N-gons for High Poly baking??

Amank679

Hi guys,

I'm in the process of baking my high poly detail, with Substance Painter, but  I'm confused about the use of polygons. I've read threads where having ngns can cause issues with baking, (Specifically with xnormal) but I've also heard the argument that since polygon count doesn't make much difference for high poly baking (as it will convert to normals later) that ngons would not cause any issues.

I'm now confused as which to believe, please let me know our thoughts.

Thanks in advance!

FourtyNights

N-gon may be an useful type of a polygon with subdivision surface modeling techniques, mostly when creating hard surface assets. Any n-gons on the unsubdived cage mesh of the high poly model will always turn into quads when subdivided, so the issue of having n-gons is solved automatically.

N-gons in the low poly model are bad. It's better to have low poly models made from the combination of quads and trianlges only. When you've finalized your low poly model, you're going to completely triangulate it anyway before baking. Also automatic solutions for triangulating n-gons are usually bad, so it's best to manually connect some edges inside an n-gon to form quads and triangles. Because automatic algorithm of triangulation may produce triangles too thin, or other badly shading results.

sprunghunt

If you have N-gons in your low poly model that will cause problems. The Substance tools do not read n-gons properly for the lowpoly. 

But N-gons in your hipoly aren't a big deal. 

On the other hand how hard is it to just triangulate those faces on your model before you export it? if you're using maya you can just run 'cleanup mesh' on the model with 'fix problems' turned on. Most programs have some way to select n-gons and triangulate them. 

musashidan

From what I understand from your post you're more concerned about n-gons in the highpoly than the low? N-gons are 100% fine for your high poly. In fact, they are actually an essential part of my workflow. As mentioned all tris/quads are quadified when sub-divided. The sole purpose of your high poly is to bake its smoothing/details to the low. The only thing that matters is that it matches the low closely(silhouette) and that the surface shading looks good. That's it.

Amank679

FourtyNights  Thanks for the reply, that's what I was thinking, but the clarification helps!

Amank679

musashidan  Thanks for your reply! I do understand that low poly assets can't have Ngons but the clarification helps on the high, just the answer I was looking for, thanks!

EarthQuake

To clear things up a bit, when people talk about ngons in high poly, they generally mean ngons in the cage mesh for sub-ds. In this case ngons (and tris) and perfectly fine and will split into quads when you freeze the sub-d and export.

If you have ngons in you highpoly mesh that you intend to export to another app, this can be problematic, as some apps do not handle ngons at all or will not handle them as well as your 3D app. In this case it's generally best to convert to quads at or before export.

For low poly objects, you should convert these to triangles before exporting to an app to bake normal maps or to your game engine of choice. If you use quads or ngons to bake, another app or engine may triangulate it differently, which will give errors in the normal map.