Baking normal maps for belts/straps

MrOneTwo

Hey. I tried to look for an answer but no luck. I imagine that's something that has been discussed.

So my main problem is baking straps/belts. I would like to use efficient custom low poly meshes to bake to but making those is a bit of a pain and I think that's the process that can be improved upon. I'm testing this solution in which I use Bevel modifier in Blender on the low poly mesh to get smooth edges - there is no high poly mesh. There is this additional effect I'm missing. This effect is the same one you see when you bake high poly cylinder to a low poly one. The difference in segments gets baked into normal map (on the normal map it can be seen as this wavyness). That's something I can't replicate through this process but I'm not sure it's worth replicating.

So once again with images. I have a low poly mesh on which I put Bevel modifier:

I bake its object space normal map.

Then I remove Bevel modifier and export the mesh as a proper low poly. Here in Marmoset Toolbag 3 (with object space normal map).

It looks good enough (even though I'm missing this additional information from traditional high to low baking). I tried using Handplane to convert the map to Tangent space but couldn't get proper result (needs more testing...).

Any thoughts? I just want to skip high poly -> low poly baking process for elements like belts/straps.

Not sure it's possible or worth it but that's why I'm asking what you think

Thank you!

CrackRockSteady

you could just bake a simple, straight strip of belt geo (a belt trim sheet, if you will).  Then simply unwrap whatever low poly belts/straps you have and UV them to that trim sheet.  It'll save a lot of time and you also won't need to waste a bunch of UV space having unique unwraps for every belt and strap you have.

musashidan

Also, you could just apply the bevel with a single segment and use FWVN.

poopipe

CrackRockSteady said:

you could just bake a simple, straight strip of belt geo (a belt trim sheet, if you will).  Then simply unwrap whatever low poly belts/straps you have and UV them to that trim sheet.  It'll save a lot of time and you also won't need to waste a bunch of UV space having unique unwraps for every belt and strap you have.

Yeah, this^^  
Use the neat strip of texture space you already assigned, just bake it flat. Much easier to model as well. 

The FWN method would work but the geometry cost would be needlessly high for something that you could achieve very easily with a bake

musashidan

poopipe said:

The FWN method would work but the geometry cost would be needlessly high for something that you could achieve very easily with a bake

For a modern character the extra geo wouldn't be that high at all. Plus you save memory by having 1 less normal map. Not to mention all the extra on-cards verts you're going to get from breaking all the UVs up anyway.

MrOneTwo

Thanks guys!

@CrackRockSteady - So something like that? (There are some polygons missing in the bake... don't know why*). And now I would match the UVs of the target belt to this normal map? That might be the best solution (tested this and others).

@musashidan - I don't want to add unnecessary verts because I want to rig this character. Less verts results in easier skinning. I used this technique before and I really like it (it's almost free when you think about the time it takes ;P ) but don't feel like it's the best way. Especially for rigged meshes.

* - Fixed it by triangulating the low and the cage.

So I have matched part of the UVs of the belt to this normal map:

Looks fine. Problem is the UVs matching workflow. That's something I have to figure out and make way better/faster/easier.

CrackRockSteady

@MrOneTwo you'll want to extend the strips all the way to the edges, like so:



This way it tiles seamlessly and you can UV belts/straps of any length to this by extending them beyond the 0 to 1 coordinates.

For the end bits you can find another place on the UV sheet to put them or if it won't be examined very closely you can probably get away with mapping them to the edge strips.

Mark Dygert

In 3dsmax you model that with splines, turn on render geometry, generate UVs (or use the sweep modifier) and you get nicely squared off UVs.

musashidan

Mark Dygert said:

In 3dsmax you model that with splines, turn on render geometry, generate UVs (or use the sweep modifier) and you get nicely squared off UVs.

Don't need to use sweep. You can set it as square and enable it in the spline rendering rollout.

poopipe

Sweep is more controllable in terms of the profile. Plus it can be instanced to other splines so I'm with Eric on this one. 

WRT FWN earlier in the thread . I tend to advise against it because I'm not a fan of their use in a production environment. Apart from the geo cost and the difficulties you encounter when lodding it's an unrepeatable/silent edit - if an artist works on a model authored by someone else that uses FWN or other custom normal work they may not be aware of what's been done and could easily end up breaking things. 
There are good reasons to edit normals of course but to my mind its something that should be done when it's needed, not just cos you can. 

Obviously, if nobody else is going to touch the model there's no problem