Avoiding ngons when sculpting


I’m a beginner when it comes to 3D modeling. I didn’t find a ‘sculpting’ category in the forums, but I think sculpting is actually a subcategory under modeling.

So, I hear ngons and triangles are bad. Fair enough. And I’ve been watching this tutorial to learn some sculpting in Blender:

I notice a few issues here. First, I see that he starts with a quad based sphere, which is seen as the correct way. But as soon as he starts deforming it, I see that these quads are no longer flat, and are being triangulated arbitrarily. Isn’t that bad? Now you have no control of how it’s being displayed do you? You can see it particularly at 8:28 and 9:36:

Then he goes on to explain a concept called dynamic topology, where you can add detail only those places where you need it. It’s at 11:49, but I can’t put a direct link because new users can only put two links in a post.

I can not see how this can be done without introducing ngons…, the quad next to a subdivided quad would have to be an ngon, but these are supposedly bad and should be avoided.

So what are the best practices to deal with this? Do you simply disregard the rules about no ngons when doing sculpting, or do you avoid using the dynamic topology, and instead start with a really high polygon count to begin with? Or do you use triangles, even if they are to be avoided for other types of modeling, to avoid the arbitrary triangulation we see in the beginning of the video?

Just one extra note on the post above: It looks like I’m posting the same link twice, but the second one is actually a direct link to a location in the video, so you can click it to immediately see what I am talking about.

There’s a lot to say here, it’s a big discussion going back ages. I’ll just add that dynotopo does NOT create ngons. Whenever you use dynotopo, it triangulates any necessary quads.

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OK, I believe that. However, I understood it the way that triangles were also to be avoided. But thanks for the clarification!

So, I’ve been experimenting a bit with at, and watching tutorials. I see that Blender’s sculpting template, the one you get when starting the program and selecting ‘scultping’ for your startup template instead of ‘general’, consists of a fairly high poly-count sphere which has only quads. Turns out you can make one such sphere by making a cube, subdivide it and apply. It won’t be perfectly spherical, but that’s not necessary for sculpting organic shapes anyway.

After experimenting it seems like dynotopo converts everything to triangles. Looking at various tutorials out there it seems like working with triangles, and a really high polygon count is considered acceptable practice for sculpting, even though for other types of 3D modeling people advice against this.

Also, a word that frequently comes up is “retopologize”, so it seems we are not supposed to keep this high poly count and all these triangles in the final product, but instead retopologize at the end. So, I guess I have to learn more about this subject: Retopology.

Please correct me if any of my observations so far are wrong… :slight_smile:

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You are correct! Sculpting will result in super high poly meshes that are not well optimized. Retopologizing allows you to get back to a good quad flow. You can bake the high poly mesh to the quad flow mesh to preserve details.

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