Overall guidance in retopology, UV:ing & texturing

[Blacktip]

Hi. I really need someone to explain how things work when it comes to getting control over details over textures etc. My current workflow is this: model in Fusion 360 -> export to .STL -> import in Keyshot 8 for texturing/lightning/render. This all works fine for the most of the times, but what if I want to achieve a worn/rusted look on say; the corners of a metal surface? Enter UV-mapping. Or, at least that's what I *think* I need to do. I do not want to make my models low res game-ready or anything like that, but just be able to add grit/dust/scratches on say… edges, creases etc.

So, after scrubbing through hundreds of various YouTube-clips, reading on forums etc I have narrowed my knowledge down to the following:

Since I use a solid modeller (spitting out wireframes that consists of a bazillion triangles), the wireframe can't be used to create a mesh good enough to get a UV-map (that I later can paint my own texture on to. So, there's this thing called retopology which includes a lot of manual labour, pushing quads around and that later can be relaxed in a flat wireframe suitable for adding texture(s) on.

The thing that no-one really has managed to explain to me is the progress/work flow afterwards. If I do manage to retopologize my F360 model in a nice mesh, and also manage to create a UV-map (?), how should I think about a.) the original, hi-res model and b.) the low-res retopologized mesh and c.) the UV-map (bitmap)? I've heard some term called "baking". Is that something you do in order to create a texture-package to bring in to Keyshot?

So, what I want to know is the following: What's the recommended workflow and what tools to I need to learn in order to be able to get full control on this texturing business?  I did have a look at 3DCoat which seems to be able to bring in a .STL, add textures etc and save out some sort of texture-package for further rendering in KS. The UI of 3DCoat was *very* confusing though. I have also looked at dedicated retopo-tools such as TopoGun, as well as reading about retopo:ing in Maya, Blender etc. And then someone recommended Substance Painter for dealing with texturing/painting.

As a total newbie in this area, I really could need some help on how to get things going. Or should I just forget about the hassle to learn all these new tools and just stick to what KS has to offer? I'm attaching a few screenshots of models I've done the past year so that you can see what I'm talking about. And yeah, it's all "hard surface-stuff", i.e. no monsters, ogres and things like that

[bharris]

Rather than try to UV wrap a parametric model like that, a better option might be to experiment with the curvature node to show a different material through on corners/edges. Another option with perhaps more control depending on how much time you want to spend in Keyshot, is to render the model with both a pristine look and then one of complete rust/worn material. Stacking the images in Photoshop, you then can mask the areas to show the worn material through the paint/metal/etc. Gives you more control after the fact.

Great tutorial by Esben on the curvature node to create a worn look: https://www.youtube.com/watch?v=sfuTOYZbYQc

[Blacktip]

Hi, and thank you for the reply. Yes, I understand that you can achieve some great results of "wear & tear" using Esben's technique. Rendering out two (or more) versions of a still image and in post paint in desired grit is another way that – as you point out – could be a very precise way to get a more realistic look. I would however like to understand the most efficient way of dealing with the ability to "paint directly on the model" and/or "paint whatever texture I want onto a flat texture-mesh" (for later rendering in KS.

I did actually (after a glass of wine, or was it two glasses?) purchase a copy of 3D Coat (which actually allows me to import a F360 model and then paint directly on the model). Still need to understand the export of textures and whatnot for further final rendering in KS. The UI in 3D Coat is far from user friendly, and I've experienced a lot of crashes when doodling around so far… so no, not a perfect solution in my eye.

I wish KS had some sort of "paint per pixel/vertex painting" built in, but that's perhaps for a release in a very distant future.

[RRIS]

Honestly, I'm not sure I would bother with the texturemapping/unwrapping process. Like bharris says, using the curvature and occlusion nodes you can do most of the dirt/grime/rust application and I'd use labels for everything else.