PDA

View Full Version : Simple 5-polys-meet-at-point Question


Brett H.
11-08-2002, 12:04 AM
Okay, I know there must be a simple solution to this, but it's really screwing up a tut I'm working on, and I can't find a simple solution (and yes, I've definitely RTFM)...

Here goes:
I have to make the transition from foot to ankle, and in order to do so I always end up with 5 polys meeting at one point (see attached pic). When I Subpatch, I get a kink at that point. And no, it's not just an OpenGL artifact, because I've rendered it, and it's still there.

Is there a simple way to make this transition and avoid this problem? It's really got me stumped at the moment. I've tried to triple the polys weld/unweld, etc.

Look at the example to see this in the utmost simplest form.

Any replies appreciated.

Brett

takkun
11-08-2002, 01:04 AM
what tutorial are you working on? Can you post a link?

jinx
11-08-2002, 01:18 AM
have you tried spinning quads?

while in subD mode, select the two bottom polys (horizontally) & hit spin quads(control k), then do other side, rince and repeat....

Jinx

yon dabuda
11-08-2002, 01:51 AM
visualboo:

you're a lightwave newbie at most.

first you have to be good. then you have to know how to use the software.

but, without either one, every program will be the same.

to me those creases are not a limitation, rather i know how to use them to an advantage, and how to avoid them when i want.

Brett H.
11-08-2002, 02:23 AM
Thanks for the replies, guys.
Yeah, it's not really a limitation of LW as much as a limitation of my organic modeling skills.

I figured this one out for myself awhile ago (with pencil and paper, oddly enough ;) ), and I'm just getting back here to post a reply now.

See attached. Yeah, it works fine, like I said, just me staring at the same polys (the model is alot more complicated than the example) for too long, not seeing the obvious.

Thanks again,
Brett

Steve Warner
11-08-2002, 03:34 AM
One thing to keep in mind as you're working with SubD surfaces is that you should always build your rough model (in quads) to resemble your final object as much as possible. SubDs will smooth across surfaces, but they're not really intended to handle extreme angles such as the one in your first post. At 90 degrees, you're pushing what SubDs are designed to do, and that's why you ended up with a kink.

A real leg doesn't meet the foot at a right angle. There's a slight tapering that happens around the ankle. That taper is what yon dabuda added in his image. While you eliminated the kink by adding geometry, you will eventually run into trouble building a realistic foot as your object still has 90 degree angles in it.

Although it's still incomplete, you might want to take a look at the Modeling Overview tutorial on my site. It has some good information that you might find helpful.

http://www.trinitymediainc.com/Tutorials/html/modeling_overview.html

Hang in there and keep at it! :thumbsup:

Steve

Soeren Nielsen
11-08-2002, 04:33 AM
plz not another app war.. childish mmkay

CG.p
11-08-2002, 04:54 AM
Originally posted by yon dabuda
visualboo:

you're a lightwave newbie at most.



Come on... in online forums they are called trolls.


To clarify

troll1 Pronunciation Key (trl)
v. trolled, troll·ing, trolls

# Slang. To patrol (an area) in search for someone or something:




Seems like what you are doing. If is that important to know, why not bring it up in that thread?

yon dabuda
11-08-2002, 05:11 AM
visualboo:

straight copy from your resume, from your website.

computer skills 3d
Max : I know max the best. It's a love hate relationship - Pro
Maya/XSI : I love both of these... soo powerfull - intermediate
Lightwave : Some things I like... a lot I don't - novice/intermediate
Houdini : currently Learning this app - novice

call yourself a novice/intermediate? but you're not a lightwave anything?
i knew not to believe everything, so thats why i said "newbe at Most" :)

"I don't know about you but I love the fact that I can have N-gons and other weird polys in XSI and MAX and not have to worry about gaping HOLES or creases on such a simple model."

that would be lightwave specific newbie mentality. :) what you consider a sub-d problem, i would consider an advantage. what you worry about, i use with ease to my advantage.
so i split my n-gons into tris and quads, i dont see the disadvantage. creases and holes? creases are a good thing if you know how to use it. holes, thats a problem for nurbs, doesnt happen with lightwave.

hey anyways, i've only said good things about xsi. it might have the best sub-d. who knows, even if lightwave's sub-ds are second to xsi, they're still damn good.

and for the price of xsi, if you dont get 10 times the ability of lightwave, id say you're not using the software as much as the software is using you :)

visualboo
11-08-2002, 05:58 AM
Forget it....

Kaiser_Sose
11-08-2002, 06:41 AM
Originally posted by visualboo
Forget it....

hehe

yon dabuda
11-08-2002, 07:41 AM
awww... now it looks like we were talking to ourselves. hehe oh well. :hmm:

CG.p
11-08-2002, 05:09 PM
You guys aren't very nice.

Bwahahahaha

Brett H.
11-09-2002, 08:17 PM
Steve,
I wouldn't normally do a straight 90 for a foot-to-ankle transition, but I was trying to follow a tut, and this is the way they did it. Actually, I didn't solve it by adding geometry, I solved it by eliminating the point at which 5 polys met. I always have problems when these occur. In the image I posted you see added geometry, but I only made those knife cuts to show the end result I desired, not to solve the kink.

Why the heck I couldn't see the solution to this when I was modelling it, I don't know. The tut did it that way, so that's how I built it.

Thanks again for the replies.

Brett

yon dabuda
11-10-2002, 08:13 AM
heh, if you look at the pic i posted ealier more carefully, thats what i showed. :)

LNT
11-10-2002, 03:07 PM
I kind of wonder what possible advantage you see in lw's inability to properly smooth 5 quads sharing the same corner point...

not in the example above but in general

yon dabuda
11-10-2002, 03:58 PM
LNT: i think there is a misunderstanding. lw doesnt have a problem smoothing a 5 poly connection.
it's just the nature of how the surface subdivided that some people have a problem with.
if i had my models on this computer i could show you examples of where i make 3 and 5 poly connetions to get the desired detail and curves while keeping the geomety extremely simple, whereas in other programs, it wouldnt subdivide at the same degree.

yon dabuda
11-10-2002, 05:41 PM
ok here we go.
http://www.tittiwinkle.com/hand.jpg
http://www.tittiwinkle.com/sc.gif

in the hand example, i used a 5 poly curves to define the shape of the nails, i use it to define lines on the hands.

on the face, i use it to define the lines around the eyes,
on the shoulders i use it to define the lines when the shoulder rotates up and down.

you can see i use multiple poly connections in many places without problems and with purpose.

Brett H.
11-10-2002, 07:51 PM
yon dabuda,
yeah, I knew what you were showing me, and that's the same solution I had come up with myself before checking the posts. I was just pointing out to Steve that the extra knife cuts I added in my second post weren't necessary to get the kink smoothed out

The 5-polys-meet point is not really a problem unless I find myself making a sharp angle transition like the one shown. And again, it was simply my own tired eyes looking at the same polys for too long that couldn't see the solution, not what I would consider a limitation in LW sub-d's.

Beautiful hand on that model btw, I really love the detail.

Brett

yon dabuda
11-10-2002, 08:52 PM
thanks brett

i thought it was weird that we both posted the same model, it was nothing. keep up the progress :thumbsup:
ciao.

LNT
11-11-2002, 01:39 AM
really nice models yon,
but I'd rather not use the 5 poly smoothing imperfections as a way of creating skin creases...what if you export the SubD cage to another program and then loose the effect?

not to mention the fact that when you model cars and other semi-organic stuff sharp subdivision edges are nothing but a smoothing algorithm artifact

again,the way you knit the mesh is good but looking at the hand model I can give you a quick example of a couple of spots I would not consider making creases at - whether or not layout fixes this is another matter - in some cases it does in some cases it dont

http://www.aoikenso.net/ap/hand.jpg

yon dabuda
11-11-2002, 04:27 AM
LNT:
you make a good point about exporting. but i tend to use lightwave's renderer with the models i build in lw, and if i do want to export then i would run a metaform or freeze. i dont really think many people have a problem with this though.

the polys you've pointed out have been noted, its just modeller's inability to show the smooth transition between those polygons.
i dont mind since they dont show up in renders, and i could simply spin a few polygons if it bothers me.

if you notice the way the surface is subdivided, being able to see a crease or not depends a lot on the subdivision level. at an extremely high level where you cant see the divisions, you would see the surface render as it looks in modeller with all its display inabilities.
but then that would be like setting sub-d to 50, that would be stupid.

anyhowz, im kinda getting tired of explaining. hope you dont mind if i dont continue.

hey, no one has to agree with me, i dont have a problem with people having different opionions.
this is what discussion groups are about, discussion. if i cant make my points, then i guess its my fault :) *sometimes.
peace

LNT
11-11-2002, 06:00 AM
it's a minor issue anyways and you're right it can be curred by slightly altering the topology of the model
but it does take time nonetheless when you model things that have to be shiny/reflective and very smooth at the same time

Brett H.
11-11-2002, 11:56 PM
Sorry to have caused any misunderstanding...maybe if this wasn't my first real attempt at building anything organic I wouldn't run into these problems. I find that the few kinks I do have which are caused by 5-poly-at-a-point (which I'm finding really hard to avoid when making transitions from one direction to the other, at roughly 90 degrees--e.g. crotch area to upper thigh, etc.) do not appear at render time, even with a low sub-d level. So, my original statement that it wasn't just an OpenGL artifact is not true in all cases. It was true in the example, but I've come across a few kinks since, and they disappear in the render, coming out perfectly smooth from all angles.

Thanks again guys,
Brett

Brett H.
11-12-2002, 12:18 AM
Okay, so one more thing...

How does one handle such things, if I were to want to make a "perfect" quad model that avoids 5-poly-points? Here's a simple example that I don't see such a simple solution for. It's not a matter of just doing what I (and yon dabuda) did with the previous example. As you can see, there couldn't be a "plan your model with quads" type thing, because quads are all I have.

Just a simple problem really, but I don't really know how to overcome it. I know it will be rendered in LW and won't really matter that a kink will form where I've circled the 5-poly-point, but what if I want to export it? Are you tired of this subject yet? ;)

The example is very simple to get the point across.

Brett

yon dabuda
11-12-2002, 02:47 AM
if you want to run a quick chek on how it wil look exactly, just do a freeze and make sure smooth is checked under surface setting.
if you dont set your subdivision too high(over10) it should look fine.

yon dabuda
11-12-2002, 03:00 AM
but the bad thing about my argument is that i've requested for selectable sub-division types for the renderer before, such as the metaform version. would definately be nice to have options :)
would kick lw's sub-ds up a notch.

CGTalk Moderation
01-13-2006, 10:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.