First steps with normal maps

Aranoth

Hello !

Following my topic in Technical Talk, I did my first steps with normal maps.


I first modeled the low poly version of a chess piece : the Knight.
And then I imported it in ZBrush for my first real sculpt. However I did some mistakes so I was obligated to remade it...



I tried to use ZMapper but the result is strange, some polygons don't get the right normals at all... I think it may come from my model and the fact that I triangulated it automatically without checking.

So I exported the high res version to OBJ and used xNormal instead. Great, it works (but the it's damn slow).



Both textures are in fact 512x512 (but for such a model, it may be waaay to high)

And then the render with xNormal :



Such a difference !

The mane is buggy but at least I know why.


It wasn't really difficult (excepted ZBrush that had a very particular logic), it will continue to practice.

Aranoth

Another one, without ZBrush this time :



And with precomputed ambient occlusion :

ParoXum

Used any symmetry on your pillar uvs ?

If yes, bake your high poly on one part only. Mirror it later to avoid seam.

Aranoth

No, I didn't use any symmetry for the pillar UVs (I used symmetry for the top of the pillar, but UVs were unwrapped after merging the two sides).

Having said that, I must confess I used the automatic projection tool of BodyPaint, maybe the seam come from it.

Snader

the manes on your chesspiece lowpoly seem to be flat planes.. i assume this is what makes the NM buggy

pior

Hi again Aranoth,

You're on a good start, but I would recommend going back to the horse piece and do a few things differently.

First off, you shouldn't make an optimized game model with very specific topology before starting on the sculpt. Instead you should focus on making a very simplistic cage giving you the maximum amount of flexibility for sculpting. If you do your 'final' lowpoly model right from the start, chances are, the silhouette of your sculpted mesh will not match it at all since you will naturally push shapes in the sculpting program - hence, a bad bake.

So try this :
> Make a very simplistic horse shape (but keep it nice and clean, with mostly quads. A 90degrees bent cilinder with rounded ends/sausage is enough for this),
> Sculpt that freely, at anysubdivision level,
> Once done, export your final highpoly as OBJ for a later bake, AND, export a medium level to obj aswell. This one does not need any fine details, just the updated silhouette of your sculpted version (not a sausage aymore),
> Back to your polygon modelling package, import the medium version, and use snap tools to build your final lowpoly ingame asset around it. Now you can optimize, use very specific topology lines and so on. UV that,
> and use it as your lowpoly to bake the highpoly too.

Regarding textures, you'd be better off avoiding the 'fingerpainting' look where strokes are placed roughly on the surface. Instead you should focus on getting a very clean bake out of Xnormal, and then use various layering techniques in photoshop to create the color variations that you want, where you want them. It is very important that this diffuse matches the normalmap perfectly. Otherwise it would look like bad makeup.

Also it is worth mentionning that normalmaps and AOmaps bake often need manual cleanup.

I might make an example model over the weekend.

Good luck!

pior

About the first 2 steps (very simple basemesh, then free sculpt, here in Mubox2 on an aging computer ...) here's a quick example :



You can already tell that the original basemesh wouldn't work properly as an ingame mesh. But it's alright, it's just a matter of recreating a proper one now. Since I have the highpoly sculpt as a reference, it would take only minutes!

Torrrtilla

Wow Pior, that's some good advise. I would really like to see how well your example would bake out with light texturing.
-Neil

Aranoth

Snader wrote:

the manes on your chesspiece lowpoly seem to be flat planes.. i assume this is what makes the NM buggy

Yes, I made two errors : making the mane flat and triangulate the model before exporting.
xNormal requires the model to be triangulated, but ZBrush doesn't seem to like it...

pior wrote:

Regarding textures, you'd be better off avoiding the 'fingerpainting' look where strokes are placed roughly on the surface. Instead you should focus on getting a very clean bake out of Xnormal, and then use various layering techniques in photoshop to create the color variations that you want, where you want them. It is very important that this diffuse matches the normalmap perfectly. Otherwise it would look like bad makeup

Should I use the AO map for the diffuse and just color it ?

pior wrote:

First off, you shouldn't make an optimized game model with very specific topology before starting on the sculpt. Instead you should focus on making a very simplistic cage giving you the maximum amount of flexibility for sculpting. If you do your 'final' lowpoly model right from the start, chances are, the silhouette of your sculpted mesh will not match it at all since you will naturally push shapes in the sculpting program - hence, a bad bake.

It totally makes sense.

And this way I can add more polygons where I need (when I subdivide the model in ZBrush, the base of the piece is too much smoothed, I think it won't happen with more polygons, defining a stronger shape).


I will try that as soon as possible, thanks for the (amazing) exemple

Aranoth

Here is my try, following your workflow :



Still not very good, the low poly mesh is not perfectly accurate and I had some difficulties unwrapping the UV for this cylinder-like mesh

pior

Hehe don't shoot yourself in the leg on the last step man! Take the time to make that ingame mesh proper, otherwise you'll always be disappointed by the bake.