Attempting Nurbs Again

[DaJuice]

Alright, I think I need some help here. Please someone show me the error of my ways.

I'm planning to model a keyboard... actually, I'd be happy with a filleted box right now. Yeah, I am serious. I can't seem to model a filleted box with NURBS.

I am building the fillets manually (time-consuming, but there is no automated way of reliably getting fillets across multiple edges). So I've got my fillets built... the problem is when I try to join the seperate parts of the model as one to get rid of the seems. How do I do that when 9 times out of 10 the U and V coordinates don't match up and I get messed up surfaces? I have to mess around with Reverse SOPs and it's always hit or miss, and if do manage to get two surfaces stitched together I get stuck again when I try to join the result to some other surfaces. It's like a rubik's cube!

I thought about converting to polys and consolidating points, but the resultant points between different NURBS surfaces don't match up. There goes that idea.

There must be something I haven't figured out. Either that or the NURBS tools cannot actually be used to model anything remotely complex. Most of the time I would bet on my ignorance. Prove me right!

Found a pic of what I'm trying to get and attached it just to be clear.

Thanks!

[sibarrick]

Do you mean that you are trying to join all the patches together to make one NURBs surface? That isn't possible with NURBs you have to keep them seperate. A NURBs surface has to be regular rows and columns and a filleted cube just ain't goner work that way.

If you have to have a single mesh try use a box and polybevel sop with all the edges selected and high density round in the bevel type.

[digitallysane]

The rounded box in your image should be done with the Round SOP, but it would generate trimmed NURBS, not a continuous surface (which is not possible). Look at the help page for the round SOP, there is an example there.

Dragos

[DaJuice]

Thanks digitallysane, but it seems like a box is about the only thing the Round SOP will fillet reliably.

OK, so if I understand correctly when you're modeling with NURBS in Houdini you generally don't join your surfaces.. is that correct? Unless the model is n x n rows, but most objects can't be modeled that way (or at least would be highly undesirable to model that way).

btw, when I said join, I was basically looking for join like in Rhino. I realize now it's not the same as when Houdini joins surfaces. Rhino does not generate a new continous surface, but rather makes it so the joined patches match up perfectly at the edges and then sort of groups them together.

[sibarrick]

Well doing a fillet should make the surface join perfectly, maybe it's a precision thing, Rhino works at 16 bit precise whilst Houdini only works at 8 bit precision. Do you have a render or file that shows the surfaces not joining properly?

[DaJuice]

No, I guess it should be fine. I don't think I will use NURBS for this though. There is not enough precision and it's too time consuming to build the surfaces.

Thanks guys.

[digitallysane]

OK, so if I understand correctly when you're modeling with NURBS in Houdini you generally don't join your surfaces.. is that correct?

You generally don't join NURBS in a continuous surface (as you do with polygons). Even Rhino does not do that, it just treats a group of surfaces like an entity (it's more CAD-like in its approach). A NURBS surface is a deformed m x n grid. That's all.

Check the Join SOP, Stitch SOP, Fillet SOP, Project, Trim, Bridge, Profile.

Somewhere in the help there is a nice explanation of geometry types.

Unless the model is n x n rows, but most objects can't be modeled that way (or at least would be highly undesirable to model that way).

That's why subdivs are so popular...

Dragos