Delaney King

Delaney King

02-11-2022

08:02

#Gamedev tip- I see a lot of videos where artists sculpt high frequency noise onto objects made in zbrush. Things like the rough texture of stone or rust on old metal. Here is the thing...

That fine noise goes into your main texture bakes. Your normal map, therefore, needs to be really big to record that detail. Okay, so what is the problem? Well, you don't actually see most objects up close all the time, and so to speed up filtering, we store MIP MAPS.

A MIP map is a prefiltered scaled down copy of your texture that is used when you move away from your model. Rather than having to process 4k square of pixels, it only has to work with 2k. As you move further away, the next mip is used which is half again, and so on and so on.

You can usually see MIP maps kicking in on a flat floor plane as it stretches off into the distance- you may have noticed a point where the floor seems to get a bit fuzzy. That's the next MIP map being used. So why is this important with your zbrush work? Well...

Your fine noise is going to be blurred and averaged in the mips, and when you down scale a random noise, artefacts will naturally start to appear as all those iddy biddy pixels of direction vectors in your normal map get all crushed up together. Your lovely stone starts to...

Look like a hazy chuddy random goop. Not what you want, really. The smarter way to bake your normals and get fine details is to bake without all the noise and use a shader to overlay the fine noise textures when you get close.

The second reason I strongly discourage putting in noise in your zbrush sculpt is that it will stop your decimating your mesh down. This means you have to store a *really* fucking big model, and send that through to be baked as a texture, and then sit around in your archive

Hogging up your hard drives and making your check ins and back ups grind. The fact is, if you need fine surface details in your game textures, do it in something like substance painter. This will allow you to dynamically update the noise and adjust it if it looks bad in game

My advice is work to get your primary and secondary shapes in zbrush, add mesh specific stuff like corner wear, damage and cracking, soft curves and sculptural features... but then use your paint program for placing the tertiary details, surface features and patterning.

Here you can see me adding finer details dynamically in substance painter.

A third benefit of not having fine noise in your main baked texture and instead use a shader to add it is that you can reuse the main baked textures in the game with a range of surfaces. You can have, say, a car that is sleek, one with peeling paint, one just rusty.

I hope this helps save you a lot of pain, large files and ugly results.

This is an example of what I mean. The one on the left I captured from a tutorial (not naming because no shamin') but actually the one on the right is a better place to bake your high to low from, not the one on the left.

The one on the right can be decimated with decimation master, and the textures will compress really well at a smaller size texture.



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