Nurbs stuff

Xsi
1

First off, apologies, I come from a Maya background, and as such I find myself looking for similar working methods within XSI, so just bear with me whilst I make the transgression!

  1. What is the equivalent in XSI for setting an objects smoothness, i.e. press 1,2 and 3 in Maya results in better display resolution, i think coarse, medium and high is the soft equivalents? Also, on a related note, how do I control tesselation at render time, where are my options to whack it up or down where needed?

  2. How do I add 'into' a nurbs surface within XSI, what I mean is how do I add ISOPARMS to a nurbs surface I have created, where say, the resolution is too low for what I require. An example, say I create a nurbs cylinder, which is quite long, I then decided half way down I want it to bend outover slightly, so basically, how can I add isoparms to that area. I can't seem to find any mention of this in the manuals?

Thanks.

2

"First off, apologies, I come from a Maya background, and as such I find myself looking for similar working methods within XSI, so just bear with me whilst I make the transgression! "

My recommendation is to forget NURBS as far as you can, and learn subdivision surfaces. They work much better in XSI (whereas Maya is superior with NURBS).

"1. What is the equivalent in XSI for setting an objects smoothness, i.e. press 1,2 and 3 in Maya results in better display resolution, i think coarse, medium and high is the soft equivalents? Also, on a related note, how do I control tesselation at render time, where are my options to whack it up or down where needed?"

When you have the object selected, click on the Selection button on the right panel, and click on the icon for Geometry Approximation. It should ask you whether you want to edit the property for all objects, or make a local copy. Pick whicever you want. There you can set U and V accuracy for hardware display and rendering separately.

"2. How do I add 'into' a nurbs surface within XSI, what I mean is how do I add ISOPARMS to a nurbs surface I have created, where say, the resolution is too low for what I require. An example, say I create a nurbs cylinder, which is quite long, I then decided half way down I want it to bend outover slightly, so basically, how can I add isoparms to that area. I can't seem to find any mention of this in the manuals?"

It's been ages since I last used NURBS for anything, but it went something like when you have the object selected, choose Add line or Add knot or similar from the Edit > Surface menu on the left panel (you have to press 1 to get the Modeling panel visible). Then you get a popoup window where you choose the place for the new isoparm. Once you have it in place I heartily suggest freezing the object.

3

Sorry to come into someone elses thread.
I'm curious, why forget Nurbs. Nurbs to me are more powerful as surface types. I've still yet to see a subd model that looks as good as a Nurbs model in production. Subd is new to both packages and as such, still has a long way come yet. Yeah, great, nice flowing surfaces and so on, but just try texturing the buggers for a start, something that is not even an issue with Nurbs. I also think that XSI's nurbs modelling tools are superior than Maya's, the SCM works much better than Maya's Global Stitch and fillet blends are an absolute ease with XSI and work great. Don't get me wrong, I'm a big fan of subds, check out my website (in profile) to see what I mean (although also notice the lack of textures on most of my work). But personally, I still see Nurbs as being the more powerful tool. With subd's you work on a low poly model to create your subd object, and as such your models are too perfect, too smooth in the end, whereas with nurbs you can add minute details and if errors occurs in your shape, it actually adds to the model and does not detract from it. sorry, just my tuppence worth.

4

I don't think that NURBS are a strong side of XSI. take a look at Rhino, that is what is called a landmark of NURBS modeling. at this point XSI is far behind the Rhino or Maya. I realy hope that NURBS tools will be improved in XSI v2.x

-= Barracuda =-

5

well, everybody's entitled to an opinion.

I think XSI has a couple advanced tools that Maya lacks, but the basic tools are so much worse than in Maya. Correct me if I'm wrong, but no NURBS booleans, no curve-on-surface, no curve knot-point editing (only CV editing) etc, plus IMO the Surface constraining sucks, and AFAIK these features won't be included in XSI 2 either. Those are such basic tools that I don't know how you can do everything what you want in XSI NURBS while still keeping a high productivity.

On the other hand, I haven't really run into such an object that I couldn't model (and texture) quickly using subdivs. Now I would have used NURBS for some if XSI had Maya-level NURBS tools, but now I like to use polygons rather than NURBS.

6

Thanks for the help people.

on a side note, you mentioned XSI 2 wouldn't have certain NURBS features in it, I heard Softimage was giving up Nurbs all together in favour of subds for future releases, surely that's not true, what will ILM do?
If they're not implementing key nurbs tools in XSI 2, has anything been said of future releases?

I've been a heavy subd user in Maya, and for a change wanted to learn Nurbs in XSI, they seem simple and easy to implement in there. In the manuals there's a small section about deform by surface, this looks to me fanastic for the type of stuff I create. I'm curious too on the Subd side, as even though I have messed around 'lightly' in XSi with subds, I have not as yet attempted texturing them, what's the process like, is it easy, or do you use a lot of alpha maps to get seamless texturing. I think the main thing that appealed to me about nurbs was the easy texturing pipeline.

7
  1. What is the equivalent in XSI for setting an objects smoothness, i.e. press 1,2 and 3 in Maya results in better display resolution, i think coarse, medium and high is the soft equivalents? Also, on a related note, how do I control tesselation at render time, where are my options to whack it up or down where needed?

The hotkeys for controlling tessellation will come with XSI v2.0.

To tweak the surface settings, you need to apply a "Geometry Approximation" property. If you're using NURBS, you modify the setting in the Surface tab, to alter visual display (OpenGL), modify the values in the Hardware tab. Also, you can apply a "Display" property to the surface to modify it's OpenGL displays for selection purposes (eg - have the object be shaded when selected, but wireframe when unselected). If you do not apply a Geometry Approximation or Display property to your object, then it will inherit the global Geometry Approximation and Display properties from the scene. To verify whether your objects has these properties, select the object, open an explorer view, and press "E" to isolate in the view. If a node's name is shown in italics, then it's inherited from somewhere else such as the scene defaults, a group, layer, or partition.

The display property settings can be overridden by the viewport's display properties as well independent of the object settings. So play around with them to get the effect you like.

@@2. How do I add 'into' a nurbs surface within XSI, what I mean is how do I add ISOPARMS to a nurbs surface I have created, where say, the resolution is too low for what I require. An example, say I create a nurbs cylinder, which is quite long, I then decided half way down I want it to bend outover slightly, so basically, how can I add isoparms to that area. I can't seem to find any mention of this in the manuals?

1) Select object.
2) Set selection filter on MCP to "U isoline" or "V isoline"
3) Left-clickand drag lsoline to desired location.
4) Model > [Modify] Surface > Insert Knot Curve.

Matt

Matt Lind
Animator / Technical Director
Softimage certified instructor:
Softimage|3D
Softimage|XSI
speye_21@hotmail.com

8

@@on a side note, you mentioned XSI 2 wouldn't have certain NURBS features in it, I heard Softimage was giving up Nurbs all together in favour of subds for future releases, surely that's not true, what will ILM do?

You're right, that's NOT true.

@@If they're not implementing key nurbs tools in XSI 2, has anything been said of future releases?

I'm not the official source on this, but I'm fairly sure SI has plans to eventually branch out into automotive design and other engineering industries. To penetrate those markets you need good NURBS - no ifs, ands, or buts about it. But for now, SI has to regain market share in their core sectors which is content creation for entertainment markets.

@@I've been a heavy subd user in Maya, and for a change wanted to learn Nurbs in XSI, they seem simple and easy to implement in there. In the manuals there's a small section about deform by surface, this looks to me fanastic for the type of stuff I create. I'm curious too on the Subd side, as even though I have messed around 'lightly' in XSi with subds, I have not as yet attempted texturing them, what's the process like, is it easy, or do you use a lot of alpha maps to get seamless texturing. I think the main thing that appealed to me about nurbs was the easy texturing pipeline.

The tools and process for texturing subdivision surfaces in XSI is the same as texturing polygons. Usually you apply the texture to the cage surface and let the projection/UV's propagate to the higher res surfaces. You won't get any warping. To edit a texture, select the object and use the Texture Editor by selecting it from the viewport dropdown menu.

BTW - These tools also get a dramatic boost in v2.0.

Matt

Matt Lind
Animator / Technical Director
Softimage certified instructor:
Softimage|3D
Softimage|XSI
speye_21@hotmail.com

9

Thanks a lot Matt,

your replies are both insightful and helpful at the same time.

Cheers