Mini Tutorial: Normal Maps and How Not to Do Them

[UnsteadyTeddy]

You could even expand this tutorial to cover the same principle for quick spec maps.

[Talon]

Yeah, probably. I was thinking about doing a separate one for spec but I don't know if I have enough experience with spec maps (well, coloured spec maps) to pretend to be any sort of authority on the subject :P

Although the spec maps done in that way usually aren't *quite* as heinous as the normal maps...

[[hP]]

yes, yes, I know, i was just point out all the three possible ways of generating a normal map on my previous post!

[swag]

Just a little confused here, you recommend generating a heightmap before making the normal map (from say, the NVIDIA plugin) but how would you do this from a more complex model (where you can't hand paint it easily)?

[Talon]

I said you should make a height map that you turn into a normal map. The height map is what you feed into crazybump/nVidia/xNormal - not the diffuse.

If it's a complex model that you can't paint easily, then it's very likely that you'll get even worse results (unless, like I mentioned, it's a really noisy and relatively flat texture anyway - like earth or rocks - and even then you'll get better results from sculpting out the major shapes to bake that).

[swag]

Originally Posted by Talon

I said you should make a height map that you turn into a normal map. The height map is what you feed into crazybump/nVidia/xNormal - not the diffuse.

If it's a complex model that you can't paint easily, then it's very likely that you'll get even worse results (unless, like I mentioned, it's a really noisy and relatively flat texture anyway - like earth or rocks - and even then you'll get better results from sculpting out the major shapes to bake that).

Ok thanks, I understand the need for height maps now (although I was never just putting my diffuse into crazybump without changing some things, but I guess I still left too much detail).

I still would like to know how you made the heightmap for the shoe (in your tutorial), assuming that you didn't paint it in by hand.

[phaselocked]

Very nice, it helped me alot. The only thing I want to see is the diffuse with the normal map applied to it.

Regards

[Talon]

Yes, the shoe height map is hand-painted.

The trick here is that I used a few layer blending effects like inner and outer glow. That helped give the effect that the stitching has been sunken into the surface (as is it's binding down padded material). And on a few other bits to ensure that they look nicely padded and rounded when it gets converted to a normal map.

I could probably have put some more of that detail into the high res mesh to get a better result, really, but it was faster and easier to do it in Photoshop :P

It was then overlaid onto a much more simple normalmap that was baked from a high-res model model (the baked normals represented complexly curved surfaces - pretty much impossible to draw by hand into a height map), using the technique I linked to above in the Project Offset blog.

If your diffuse texture is hand-painted, too, as mine was, it becomes a lot easier to lift parts of it and alter them into a height map, so you should be keeping your layers nicely organised for that. Essentially remove all of the lighting and add in anything else that gets lost in the transition and then you can start to vary the brightnesses to put it together as a height map.

So my diffuse texture actually contains two folders, one for the diffuse texture itself and one that's my height map, created from just duplicating layers from the diffuse texture and altering them to make a height map, which I can then copy/paste into my normal map.

For really complex photo-based stuff, you might want to try overlaying the diffuse back on top of your height map really faintly (after removing all of the lighting you can) so you can reflect some sort of detail in the derived normal map that would just be too tedious to paint in.

[bb0x]

Originally Posted by Talon

Actually, I find this technique gives the best results.

Project Offset - Developer's Blog

Ah I see basically what it does is increases the range of every channel by dividing it in 'negative' and 'positive' layers and disable the negative blues. I havent really read everything on that page.. downloaded the action and checked what it did.. pretty nifty!

[tinokun]

I just tried this the wrong way yesterday. Thanks for posting this.