Normal Map (made in Photoshop = NO HP/LP BAKING) issue, advice appreciated :)

Florent_Vilbert

Hello guys,I have encountered a problem during the NDO Detailing process of a tire I'm working on. Coz it's for work I won't be able to show you the real ingame mesh, but here is a fast example to show you the core problem.

http://image.noelshack.com/fichiers/2016/36/1473356795-circle-waviness.jpg

2 Things mandatory of the process :

- No HP / LP Baking, because not too much time to make Highpoly and preferable to do it with NDO to iterate quickly the design of the tire flank

- Uv Mapping must be like this : unwrapped as a line and not as a circle (because of Uv space available)Both of these 2 things can solve the problem I'm facing... that's the irony of it...Here is an idea that apparently could solve my problem : Subdividing

http://image.noelshack.com/fichiers/2016/36/1473356793-circle-waviness-2.jpg

As you can see, when subdivided, the shapes I drawed are not skewed... But for games, polycount is limited so here is my question :

Is there any way I could transfer/morph the UV from the SMOOTH version to the LOW one ?
Or
 Is render to texture a good option to capture the good texture applied on the SMOOTH mesh and to apply it after on the LOW version ?

Don't know a such process but maybe someone as already came through this problem...

Cheers

Eric Chadwick

The distortion is a natural side effect of mapping a trapezoid shape with a rectangular UV.

Yes, you could bake the pattern from a model, and it would apply the right kind of distortion to counteract this. In fact, you could simply apply your NDO normal map to a subdivided model, and use that as your bake target.

Edit: if you change the pattern to match the lowpoly better, you could bake a smaller map that tiles. For example, one circle per trapezoid.

Florent_Vilbert

Hmmm "In fact, you could simply apply your NDO normal map to a subdivided model, and use that as your bake target." 

That's exactly the kind of solution I was expecting... but how would you do such a thing ?

The only bakes I make are with Xnormal with a classic HP, LP and CAGE. I can't figure out how to do such a thing as my SubD Model is flat with a Normal Map...

Can you describe a little more the process you are thinking of ?

Eric Chadwick

You should be able to do this in Maya. I'm not a Maya user, but I know there is a baking tool there that lets you transfer maps from one model to another. 

Does the normal map have to be a strip that covers the full height of your texture? That's quite a bit of waste for something that could easily be tiled instead.