Loft Defects

[highenduser]

I want to talk about 2 defects of the loft tool.

-1 If you loft many curves and 2 of them are very close, it gives a bad result.

-2 If you loft 2 curves wich one have a lot of vertex on the right side of the curve for istance, and one have
an uniform distribuition of the vertex, it give a probably unwanted result.

What do you think ?

[joojaa]

[li]Could you post image, but basically it uses a trough point interpolation, so in way its like drawing a EP curve not a CV curve (draw a EP curve like this and you'll see), now because the interpolation must hit this point it may need to loop. Around and because your precicion on very close by point is probably not sanely on the paths current delta it will look wonky. This is very much the way it has to work. (if you must turn in a tight corner you have no choise but to offshoot if the tangent is towards the next point).

personally i like drawing cv curves much more than ep curves because of this (as a drag a chord it has more possibility to do good shape), and it gives me overall more control, tough it dont form that cross section! So what i do isntead is:
CODE
//select more than 4 Curves
loft -ch 1 -u 0 -c 0 -ar 1 -d 1
     -ss 1 -rn 0 -po 0 -rsn true;
rebuildSurface -ch 1 -rpo 1 -rt 0 -end 1 -kr 0 -kcp 1
               -kc 0 -su 0 -du 3 -sv 0 -dv 3 -tol 0.01
               -fr 0  -dir 2;

[/li][li]EP's get matched to EP's if you don't have same numbers then the result is unpredictable since the computer needs to guess yes (it is in general stupid to let computers do stuff unsupervised like this) otherwise its like expected.

Also pay attention to the direction of curves and see that their start ends match.[/li]

[highenduser]

Ho yeah, the pics !

1.
http://imageshack.us

2.

Good result:
http://imageshack.us
Unwanted result:
http://imageshack.us
The deformation of the "mountain" is not straight.
Both curves have the same number of CVs.

[highenduser]

Ok , thanks for the answare !

1.
I tryed drawing cv and ep curves.
It cant be linear and uniform=off gives me a bad result again
(it fix that problem bud give a strange shape).
I tryed your code, and it works well, but the surface dont match the profiles very well.
What do u mean "you have no choise but to offshoot..." ?

2.
All the curves have the same number of cvs !
Directions are ok.

Thankyou very much.

[joojaa]

Damn the picture cuts off too much, but it looks like your selection order is just wrong (obviously selection order matters, as fort selected connects to second second to third and thir to fourth). Anyway yes my method means you need to think the tool very differently. you need to think in terms control points versus surface is here.

[li][img]style_emoticons/<#EMO_DIR#>/laugh.gif[/img] That is NOT a defect, it is the way the tool has to work otherwise you could never ever succeed in making anything other than straight shapes. See what you are defining is not only the cross sections of the loft but also the point flows. Theres plenty of reason to want locally slatted lines (actually more so than straight).

the tool matches points to points! A tool does not do a defect just because you want it to be different tool than you think it should. Use birail plus! It allows you to define match this to this, lines. But very obviously you will get much more points for the final surface then you bargained with. (it is NOT possible to make a patch that is straight but has more point one side than another, but if you can explain how that should work out then id be happy to build a tool that does.)[/li]

[highenduser]

1. No , the selection order is ok.
2. ...

Idk Maya should think of the shape of the curve, not of the cv or cp !
No! The brail tool gives me these plus other troubles !!!

[joojaa]

QUOTE(highenduser @ 09/05/07, 03:17 AM) [snapback]272811[/snapback]
dk Maya should think of the shape of the curve, not of the cv or cp !

It does it just thinks interpolation differently than you do, flow of the shape is more important that each cross section for the 3 dimensional picture, so if you let go of the flow of shape then you end up loosing more then 50% of the end result, but more importantly 50% of user controll (trust me you dont want that)!. Theres nothing that states you cant make such a tool but you wont be calling it a loft, because the definition of a 3d loft is match point to point (it work that way in max, proe, catia, rhino you name it). Besides, how on earth could you control the amount of points and their indivisual directions else?

See the picture forms from 2 dimension, if you just stump the second dimension to the computers arms, you get a random result. How ever you can rebuild the surfaces to match points by % of distance absolute distance, or a parameter space (thats what you have now)

You cant blame a tool if it does what its supposed to do (quite exactly, and quite exactly how it was designed to work, 90% of the time people rely on THE behavior you don't want) and you just want it to operate differently I mean how would yu loft a eye shape if it wouldn't follow the local flow? How would you control the amount of points! You a hammer ist bad tool just because your trying to attach screws with it.

(it is possible to make this tool in mel)

Anyway could you post the second picture as a zipped up ma file and i can have looksee. It should work and does for me no problems. (is you options set to closed by the way?)

QUOTE
No! The brail tool gives me these plus other troubles !!!

Tools aren't broken just because you don't understand them, or cant get them to work.

I made a demo video of using birail+ for this (it can be quite easily automated in mel, i could make it better by connecting points form origin back too, efficiently creating a patch tool, but i don't have the time):

birail+ (1.6 Mb 264 qt mov sorry for the bloopers i watched television while i did this)

Now if you complain about the amount of resulting points then that is probably impossible (if it isnt id be glad to hear the solution, without degrading accuracy) without creating a new patch type that dont have the limitations of sub divs, Nurbs, beziers, T splines. And would quite frankly be just hard to use, as opposed to the current tools and give very little control in return.

With polygons you can offcourse delete the extra ones.

[highenduser]

Ok i think im understanding what you mean. thankyou very much fo the answers .
I made a scene .ma file with 1 and 2 examples + 1 extra bonus birail3 one!
Just tell me how to send u a zip ? (since in this forum i cant attach files)

[joojaa]

Put it up on some site and link the uri

[highenduser]

http://rapidshare.com/files/54099733/loft.zip