How to smooth trim edge

[hexxi24]

i always guess how to smooth the trim edges , for example to use nurbs trim tools to create the front light of my nurbs car model , but once i use the trim tools to create the hole of
the nurbs surface the trim edge would cause ugly alias, could some one give me some advise hot to fix this problem?
or they just use patch model to reate the hole of the fromt ight of my car model . thank you very much

[jtk77]

trims are evil .
But one way to smooth a trim is to add mroe poitns to the curve that is making that area invisable . beocuse of course, trims have no edges , only an area that the rneder seems as clear. The gemotry still exsists.

So , mroe complex ..smoother curve used for your trim and it will be smoother.

............GO AWAY..THERE IS NO WIZARD HERE!..............

[mike-heintzman]

always an annoying part of maya this is - funny thing is it's trims still look crap when exported to other packages - they are a mess. Technically a global trim step value should fix the value - or raising the step / res of your starting curve AND surface.

• Non smokers die every day.

[rhonedog]

knocks on your front door during dinner

"Good afternoon Sir. My name is Mike and I am going door to door asking people just like yourself if you have ever considered the benifits of polygonal modeling. You'll never have to deal with nasty trimmed sufaces again, and you'll be a smash hit at parties. If after 1 week you arent completely satisfied, feel free to return your polygons to us along with a notorized and signed fax of your ass just so we know that you are no longer interested in our product. I hope you have a wonderful day sir, and I thank you for your time."

Mike R

Insert non-witty signature here

[jtk77]

In reply to:
knocks on your front door during dinner

"Good afternoon Sir. My name is Mike and I am going door to door asking people just like yourself if you have ever considered the benifits of polygonal modeling. You'll never have to deal with nasty trimmed sufaces again, and you'll be a smash hit at parties. If after 1 week you arent completely satisfied, feel free to return your polygons to us along with a notorized and signed fax of your ass just so we know that you are no longer interested in our product. I hope you have a wonderful day sir, and I thank you for your time."

Mike R**Insert non-witty signature here**

hahah!

............GO AWAY..THERE IS NO WIZARD HERE!..............

[mike-heintzman]

read the fine print on that agreement -

• slow as shitt

• texture like shitt

• bad for cad.(like shitt)

• Non smokers die every day.

[perseus2]

The answer here is tesselation, if I understand your question correctly. While it's very difficult to get great results, good ones are not impossible. Here's a few suggestions:

Wherever possible, rebuild. I don't mean the auto-rebuild surface tool, I mean use the trim, the fillet or the intersect tool to define your curves, then use birail, square or other tools to create non-trimmed surfaces.

If that's impossible, turn on the hardware shaded mode and display the render tesselation in your attribute editor. There, adjust the values so that the tesselation matches as closely as possible. Remember, the key here is that the triangles line up with each other, not that you have more triangles. Sometimes fewer are better. Often, I have not had to turn on the advanced tesselation options; I've gotten good results with just the curvature tolerance and the U and V divisions factors. Get to know what all the tesselation attributes mean, and resist the temptation to just crank them all up and hope for the best.

Finally, I think you can get better results if you build your object large and scale it down after the trim. Although I haven't really "formally" investigated this, I think it has something to do with how accurately Maya is able to calculate larger radii on fillets.

Hope this helps - I've been wrestling with the same problem. If anyone else has any suggestions, I would really love to hear them.

In reply to:
i always guess how to smooth the trim edges , for example to use nurbs trim tools to create the front light of my nurbs car model , but once i use the trim tools to create the hole of
the nurbs surface the trim edge would cause ugly alias, could some one give me some advise hot to fix this problem?
or they just use patch model to reate the hole of the fromt ight of my car model . thank you very much

[rhonedog]

@@read the fine print on that agreement -
@@- slow as shitt

I've never noticed it. My nurbs models always act heavier when I work with them. Once you start stitching Nurbs surfaces to make them seamless THEN tell me which is heavier. ;o)

@@- texture like shitt

Until you get fast at it. I'de perfer to spend my time tweaking UV's then trying to stitch seams. Throw in a tool like deep paint 3d, and texturing becomes a breeze.

@@- bad for cad.(like shitt)

Cad? Like Autocad? I dont know a thing about autocad. Want to talk about politics instead? I live in a drawer. I dont understand.. ~~fritz frtiz~~

File Corrupted

@@- Non smokers die every day.

When smokers die, they have a way more impressive dying "I was always proud of you, son" death wheeze.

Mike R

Insert non-witty signature here

[joojaa]

Maya behaves quite badly with trimmrd surfaces, baceuse you will get lots of unneccesery history using them (if you need better render tesselation set the smooth edge on). now theres nothing bad in this if you intend to refresh your surface once ina millenium but if you intend to animate it then, avoid theese surfs as hell.

But 3D CAD (we are not talking about autocad its a 2d cad you know) software on the otherhand do this quite well. So if you import a IGES from any 3d CAD you will get a lot of trimmed surfaces.

But on the otherhad 3d CAD software like PRO/E do offer some benefits: Better rounds (you can make a cube a ball by rounding i pro/e without failure), Better boleans, more presicion (after all film quality microtesselation is nothing compared to what the NC machines get as imput, the newer ones can even use nurbs directly = ~unlimited tesselation). On the otherhand they have worse moddeling tools for organic stuff (but not much), but hey its a modeller (without much rendering) capability that costs about the same as maya.

[perseus2]

In reply to:

if you need better render tesselation set the smooth edge on)

Be careful using smooth edge; it tesselates the edges more than the surface area - theoretically that's what you want, but if you're using a shader like Blinn or Phong, the highlight compresses when it hits the smooth edge.

[joojaa]

In reply to:
but if you're using a shader like Blinn or Phong, the highlight compresses when it hits the smooth edge.

Are you sure, because i know this will happen to surfaces with goraud shading (so it affects hardware views mostly), atleast its more pronounced that way. But am not sure that phong will get thiskind of problems, gotta check it out, but its totaly possible, if the surface suddenly changes direction (as highlight is interpolated from the points).

Anyways its hellof a lot better to have clean edges than a slightly compressed highlight.

Also the trimmed edge would get this kind of problems anyway so theres not much you can do, as the tesselation would break slightly anyways.

But if it causes unacceptable visual problems then you just have to use uniform tesselation (which ican be expenssive). But youd still have some problems with non uniform tesselation.

[withnail]

i have read all of your posts and really learn lot , but it seems
have not a good method the keep trim edge smooth. or just do not use trim tool ? just use patch model . or just use studio tools or other software once want to create a good relastic car model i all just my opinion

[ricedragonls96]

Dear Rawhedrex,

Am I totally missing something here? since when have NURBS been easier the texture than polys? Do you have any idea how easy it is to layout UV's?

As for which of the two is heavier, Did you know that Maya HAS TO convert NURBS to SUPER HEAVY Polys in order to render them? It has been argued that other rendering packages can render nurbs, but that's not the point.
You claim that polygons are "Slow as sh*#" If this is the case, then why don't videogames use NURBS instead of those "slow" polys?

Each has their ups and downs, but you don't seem to know either.

[joojaa]

In reply to:
Am I totally missing something here? since when have NURBS been easier the texture than polys? Do you have any idea how easy it is to layout UV's?

Sometimes its easier to use nurbs surfaces when texturing especially if you have a deecent 3d paint package available. The reason for this is quite simple, you must plan your surfaces carefully if you intend to use nurbs. Also nurbs surfaces get uniformly mapped.

But i dont think this is a major issue at all.

Laying out uvs can cause much unvantted problems, but most of the time its fine.

In reply to:
As for which of the two is heavier, Did you know that Maya HAS TO convert NURBS to SUPER HEAVY Polys.

Not realy, its all up to how you do the tesselation and patching up. But sice nurbs surfaces are usually used when you need those super high ress surfaces then its ok.

Yeah and about polys, games eingenes use a quite finite number of polys and rendering polys is pretty fast (thats why most renderers use polys you know). But as your polycount rises so does the prformance overhead. Nurbs on the otherhand allow for fast working speed without needing to worry about the presicion.

But i thik subds (or something even bertter) will eventually prevail, and in the future (as subd tools evolve), even mechanical eingeneers are going to start using subds. But nurbs arent going to dissapear in the near future.

Allso a note on micropoly tesselation (This is how renderman, and some other apps do it), wich is technicaly tesseleation after all. Im not sure but i think that micropoly tesselation is quite expensive. But there is some point at wich the mircopoly tesseleation will be better than using standard tesselation.