max.
18. Leave all other settings at their defaults.
19. Open the 3ds Max Render Setup window, go to the 'V-Ray' tab, and open the 'Global Switches' rollout. Make sure that the checkbox next to 'Displacement' is checked.

[Alfred.DeFlaminis]

Hello @Anonymous,

Yes, sorry for the delay.  I've been getting a lot of posts lately that require a significant time investment (which I have no problem with) but that means I'm a few days behind answering new posts.  It's a cause of concern for me as well.  

Ok that being said, I don't see anything specifically wrong with your setup that you listed, but a formulaic approach is hard to follow sometimes.  I don't think you need to break your UV shells though.  Whatever you got out of Zbrush should be fine.  (Or mudbox, whatever.)  I could be wrong about that since I can't see the actual file but I don't generally do that in my work. 

The reason that your model got inflated with the DisplacementMod for Vray was because in a general sense you need to factor in the negative displacement.  For example, if you are displacing 16 mm, you need negative half of that as your 'shift'.  I have a screenshot below.  If you'd like I can create a private folder for you and check the file if you're still having skinning and crashing issues.  Happy to help!

Best Regards,

[Anonymous]

The skin issue is totally fixed. Though I can't make the vray displacement map work. I tried applying shift like you said, makin it (-amout/2), tried many diferent values too, but weird things keep happening to the mesh and I don't know what values to adjust to fix this.

[Anonymous]

After posting this I realized that I should try  smaller values, the weird distortion seen on those photos I posted before has been fixed, however, there is still no displacement happening.

I tried using the values "amount" = 0,016 cm and "shift" = 0,08 cm. No distortion happening, however no displacements happening eather. After that I tried making the amount value a bit higher but without touching the "shift" values nothing seems to change, and if I do change the "shift" values the ear starts getting thinner and loosing shape. If I go too high of values for both "amount" and "shift" I starts happening the weird distortion again.

Is there some other thing that I am missing? Or am I doomed to keep on trying out random values until something works?

the 1st image is the best result I can get from the v-ray displacement mod. And the second image is what I got out of the regular displacement mod. (the ear there had weird jagged edges but I added another itineration on turbo smooth and that no longer happens)

[Alfred.DeFlaminis]

Hello @Anonymous,

I'm glad the skin crash issue is worked out, I'm going to mark the solution but keep helping you with the displacement issue in this thread.  I wonder, if I create a private folder for you, could I check out the files?  Did you create the displacement in Zbrush?  What bit depth is the displacement map?

I have set up a private folder for you if you'd like to upload your files there. You should get an email about it shortly, and if you don't see it please check your SPAM folder. These files are private and will not be shared with anyone but yourself and the support staff. Please let me know if you have any questions. Please use at least an 8 character password or the Box account may not work properly.

Best Regards,

[Anonymous]

Hello, thank you so much for your help.

I rendered the displacement maps in Zbrush, i'm not sure if this is the information you asked for but I think I rendered the image as a 32 bit EXR. file, with the mid value set at 0.

I managed to make the displacement map work a bit better using the displacement mod, it is still not perfect, but due to my lack of experience i'm starting to think my geometry maybe is not good enough to change this much simply by using displacement maps. The biggest issue seems to be the mouth that is supposed to be closed.

Still no progress using the vray displacement mod.

I managed to use Udims by applying into the modifiers a "composite" with the 2 bitmaps in it, instead of applying a bitmap or a Vray HDRI directly. (when I do apply a bitmap or a vray hdri directly the problems continue so i don't think this is the issue) I'm not sure if this is the best method but it was the only way I managed to find out how to use Udims.

Thank so much for helping me out and i'm sorry for always posting for help.

(I have posted my file. please ignore my horrible attempt to try and pose and adjust weights on the character, I just need some practice and patience)

[Alfred.DeFlaminis · Accepted solution]

Hello @Anonymous!

Please don't be sorry, part of your subscription fee is paying my wages and to be honest, I work for you.  I like helping people and it's a nice job, so I have no complaints.  🙂

For the UDIM displacement you might need to check on the Chaosgroup forums, I'm rusty there.  I did however see what I think is the issue with your displacement map.  Normally a zbrush displacement map has 127 gray as the middle value.  Displacement maps can go in both directions, but since your base color is black yours actually shrinks the model and then grows outward.  No good.  Adjusting the displacement amount probably won't solve the issue because the map itself would need to get weirdly blown out to fix this, and then other problems can crop up.  

You'll have to refer a bit to the Zbrush forums, but there should be a way to export your displacement with middle gray as the neutral tone instead of pitch black.  I am confident that this is the source of your problems (or at least the majority of them) and continuing on is too hard without an updated displacement map out of zbrush.  I have a google search here to show what it should look like (see the various screenshots where there is no height info, I.E. outside the uv shells).  A displacement map of 127 would likely do nothing and then black goes inward, white goes outward on the map.  This way you can get displacement going in both directions.  You're goes only in 1 direction, but first it pushes everything inward.  Am I making sense?  

EDIT: Grammar.  I wish I could type as fast as I think.  

Best Regards,

[Anonymous]

Indeed you are making sense. Thank you. And thankfully I already know how to export the displacement maps using the grey and not the black. I'll try exporting it correctly and applying it in the morning, and leave an update of the situation here.

Crazy, I had read in multiple places (random forum posts and such) that for the displacement map to be read correctly in 3ds max it had to be black, that's why I was doing it that way. :$ Its funny really...

[Alfred.DeFlaminis · Accepted solution]

Hello @Anonymous,

Ahhh I see.  The displace mod for 3ds Max would prefer that since it's using the luminance to push the faces a bit, but render displacement is a slightly different beast.  That's where I think the confusion was, and you were doing what was written so no blame to you there.  I'm glad I could help a bit about this!  Once you have a new map, if it's still wonky just put that map in the folder and I'm happy to keep helping!

Best Regards,

[Anonymous]

Success! It took me some attempts to export the displacement maps correctly from zbrush. But I managed to do it and it worked. Thank you very much. No more problems here. 🙂

[Alfred.DeFlaminis]

High five!  Nice work @Anonymous, thanks for being patient as I worked my way through this one.  I'm glad you are all set now!

Best Regards,