PDA

View Full Version : Polygon flow - avoiding smoothing problems



starbase1
01-15-2007, 03:34 PM
I really should know this by now, not sure how I have never come across it before...

I am modeling a space capsule, and started with a cylinder beveling and tapering the end to get the shape I wanted. I finally did a 'make pole' to =bring the ends to a point and avoid polygons with more than 4 sides, so I could nurbs it.

I get smoothing errors though, I suspect because I have gone from quads to triangles...

(Images attached to make things clearer.)

What's the recommended way to avoid this issue?

Nick

(And the weird surface was chosen to emphasize smoothing issues)

Surrealist.
01-15-2007, 04:15 PM
Use a poly flow like this. I have an object made up of what I call subpatch primitives. You can start here and add or remove geometry. I'd say for starters you could use less polys. Here are a few examples:

starbase1
01-16-2007, 12:08 AM
I think I get the idea - though a couple of issues spring to mind...

I'm not sure how to go about making that arrangement, and also the end object will have 15 sided symmetry (not my design) and I think it good to try and keep that at a low level...

Nick

rexhiebert
01-16-2007, 07:32 AM
Use Fix Poles. The help docs actually have examples of the same thing. Fix Poles adds a little more geometry to resolve the issue.

starbase1
01-16-2007, 12:09 PM
Interesting - I tried Fix Poles, and it made it a bit better, but did not fix the problem:

Surrealist.
01-16-2007, 12:49 PM
Fix poles I was aware of but I bagged that idea when working this idea some time ago. The answer is in a simple polyflow and for the best results, just do it by hand. If you look at those examples I gave it should give you an idea of how you'd have to set it up.

The way I calulate it is that I count the sides of the tube. If it is 24, I have to have geometry that terminates in 24 points at the tip. Well, for a simple object like this, that's too many. But if you simply must, then you have to have a 6X6 box mesh at the end. So make a box divided by six, center it at the tip of the tube, delete the tip polygons and then reconect the sides to the outer points on the box mesh by creating 24 polygons around the edges that connect to the boxes. A lot of work. But you don't need that many.

Thants why I created my tube with 8 sides so it only needed to connect to a 4x4 box mesh at the end.

And of course this is only one way to skin it. There are many other methods. But keep your ploly count low and simple.

I keep this object full of layers handy so when I need a primitive shape for subpatch I have it.

But you can also do pretty good with catmul clark if you have LW9 and not have to worry about ngons.

Surrealist.
01-16-2007, 01:03 PM
Catmull-Clark in action.

starbase1
01-16-2007, 01:35 PM
Thanks Surrealist, I appreciate it! The Catmull Clark looks like its worth a shot...

The current 'model' was just a dummy run to get it roughly right and identify any problems, (such as poly flow!) before I do it in anger.

The 15 sided bit is really weird, not my design. It will basically end up with 5 legs each attached to 3 segments.

Nick

Surrealist.
01-16-2007, 03:18 PM
Oh, OK good. Yea if you need that many. Anyway these ideas will get you rolling in the right direction.