Baking a tube

pes

Hey guys. I always have a problem setting up a tube-like objects for baking a normal map.  Like a sleeve end for example. When I need to make a really low poly mesh.
How do you set up the lowpoly mesh to bake the tube? To get as little artefacts and stretches as possible.

musashidan

If you're talking about waviness in the baked map then it is unavoidable on such low-poly curving/cylindrical geo. The normal map can only do so much when baking from a sub-D.

If you can afford a unique bake then you can afford a few more segments. You can always terminate the extra edgeloops a span or 2 down to cut down on geo. It won't be as prevalent as the end of the tube silhouette.

Obscura

Hi. It not really possible to get a normalmap without wavyness with such lowpoly cylinder. But there are some workarounds. This is what I do in the cases when its possible to apply it:
Make the lowpoly, and duplicate it. Instead of adding support loops and subdivision modifier, use chamfers so the circular segmentation stays the same as the lowpoly. In this example I made it more drastical, more lowpoly than yours so it clearly shows how it works. This is the highpoly and lowpoly mesh:

And this is the resulting normalmap without errors:

This is how it looks when applied on the lowpoly:


Hope this helps.

huffer

You can also add a support loop on the low poly, right over the inset, bake with it, then remove it for the final low-poly mesh - it will hold the cage better and get rid of some waviness.

Obscura

Thats a not so good practice because of multiple reasons, even though it could possibly work in some rare cases, but it would usually lead to other artifacts. First of all, the shading of the lowpoly (vertex normals) is taken into account when the normal map is baked. This is why sometimes you see triangulation lines or "bumps" in the normal map when the mesh is low poly. So altering the shading and the triangulation of the lowpoly after the bake would most likely result errors. Second thing, also connected to the first one, normally you want to make sure that the triangulation is the same before and after baking because if it changes, you would get x shaped shading errors when the normal map is applied. The top side of the cylinder would also bake badly.

I did the same test with the suggestion above, these are the results:
Subdiv highpoly, and lowpoly mesh with supportloops added

This is how the bake result looks when its applied on the supportloop lowpoly. Its ok but the wavyness didn't go away and as I pointed out, the top part bakes very bad:

Same normalmap applied to the lowpoly without supportloops. Things goes worse as its expected:

Baked normal map:


Things were baked in Substance Designer in both tests.

huffer

I think it depends, the loop helps a lot with the waviness, from horrible all-round to usable (but still present). You can get better results depending on the loop placement (too close to the edge and you get artifacts like yours since it affects the edge bake). Triangulation shouldn't matter since there are hard edges and shading doesn't change once the loop is removed.

Obscura

The cap still has a lot of artifacts right?

huffer

Cap won't have artifacts unless the loop is too close to the edge - in that case not only you'll get them after removing the loop, but also because it affects cage projection on this the edge. So there is some planning involved, but it's the easy and fast (you can store the loops in an Edit Poly) if you can't add more segments to avoid the problem entirely.

Obscura

I meant that it shows circle normal but angular silhouette, so it makes the faking very obvious - and kinda bad looking in my personal opinion, but everybody can have their preferences. The method I was showing would give "better" results on the cap, again in my opinion, because the shape is matching.

huffer

Ah I understand, I was focusing only on the waviness of horizontal details and edge bevels. Then indeed your method is the solution to avoid those entirely.  I for one have no problems with the faking, I think with a lot of angles it reads as round well enough.