Low Poly to High Poly Methodology - Lost UVs?

Hi, I am relatively new to sculpting, so I need help with something here regarding lost UVs when I was in the progress of making a low poly to high poly character. These UVs got lost for the models which I subdivided to Level 3 (The character, Dress and Cape) and I only realised it when I took the high poly back to 3DS Max.

I created a low poly character model on 3DS Max, and put it into Mudbox for sculpting details. Here is the low poly for reference:

What I did was bring the chest out slightly using Grab tool and also bulge some of the thighs, stomach area and back of the character. I also included wrinkles and creases into the dress garment for details. Here is the high poly version:

My main problem arises here, its the fact that my premade UVs on 3DS Max got lost somewhere along the process of the high poly sculpting method for the character, the dress AND the Cape. I used basic bulging, sculpt and knife tools mostly and as you can see from comparison, the two dont differ much at all so does anybody have any idea how or why my UVs disappeared?

Like I said, I am new to sculpting so I dont have too much experience with it. Too summarise If someone could let me know:
A). On the ultimately better methodology from Low Poly to High Poly character modelling
B). If using certain tools in the 3D sculpting application causes the loss of Uvs to occur
C). If there is a way to get the UVs back on these high density models or if I have to either redo the sculpting with another method or redo peel seams on the high poly sculpts.

Thanks in advance! :)

Replies

  • Obscura
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    Obscura high dynamic range
    Normally, people does highpoly first and lowpoly then. Because the lowpoly shapes needs to conform to the highpoly, and if you do it the other way around, you can't predict what detail will be where on the highpoly, on what size, etc. Also, sometimes the base subdiv level of the highpoly just doesn't have enough density at certain areas to work nicely as lowpoly. Using the highpoly to lowpoly workflow, the uvs are the last step, right before the baking process. You could reuse some parts of the base subdiv level of the hp though, and fix up the problematic areas, but its still the best to uv the lowpoly at the very end.
  • ChristheLancer97
    Hmm okay, thanks for your reply. So would you recommend me to conform my already made low poly and drag parts so it fits in with my high poly for the baking process? Or maybe another way?
    I could essentially also do this in the sculpting software without subdividing the base mesh by using the 'Grab' tool and using the high poly as a skeleton of some sort to shape the low poly to high poly. Ive already got the low poly UV'd but they just gotten lost as I was sculpting, since I thought it would preserve them anyway regardless of how much I sculpt or bring the subd levels higher.

     I mean I just thought it would be a time saver if I used my old low poly model for retopology since Ive already got it UV'd and everything. But if theres no other way, do you think it would be a good idea if I just restart the entire thing and shape the low poly first by using non-detail sculpt tools like Grabbing and Bulging and after Ive defined the model I can subdivide it further and add smaller details? Appreciate the help btw!
  • oglu
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    oglu polycounter
    Just avoid UV destroying tools in zbrush. We are in the middle of a project which requires good uvs on the highres. Worked out fine. 
  • Obscura
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    Obscura high dynamic range
    Is this suposed to be game art or for real time usage, or for some sort of offline rendered stuff?
  • oglu
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    oglu polycounter
    Ultra low gameart. We bake everything from a textured highres to the low. 
  • ChristheLancer97
    Hey Oglu, would you mind informing me of what these 'tools' are to avoid when sculpting? I'm using Mudbox atm, completely unexperienced in Zbrush but I'm sure they'll be similar tools anyway. Fact of the matter is now I have to be more careful when sculpting from low poly :') I am also going for Game art so the initial version for this model is fairly optimized.
  • oglu
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    oglu polycounter
    If you use Mudbox you might just reconstruct the uvs. Mudbox does not create the uvs for higher levels out of the box. 
    If they are really lost just import new UVs in Mudbox. 
  • Obscura
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    Obscura high dynamic range
    I was asking @ChristheLancer97 .
    @oglu may I ask why are you guys texturing the highpoly instead of the lowpoly? Sounds like a lot of unnecessary work. The generally accepted game art workflow is to make highpoly, make lowpoly in some way, unwrap only the lowpoly, bake the normal and ao from the highpoly, and texture the lowpoly. This way you don't have to unwrap the highpoly. 

    I can imagine only one case when texturing the highpoly straight would be necessary. And that case is when you need a higher poly version textured for a cinematic anyways. So the in game version is a bake of that to a lower poly one.
  • oglu
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    oglu polycounter
    We need multiple versions of the lowpoly. Polycount and uvs are changing. 

    We store everything in the highres to get a consistent look. We handpaint a decimated highres in mudbox with some Substance magic on top. Its much easier to paint a highres cause you can read the shapes much better.

    We wont work that way on a "standard" game project. 
  • ChristheLancer97
    Hey there, I just tried to import UVs like you said, checked out some guide for it and it seemed like I just needed to step down to Level 0 on my mesh to get the original UVs back ':). I hadn't tried that out at all initially. It looks like Mudbox doesnt actually keep the UVs as you step higher, which I thought it would but yeah you are right Oglu, thanks for pointing that out.

    It seems odd to me though that it loses the UVs when you bring the subdiv up, I didnt think it would so I thought it would be lost for the lower poly versions aswell. Anyway, I seem to have gotten the exact shape I needed for the lower subdivision urgh... Thanks for your help guys, hope this wasnt a complete waste of time for y'all! :D

    One more thing, bit of a dumb/curious question but I've tried looking everywhere for this answer, could I possibly use the blocky, Pre-Nurms version of my model (shown in the image below) for baking high poly or is it a necessity to utilize the first level 0 subdivided version? This is just for optimization and so I can get the same smoothness of the subdivided mesh for in-game use while having it be the very base version.. I've always used subdivided version instead of the very base one.

  • oglu
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    oglu polycounter
    Mudbox does create the uvs if you do a recreate level uvs. Its in the UVS tab.

    https://help.autodesk.com/view/MBXPRO/2019/ENU/?guid=GUID-AFE05480-6AA0-455F-B69F-0F4125CC772A


    Or if you turn UVs on in the subD optionbox.
    Or if you start to paint on the mesh. 
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