[AST] Porsche 962/956

[[킹]]

First of, this project is mainly aimed for myself to learn AST. I've had some time using Rhino and AST seems very very different. Anyway, here's some screenshots of the current progress. Yes, it's not much but I need some critiques from you guys.

[Erik_S]

well looks like a good start, good luck with learning it man It can be a bitch for what i've heard hehe

[[킹]]

Ok, it's doing exactly what you've said right now lol.

I'm trying to cut the front part of the car (the small yellow triangle) and it did not worked. Here's what I did;

-project a straight line curve with 1 degree on to the yellow surface (successful)
-trim the small triangular surface but nothing seemed to change. the triangle remains there :banghead: promptline did not give any error.

Any idea how do I trim it away?

[[킹]]

Never mind the previous post, I sorted it out. It was with the construction tolerance values which seemed to be too large.

Anyway, here's another one :P
The blend surface doesn't seemed to have worked out well for me. The zebra shows crooked lines between the blend surface and the main surface. What I did was construct a blend curve from the edge of 'Surface 1' to the edge of another surface with G4 and 5 degree setting and used the rail function. Help please?

[74j4]

Align it.

[ravenzep]

Are you starting learning Alias? Well, for someone learning Alias, modelling with G4 is pretty mind blowing. G3 would be too.
Dont focus on achieving such Continuity. If you can achieve G2 continuity it s pretty good already. And not easy.

Anyway, you are trying to achieve G4 continuity, on both sides (blend), with a degree 5 curve? That s totally impossible.
You dont have enough cv s for that. A degree 5 curve allows you to achieve only G2 at both ends. Try counting the CVs. I hope you understand.

If i can give you some hints, i would advise you to work with degree 5 curves, degree 5 surfaces, and G2 continuities.
Alias is a surface modeller, as opposed to a solid modeller, meaning, it doesnt like too much trimmed surfaces. You should try to avoid that.

The way you started the car, although it seems to be logical and ok, i dont think is the adequate . How are you going to continue the car from here onwards? I think it will give you some problems. hmmm, i cant really know. The best way to model in alias, is to build your model from small patches where needed, and big slabs. Try to draw a patch layout on paper, before u actually start to model in 3d. That helps a lot. Another thing i would advise you not to worry too much, is to use 1 span patches or surfaces.
It will be quite dificult to do, and if you use 2 or 3 spans in some parts, it will be perfectly fine for a good render.
Dont use too tight tolerances. Besides not being needed for some cool renderings, they will make it very hard to achieving G2 continuities especially with 1 span. Even in simple surfaces. e.g. catia V5 tolerances are too high and not needed for people who model having in mind visualisation purposes. You aint going to machine the car, are you?

I hope i shed some light into your learning and practice. And congratulations for using Alias, which is a remarkable piece of software. Good luck with your work and dont give up. It s not supposed to be easy and needs tons of practice

REGARDS:buttrock:

[[킹]]

@74j4;
Thanks! I finally solved the issue.

@ravenzep;
Ok, I'll do the surfaces in G2 continuity then

With 5deg curve and surface do you mean that the surface created would be a single span? Is there anyway I can know if the surface is single span in AST? (what's the difference between single span and multi span? is there any disadvantage?)

And also, what do you mean by avoiding trimmed surfaces in AST? Take the pink surface in the attachment below for example. Do you mean that the pink surface should be created by using rail with 1 or 2 gen curve and 2 rail curve instead of making one large square surface and cut it into the shape as desired?

Please excuse my noobity or whatever you may call it :P

edit : sh*t accidentally hit the enter button before finishing.

[ShazzleCov]

If you want to know if a surface has spans in it, they are shown using lines on the surface, the picture you attached above has one span, so im guessing it was trimmed because spans should not hit joining sides, they should hit the opposite side, you could quite easily remake that surface into a single span square.

Also the best way to avoid spans, in most tools, if you go to advanced most of them will have an explicit control which allows you to dictate how many degrees the surface is and how many spans, so ideally 5 by 5, have a look mess about and see what you can do, a lot of it is experimentation.

[ravenzep]

I thought you would know such basics, as you are using alias. It s a total different animal (better) than rhino.
Ok man, no problem. Send me an email, and i ll make the basic theory of nurbs (nomenclature, etc) clear to you in 5 minutes. I ll be glad to help.


And YES, that pink surface could and should be perfectly a untrimmed surface created by a square.You could do that surface by trimming, but after you would trim convert, which would give you an untrimmed surface from that very shape. Personally, i dont like the birail tool to make the shapes that could be built by square. I only use it in very particular cases, where the cross sections change along the path .
I wanted to call you by your name, but your identification seems to be a weird glyph. LOL.

Regards

[Helicase]

Your doing the right thing though just jumping into the program. But, i got this awesome old tut from Sektor 41 that helped me learn it. To bad that sites been down for a LONG time.

[tugra]

Did no one back up those much revered tut from Sektor 41??