Edge Loops & You

[Fox Raptor]

Yo guys, long time no post. I'll save the catch-ups for another thread, but I have a question that's been bugging me lately and I figured it seemed a little newb-ish, so I thought this would be the place to put it.

 

The topic description pretty much says it all; I've been reading alot of 3D tutorials about edgeloops and I'd like to know exactly how they make facial expressions easier to work with. Maybe I'm just missing something cause I haven't really done much outside of blinking and some fairly simplistic expression work, but I feel like I'm kinda missing something here.

 

Thanks in advance and I hope you hear from you guys soon.

[Dhar]

That is more relevant to polygon based software.

 

I found this link that may give an overall idea http://cube.phlatt.net/home/spiraloid/tutorial/modeling.html

[Fox Raptor]

So this is one of those things I really don't have to consider while using AM?

[Dhar]

So this is one of those things I really don't have to consider while using AM?

 

Correct. A:M is totally spline and patch based. No polygons, no sub-divisions. Which makes life much easier

[NancyGormezano]

So this is one of those things I really don't have to consider while using AM?

It's good to consider the spline layout for the face especially for characters that will animate well - When I browsed to the article that Dhar suggested - there was an image that might be used as a sorta starting "template" for the layout of face splines in A:M

 

There are many different ways to layout splines - depending on the model's character - I am a rubbish modeler - but there are others on this forum who can definitely help guide you if you start your character and post a wip

[robcat2075]

based on that article, would I be wrong to say that splines already do what edge-loops do? It looks like the strategy for placing edge loops is the similar to placing splines?

[entity]

I read a lot about Edge loops:

They control the topology of the surface, and they follow the pattern of muscles and bone structure under the skin. It also helps you see your character's volumes better.

Doing this with splines gives you less to try to smartskin to correct the shape of moving geometry.

 

Something interesting about controlling splines to make a hard edge: The closer two loops are, the harder the ridge or edge you can create.

 

Thanks for bringing this up, it's been a while since I modeled something.

[robcat2075]

I don't get how they help you see the volume of your model. Either you've put modeled a shape or you haven't.

 

These edge loops reside on the surface of the model, right? Where the polygons already are, right?

[zandoriastudios]

You need to give yourself enough geometry to shape your face in all of it's poses. The mistake that I see often is being so obsessed with low patch count, that you don't have enough geometry to create the shapes beyond just a neutral position.

 

whether you call it an edge loop or a spline ring, it serves the same purpose. Look at an arm--notice how you will typically have an extra ring around each side of a joint? that is so you have enough geometry to shape the joint when it bends. When you look at the eye or mouth, usually you have a couple of rings of splines extruded out from the opening. These give you the CPs that you need to shape the eyes and especially the mouth at the extreme shapes.

 

Take a look at any of Jim Talbot's models (on the extra's CD) and you will see mastery of this principle.

[ypoissant]

"Edge loops" is a concept created to teach good modeling habits for polygon modelers. They don't have the luxury of natural spline continuity so they had to invent a way to talk about this important modeling technique. This said, the modeling technque itself is still very relevant to spline modeling except that in our case, we cannot use the term "edge loop" because we don't have edges.

 

The basic idea of the modeling technique, is that you should try to lay out your splines in such a way that it will follow the natural contours of the form your are modeling and intend to animate. Nancy is correct, the above template could very be well used to layout splines. In fact, that is more or less the spline layout that experienced modelers do. So there you see the obvious loops around the eyes and loops around the mouth. But what is less obvious, is the loop that follow the naso-labial furrow and other flowing forms of the face.

[phatso]

So, YP, if I understand you the concept of "edge loop" in a polygon program is just a mental construct - you mentally group the segments that abut a hole, and call them a loop. A fudge, in other words, like polygon modelling itself.

[entity]

I don't get how they help you see the volume of your model. Either you've put modeled a shape or you haven't.

 

These edge loops reside on the surface of the model, right? Where the polygons already are, right?

As opposed to a haphazard grid of splines, just placed there to connect the parts of the face or body together. The loops/ continuos splines follow the contours of the surface shapes/volumes.

[ypoissant]

So, YP, if I understand you the concept of "edge loop" in a polygon program is just a mental construct - you mentally group the segments that abut a hole, and call them a loop. A fudge, in other words, like polygon modelling itself.

Yes. A mental construct. I would not call that a fudge though. It is more like vanishing points and lines when you draw in perspective. They are usefull concepts. But polygon models don't really have an edge loop structure that would hold the chain of edges that constitute an edge loop. The edge loop is really in the eye of the modeler. This is unlike a spline which have an intrinsic continuity that can span several patches.