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View Full Version : Where to place Tri's in subd vehicle modelling.



dx394b
05-30-2007, 06:52 PM
I have been having difficulity creating features such as square intakes/headlight recesses or sharp accents especially on the front bumper areas of any vehicle I attempt to model. When using the "keep everything a quad" technique I find that no matter how I bandsaw and finess the polyflow to minimize unwanted seams I always end up with creases in unwanted places.

I have seen many fine vehicle models on these forums that seem to use 3 sided faces judiciously to create enough local detail for sharp corners without having unwanted edge loops throughout the model.

How are they able to place those strategic triangles so that they do not pinch and crease the surface?

Until I master such techniques I feel like I will always be stuck in my learning process.

I would be grateful for any comments and assistance that may help.
I will provide visual examples of my problem shortly.

Thanks

Mattoo
05-30-2007, 09:42 PM
I've been doing this crap for way too long and whenever I have to do this it's a different solution every time.
I usually play with it a bit, I haven't found any particular rules that fit all situations - you eventually get a gut feeling for it but even then you can get stuck and hack away at it for a while.

The important thing to remember is that often these things (pinching) look a lot worse in your OpenGL viewport than they do in final render. The renderer is much kinder to triangles and n-gons than OGL.

And the keeping all quads thing is good practice but I wouldn't go nuts trying to get that unless the surface is to be deformed.

colkai
05-31-2007, 01:46 AM
If you don't already have it, I'd heartily recommend buying the Kurv SSR car modelling DVD set, that will really help give you an insight into the process.

Extent
05-31-2007, 02:41 AM
Just to echo Mattoo, make sure you check in layout. I found that if you freeze the object in Modeler that it looks a lot closer to the final render shading than it does in subD mode, so if I'm working on a tricky seam I do a lot of <ctrl>+d, <ctrl>+z to check without having to render the thing.

You could also give CCs a try.

dx394b
06-01-2007, 11:52 PM
Thankyou for the advice. In a way I am relieved that there isnt some trick or technique that I was missing (Though checking the shading in various other ways will be very usefull.)

As it is just simply a matter of hard work, then I'll have to keep at it untill I develope more of an eye for those areas.

Perhaps placing tri's on the nearest semi flat area?

In any case, I am a new LW user and have appreciated the warm welcome.

I look foward to seeing more of everyones awesome work.

dx394b
06-01-2007, 11:58 PM
Almost forgot- I'm planning on getting Kurvs Dvd set when I'm able. They look great.

Ah. .so much to learn, so little time.

colkai
06-02-2007, 04:41 AM
Almost forgot- I'm planning on getting Kurvs Dvd set when I'm able. They look great.
You won't regret it, they were very informative for me. :)


Ah. .so much to learn, so little time.
Ain't it the truth? Never stop learning, always something new to occupy the ole grey matter. ;)

hrgiger
06-02-2007, 05:59 AM
Well actually, there is a trick to using tris in a subD model. The whole secret is placement. Once you have been modeling for a while and do a fair amount of experimentation, you'll learn where you can get away with tris and where you can't. As Mattoo said, what looks bad in an OGL display, may not be all that prominent at render time.
Don't let anyone say that the only way to model is with all quads, don't limit yourself like that. Tris are very useful, but you have to use them with the understanding of how they are going to affect the shape of the model.
And I would also highly recommend the Kurv dvd's on vehicle modeling. Or Lewis's free mustang tutorial: http://lwg3d.org/forums/showthread.php?t=14554

Lewis
06-02-2007, 09:55 AM
Hi !

"Safe" place for tris on subDs Car would be on FLAT part, try to avoid on any curved areas if possible but sometime it can work quite well and sometime it's almost needed for ending up sharp car line on fender or so. Just be sure it's not too BIG triangle since it'll give you more pinching and it'll break smooth reflection at render later. Show us your exact problem and maybe we can give you idea how to remodel or reshape problem area.

cheers

Matt
06-02-2007, 11:24 AM
I'd say Lewis is on the money there, the dude is a car master! :D

dx394b
06-06-2007, 06:40 PM
Thankyou again for all of the advice. Here is a quick fender with the type of problem I usually run into. I've cut some tris into the corner to see how they behave. There is still a noticably raised area on the corners both in open gl and render. Can triangles be used properly in such an application, or must I use other solutions (5 sided triangles, stronger polyflow..)

Of the cars that I have tried to model most have very sharp squared corners (such as turn signals) on a much more curved surface than the example mesh.

I have tried bandsawing and various ways of knifing though polys, but all of them ruin the smoothness of my mesh.

I appreciate everyone's patience in listening to this drivvel. It is not easy to hear a derranged man repeat himself constantly.

Again, thanks for helping a newcomer.

Lewis
06-06-2007, 07:47 PM
Hi again !

I don't know which car fender (to me this looks like rear bumper) this should be but let's say that sometime you need to use MORE dense mesh to achieve proper insets and that should be planed ahead when you start doing it since later is harder to add cuts. I'm attaching you my version (check 2nd layer) where i just "added" slices and polygons to areas where I think they are needed. If i knew which car is it maybe i'd make totally different polygon flow but this should do the trick for now :)

cheers

dx394b
06-06-2007, 09:48 PM
Woah! Hehe cool. Thanks so much for your help Lewis. I am honoured to have the advice of someone whose work I respect so greatly.

I really appreciate all of the kind advice this community has given me just in these short few days. As a group your all definately high class. Lightwave is a great app, but without all of you it would be nothing.

Thanks again.

D.

dx394b
06-06-2007, 09:50 PM
Also. . I'm sure many of you have seen this, but a tutorial that has helped me out as well..

http://forums.cgsociety.org/showthread.php?f=43&t=156460&page=1&pp=15

Lewis
06-07-2007, 05:58 AM
No problem dx394b - after all we are here to help :).