I want to start a discussion about an important aspect of surfacing: patch layouts.
This seems to always raise varied opinions, as it should, and it is a topic that I personally feel fuzzy about. Fuzzy being a nice way of saying... absolutely stumped.
When are patch layouts beneficial, and why?
When do patch layouts become a nuisance?
I think it is heavily dependant on the model at hand, and the construction techniques for that particular model to get from start to finish.
Somehow though, when I see a big surface with not a lot of topology, it just feels...wrong. I want the rounded off bits to be separate surfaces curvature continuos, I want the straight bits to be the simplest geometrically as they can be to represent the shape it needs to be. I do not want this big mental surface pulling all the weight! What is wrong with me though? Because by the same token, all I feel I am doing is getting more boundaries and in turn more discontinuities to worry about!
To sum up a few pros and cons, the way I see it (do not know if I am right about these) on patch layouts:
Pros
- Simpler, but multiple surfaces mean less tension on the surfaces resulting in less pinches, bumps, inflections or dimples.
- Makes editing the model easier and more cordoned off, making a G2 round bigger will not disturb the rest of the model.
- Aids the construction of a model by providing more framework to work with, during curve and especially surface creation.
Cons
- More surfaces means more boundary edges, which in turn means harder to maintain continuity.
- Seems like it only really starts to become highly beneficial in high end class-a surfacing for auto or aero with higher order surfaces.
Anybody else feel the dilemma sometimes?
We could get some insightful dialogue going
If I can do it in one surface, I will.
I think my big caveat for that is if the surface is made of open or closed loops. That will make a big difference, as building off of those it is easier if they are all open or all closed. So if you are modeling a tube (like a handle, or an aero wing, etc), then it is important to decide if each rib is a closed loop, or 2+ open edges.
The only time I can think of when I will purposefully add new patches is when the surface changes direction over 90° from the normal of the existing surface. Once that happens there are bound to be issues somewhere, and it is best to make it multiple surfaces. Also, the obvious abrupt changes in curvature or non-curvy shapes.