Problem with exporting normals from Zbrush

WusikiJeronii

Hey there. Now I'm getting my first experience with character creating. I've made a sculpt of character's head. I tried bake normals and I found out a few problems. 



Why artifacts appear? What's wrong?

musashidan

Firstly, Zbrush is one of the last options I'd use to bake. There are so many other quality options available so why would you want to?

Secondly, I understand your excitement to run through the pipeline, but if you're serious about creating character sculpts in Zbrush then you have a long, long way to go until that head is anywhere close to resembling believable anatomy. I'm not trying to be a dick. You'll thank me in the long run. Tertiary detail should be far from your thoughts. Spraying random noise on the face is not tertiary detail.

On to your problem. It looks like the rays are intersecting as they are being projected on the lid/brow. Lower the projection distance and bake fully averaged. Also, I'm betting that your UVs are badly distorted judging by your layout. You should break the nostril/mouthbag away to their own islands.

WusikiJeronii

Thanks for your help. Yeah, zbrush is very bad software for tex baking. I've moved my mesh to Cinema 4D, then I've baked normals and got a correct result. Thanks. Now I'll try to improve my sculpt.

sprunghunt

Zbrush doesn't have normals. There are no normals on a zbrush model. If you look at a low resolution model in zbrush's viewport you'll see that it's faceted. 

Altea

They mean normal maps, that zbrush can generate but not display

musashidan

sprunghunt said:

Zbrush doesn't have normals. There are no normals on a zbrush model. If you look at a low resolution model in zbrush's viewport you'll see that it's faceted. 

Of course ZB has normals. A vertex/face can't exist without normals. What Zbrush doesn't have is smooth shading - well it actually has a hack to force a quasi-smooth shading mode - at least not in the sense that tradtional DCC has.

WusikiJeronii

What is the day today? Either I just don't know English well, or I get answers unconnected with each other all today's day. 
And about normals - theoretically, polygons can be without normals, but then the polygon doesn't be illuminated and viewport doesn't display that. However soft for polygonal modeling will see point and edges of the polygon.

sprunghunt

musashidan said:

sprunghunt said:

Zbrush doesn't have normals. There are no normals on a zbrush model. If you look at a low resolution model in zbrush's viewport you'll see that it's faceted. 

Of course ZB has normals. A vertex/face can't exist without normals. What Zbrush doesn't have is smooth shading - well it actually has a hack to force a quasi-smooth shading mode - at least not in the sense that tradtional DCC has.

You can render a polygon without normals. You just don't do a backface calculation. Or any kind of shading. 

But the precise answer would be that zbrush doesn't save normals as part of a file. It calculates them when it goes to draw a model. A lot of the things that apply to normal 3d programs don't apply in zbrush. 

WusikiJeronii

sprunghunt said:

musashidan said:

sprunghunt said:

Zbrush doesn't have normals. There are no normals on a zbrush model. If you look at a low resolution model in zbrush's viewport you'll see that it's faceted. 

Of course ZB has normals. A vertex/face can't exist without normals. What Zbrush doesn't have is smooth shading - well it actually has a hack to force a quasi-smooth shading mode - at least not in the sense that tradtional DCC has.

You can render a polygon without normals. You just don't do a backface calculation. Or any kind of shading. 

How??? Normals are part of rendering model. How can the viewport ignore the lighting model?

Altea

Is normal this?

sprunghunt

WusikiJeronii said:

sprunghunt said:

musashidan said:

sprunghunt said:

Zbrush doesn't have normals. There are no normals on a zbrush model. If you look at a low resolution model in zbrush's viewport you'll see that it's faceted. 

Of course ZB has normals. A vertex/face can't exist without normals. What Zbrush doesn't have is smooth shading - well it actually has a hack to force a quasi-smooth shading mode - at least not in the sense that tradtional DCC has.

You can render a polygon without normals. You just don't do a backface calculation. Or any kind of shading. 

How??? Normals are part of rendering model. How can the viewport ignore lighting model?

yes - you ignore the lighting model. You write your engine to render everything from a flat shaded perspective. Or you generate a normal per-object instead of per-poly or per-vertex - by assuming everything is a sphere and then shading things based off their bounding box.

WusikiJeronii

Mmm. Thanks

musashidan

This thread certainly got a bit strange. Why are we talking about custom-written render engines and invisible meshes that have no normals? For all intents and purposes Zbrush geometry does have normals. It doesn't matter what happens if a renderer renders a hidden mesh. What we're concerned about is normal map baking. And in this regard vertex/face normals that WE can see.

sprunghunt

musashidan said:

This thread certainly got a bit strange. Why are we talking about custom-written render engines and invisible meshes that have no normals? For all intents and purposes Zbrush geometry does have normals. It doesn't matter what happens if a renderer renders a hidden mesh. What we're concerned about is normal map baking. And in this regard vertex/face normals that WE can see.

Zbrush geometry *visibly* has no vertex normals. And there's no way to edit the face normals in zbrush.  

So for the purpose of normal map baking a zbrush model isn't useful unless it's the hipoly model. This means that using the baker inside zbrush - which uses the lowpoly from zbrush - isn't a good idea at all. 

I'm trying to help people understand the theory behind these decisions. *Why* zbrush doesn't work as a baker. Good fundamental knowledge helps you be better as a game artist.

musashidan

@sprunghunt fair enough, mate. I'm all in favour of trying to help beginners understand the why. I'm not a tech artist or a programmer so I didn't know the theory of what was behind the reason Zbrush behaves this way. I do know that the canvas document shading was to enable us to work on very high res meshes back when ZB first came out(I've been using it since V1.5)

I did open my first post by advising OP not to bake in ZB. Perhaps I should have explained my reasoning based on my own experiences.