Hi John,

> Michael, I now understand what you mean about the
> fillets. I just assumed it would work similar to loops in
> polygon models (how wrong was I?)

:) Yup, it is pretty different. Fillets actually do quite a large number of calculations, including making offset surfaces (surfaces that are a constant distance away from the existing ones), and calculating the curves of intersection between 2 surfaces. Then comes some other stuff like creating fillet surfaces that follow those intersection curves, and then doing some additional extensions and intersections between the fillet surfaces and finally filling in corner pieces where different fillet pieces might meet.

Since there are a lot more complex calculations involved, there are also a lot more things that can go wrong than just pushing points around in edge loops... But the upshot is that the final result is a very accurate piece that has a cross-section of an exact circle.

You tend to get the best results if you have pretty "clean" geometry.


> I think your first method is what I am looking for. Do you think
> it's possible for me to "fake" the second lines fillet by using a
> loft?

It would probably be difficult to get good results by doing that. You could put in a "fake" piece with a loft definitely, but it will probably look pretty fake as well because is difficult to produce a smooth result with that method. The loft that you generate will not be ensured to be smooth with the adjacent surfaces. That's another big difference between working with NURBS and working with sub-d polygons - with your NURBS constructions just building 2 different surfaces adjacent to one another with any particular tool does not guarantee that they are smooth to one another. But there are a couple of particular tools like Fillet and Blend that you can use that are set up to build a result that is smooth to adjacent pieces.

The other way that you generally ensure smoothness is to build your model in larger sheets instead of in small pieces or strips when possible. You can pretty easily guarantee smoothness of a single surface construction, like one loft will be smooth inside its own generated result as long as your input curves are also smooth.

So it can help if you build what should be a smooth section as a larger surface sheet instead of trying to do it in diced up bits.

When I saw your result that had 2 surfaces that were both flat, it made me think of building one single larger surface sheet (with that loft method) there instead of that.


But just a note - it is also possible to go too far in the other direction and try to build too much out of a single surface as well. Each "larger sheet" should be a kind of logical component of the model, it can also cause problems trying to build a model made up of many different shapes out of only one single surface as well..


> or would it be possible for me to fillet in certains areas where
> the surface doesn't go flat?

That's probably possible but you would likely need to dice up the model into different pieces to make that happen.

- Michael