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Freemorpheme

Unwrapping a sculpted mesh

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Hi there, 

 

I thought I would make a rock to practise making something in C4D and sending it to Substance and rendering with Octane. So I made a low poly mesh and used the sculpt tools to make a big blobby rock with 2 levels of sculpt subdivision.

 

When I brought in a premade Substance, it looks OK at a distance, but up close its a bit of a mess. I have to use Cubic mapping to get anything, as the UV mapping is horrific.

 

So I thought I would unwrap it and actually send the mesh to Substance Painter to texture it. 

 

My question is, what is the workflow to unwrap a sculpted mesh? Should I make the hi-res mesh editable and use that? Should I have unwrapped the low poly box mesh first before I sculpted it?

 

I see a lot in Substance workflow instructions about 'low poly mesh and high poly mesh', is this what they are talking about? Should I save them separately somehow?

 

So many questions, if anyone can help, thanks.

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Generally speaking it makes no sense to UV a sculpt - whilst technically possible it is practically implausible to be shifting around what could be millions on milllions of polys in a UV layout window with the rather limited tools we have available...

 

However what makes excellent sense is to UV the base mesh, which is actually a requirement of successful baking of sculpt objects in Cinema (if you don't use the auto methods). But is there any point in UV'ing before you sculpt ? I'd say that depends on how close the shape and form of your base mesh is to what you will be sculpting later. So if you have a low poly figure you will be later sculpting additional minor detail into, then you could reasonably UV that before sculpting. But if you start with a cube, there is no point in UVing that if you then subsequently turn it into a totally unrelated form during the sculpt. In that case you would do your sculpting, then bake out to a higher level than 0 that did roughly approximate the form of your high res sculpt.

 

I don't use Substance yet, so am not the person to tell you the best workflow there, and what it does with hi and lo res meshes, but that is the thinking behind the sculpting / UVing plan, which might clarify some stuff before you get there...

 

CBR

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  • Thanks. Here are pics of the low poly, high poly and textured mesh so you can see what I mean. You think I should have UV'd the original first? 

    Capture copy.jpg

    Capture2.PNG

    Capture3.PNG

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    1 hour ago, Freemorpheme said:

    You think I should have UV'd the original first? 

    Er... no - I'd say that is a little too far removed from the final mesh to be a good UV map. TBH if that 3rd pic is your sculpted final that doesn't have millions of polys so maybe you could make it editable and UV unwrap it from there, although seam placement is a little challenging on that mesh.

     

    But I'd wait for someone with Substance experience to advise you further because they may have legitimate reasons why you should keep a low poly mesh...

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    Hi @Freemorpheme, there's 2 ways to go about this:

    - You sculpt whatever you want and then retopologize (and then UV the retopoed version. Then project the mesh details of your high poly sculpt on that retopoed version via raycasting, which in turn will generate a new high poly model with the proper topology and UVs. Then you bake the maps of this model and use the normal &/or displacement map backon the low poly retopoed UV model)

    - You have a base shape in mind and you create the right topology from the start. When the shape looks alright you UV and check the result with a checkerboard texture to check for problematic/stretched areas. If happy, you duplicate your model and subdivide it further to start scultping until you have what you want. Then, most often you end up baking the maps of the high to the low poly.

    So the note is:  You'll never be able to UV efficiently if topology doesn't allow you to. Good topology makes your life easier every step of the way.

     

     Finally for a rock in C4D start with a Hexaedron sphere, use an FFD defromer to taste and a displacer deformer with a noise to get you started. Keep everything parametric until you have an acceptable shape; UV that, test it with a texture, and then start step 2 above.

    You can bake the high poly maps in Substance later.

    Hope that helps

    VH

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  • Thanks, I think I get all that - apart from this bit: 

    1 hour ago, Vertex Helix said:

    project the mesh details of your high poly sculpt on that retopoed version via raycasting, which in turn will generate a new high poly model

    What is the process for this? Is this something done in Cinema?

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    Just thought I would mention that you can still edit the UVs of the base mesh while it is being sculpted. The changes will be propagated through to the higher subdivision levels.

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    @Freemorpheme it's in your sculpt layout menu near the bottom: Project mesh (that's via raycasting)

     

    In the new menu you will be asked for Source and Destination mesh:

    You choose a subdivision for the new model C4D will create, that matches the poly count of the source, but the new model will share the same topology and UVs as your destination mesh while preserving the sculpted detail.

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