Sliver Triangles and Normal map

garrettia

Good evening. What is the reason why the long thin(sliver) triangles are causing problems in the normal map? Can you recommend a source that I can learn from?

Fabi_G

Hi! Best add an image showing your problem, else it's hard to understand what you mean exactly.
You could learn all sorts of things from the wiki. It also contains some links to informative forum threads.

garrettia

This isn't a problem I'm having at the moment, but to Eric Chadwick's question https://polycount.com/discussion/comment/2213096#Comment_2213096 at this link "Long thin triangles are generally bad. For normal mapping, but also for rendering in general. The few extra vertices help avoid those long thin tris." I saw Eric write this answer. And I've come across a few other places where people are saying that long thin triangles cause issues with shading and normal mapping. I wonder why why long thin triangles are causing these issues if I could find an article or a resource on this topic it would be great.

garrettia

So what I'm actually wondering is why shading is broken in thin triangles.

EarthQuake

There are a couple of issues here. Firstly, long, thin triangles are inefficient for the GPU to render, so it's generally best to avoid them where you can.

Secondly, long, thin triangles (or short and thin triangles) may be represented with a very small area (sub-pixel) in the UV map. So when the normal map is baked, there may not be enough resolution to properly represent the geometry. This will cause shading artifacts.

garrettia

thank you so much @EarthQuake