# How to connect a circle to a grid with even topology?

I'm trying to connect the pieces shown below together seamlessly, but I can't figure out the correct way to do it.

I have tried a bit of everything, but nothing seems to give me the result I'm looking for. The face density should look even and there shouldn't be any odd geometry. Below is how I've managed to make it. However, I'm really unhappy with the result as there are ugly tris that stick out - they affect shading, among other things.

How would one go about this? I've been trying to figure it out for far too long now.

EDIT:

How would I do this as illustrated by an answer below? Because of a higher polygon density I can't do this by hand everywhere as it simply isn't efficient.

My mesh is rounded as shown below. Think of it as being a part of a sphere.

• Commented May 29, 2018 at 18:31
• Unfortunately I can't use this method as my model is rounded. Commented May 29, 2018 at 18:43

You are merging 2 meshes with very different densities. The circle is about double the subdivision compared to the rest. Your topology should look similar to this:

• the 5 green polys (the E pole vertex in the middle) are responsible for the change in edge flow
• both marked edgeloops should be nice and even to produce edges with consistent curvature alongside them

The goal is to use control mesh with the least amount of 3 or 5 edged vertices. Topology like that minimizes any surface artifacts (shows mostly on reflections)

I got this piece by using Shrinkwrap Modifier and projecting the geometry onto a subdivided cylinder.

To project 2 circles with Shrinkwrap onto a sphere is bit trickier, because we get this overlap, that has to be cleaned:

It's more elegant to prepare both pieces beforehand, so they line up together nicely when projected (the math of projecting onto sphere is not that complicated here). We cut each piece with an ellipse that has same width as the sphere, but has the minor axis of √2/2 (about 0.707):

I used the ellipse just as a guide to move and align vertices, but you can use Booleans to be exact.

Now it's easy to join the meshes perfectly:

If this is a mesh not to be sub-surfed, but a high-density game model, you can proceed the same way with a lower-poly control mesh and then apply the subsurface modifier at a level you like.

High-poly meshes are easy to sculpt or generate procedurally, but pain to model with precision.

If you keep a mesh with same size polygons, the smooth shading on it will also produce nice results, long triangles or long polygons do not behave nice. Your mesh from your question is very close to that state, with some cleanup I would call it fine. If you decide to use a normal map baked from the subsurfed high-poly, then even this stops being a problem, because the normals are now defined in a texture and you can have a mesh that looks however you like. The only concern becomes to have enough geometry so the silhouette looks clean.

• Thank you, this is exactly what I was looking for! How did you achieve that topology? It doesn't look handmade. I'm wondering if I could apply the method to a spherical piece. i.imgur.com/Rpf4kei.png Commented May 29, 2018 at 15:41
• @Michael I just extruded a circle couple times, modified the left part by hand (area around green faces) and then used shrinkwrap modifier to project it onto a subdivided cylinder to show the topology works also on curved surface. Commented May 29, 2018 at 15:56
• I understand the end result and partly your explanation but I don't know how to replicate it, especially since you did it by hand. I also have a bigger polygon density. Could you include a step by step explanation with pictures preferrably? Commented May 29, 2018 at 17:01
• @Michael It's best to keep the mesh simple if possible, your mesh is very dense. Is there a reason for this? If not, I'll make the example with clean simpler mesh and I will demonstrate this on a sphere. It will work on dense mesh too, but it's more work and not so elegant. Commented May 29, 2018 at 19:39
• @Michael Nothing special, G to move vertex, E to extrude vertex, X to delete vertex, F to make edge or face, etc. The knife tool K might be also useful. There are good video tutorials for editing meshes if you are interested - like modeling this face Commented May 30, 2018 at 13:45