I have been learning to model in Blender using the subdivision modifier, cuts, and support loops. (For an example of what I mean, see this video from Arrimus 3D. I find this technique is quite good for generating smooth and interesting geometries while retaining a pretty low poly mesh to work with.
Here I have a somewhat low-poly cylinder, with two levels of Catmull-Clark subdivision modifier applied. I would like to add an extruded panel (seen in the bottom left of the picture). Do do this, I extrude out some faces and then beveled the corners with a few segments. The beveling tightens up the corners nicely, in effect forcing the sub-div modifier to interpolate over that smaller region.
I understand that this is likely the consequence of the ngon being generated in those regions. Converting to quads is tricky in this case, because the bevel has higher geometry density than the rest of the cylinder (although I am also new to this and possibly just missing the obvious solution). If I try cutting across the corner quad I seem to get different (but still visible) visual artifacts.
I realize this is a specific instance, but there are other simpler examples of what I mean. For example, consider a scenario like this: In the image above, I start with a low poly plane and then slice one of the interior quads. I extrude the sliced quad, convert its inner region to a circle, and then extrude once more. At first glance it looks ok, but the normals have some odd artifacts where the high-cut and low-cut regions intersect: The effects are less pronounced in this example.
My question is: are there some general retopology techniques or guidelines I can follow in instances like this? It seems like a relatively common thing - wanting to create a more detailed region within a low-poly mesh and avoiding artifacts at the boundaries.
You can download the blend file here if you want to take a closer look: Download (800KB)
Thanks for the assistance.