SomeArtist - The Pole

[patrick]

'SomeArtist' had a great following inspiring a great set of discussions on a few forums regarding some modeling methods. 'The Pole', was a hugely popular discussion regarding the flow of polygons and even debated some popular polygon loop methods
<post 1>



Have a careful look at this Triangle image because it holds the key to mastering Sub-D modeling. Triangle is the smallest element in a 3d model and by knowing how to solve Triangles you will make a big leap forward as a 3d modeler. In fact, once you're through with this thread you'll be modeling like Bay Raitt! (No kidding!)

But first we must understand poles and before you read on make sure to forget what you have learned about Poles! Here is another way of looking at it.

The (E) and (N)

Poles in general are not good for your Organic models however, you cannot avoid the 5 and 3 edges poles and instead of being afraid of them why not try to understand them? Many beginners cannot advance to the next level because of this blockage (poles) and so they tend to fear them and then Topology becomes difficult and they fear that too. The 5 and 3 edges poles are very special poles, 6 and beyond are not special so you can ignore them completely and since there are only two special poles we're going to give them names.

The E(5) Pole



The E pole is actually an “Extrude Pole” (E for short). When you extrude a Quad you will get 4 Es!



When you extrude for the mouth, eye and ear you'll get 4 Es each. When you extrude for the arm/leg you also get Es.



The N(3) Pole



When you model a nose you'll get this 3 edges pole and there is no way you can remove it because if you do then that nose will not look like a nose and so it was meant to be there (Keep that in mind).




I call this 3 edges pole “The Nose-Pole” (N for short). The Nose is a very special case in that you get “E” and “N” next to each other, I call this the “EN” case. This “EN” situation will surfaces once you get into detailing like the nose here. If you remove this “EN” you will remove the detail for the nose and in the image above I have separated E and N with a Loopcut (more on this later).


Now why is the talk on Poles important? Poles control how things flow in your topology, have a look at the image below and I'll get back later.

[patrick]

The talk on poles will helps us to understand flows and smooth/bumpiness of our meshs. So far Flow was brought up so I'm going to continue with flows then later I'll talk about smoothness and bumpiness.

Flows

The Es cannot be eliminated but the Ns can be. Since we can't really eliminate poles in general what we can do is hide them and eventually they will be gone and that is the trick.



A good example of this is the NPoles for the forehead and the back (if you started with a Box that is). For the forehead you hide it inside the eye and for the back you hide it inside the Ear. You do it via a method called “UnPole” which I will go in-depth later. Now, just because you can remove NPoles doesn't mean you should do it! Some Npoles are meant to be there like the Nose and when you get into detailing the muscles for the human body you will get a lot of NPoles/EPoles since Poles control flows. A model with complicated flows will have a lot of Poles and vice-versa.

I have argued with a much more experienced modeler about the Npole for the forehead. He told me having the Npole there gives better control for the forehead. Now think about that for a moment.. we all know that Poles make our meshs bumpy. Better control with a price and that price is “Bumpiness” and we all know that the forehead is not 100% smooth! (Underneath is a skull) So yes, you can leave the Npole there for better control of the forehead. Whether you should leave that Npole there or not is up to you. To say “Should I remove it” is the same as saying “Can I use Ngon?” And the answer is always “If that is what you want, then that is what you must do. There are no rules.” The picture will get clearer once I talk about smooth/bump later.

E



When you extrude a poly you instantly created a circular flow (dark orange in image). In some cases it's good to have a circular flow with Es on the same lane (yellow), however in the case of a human head it's very bad!



(A): According to the screenshots of human head from professional artists in my collection, this Loop for the mouth is important. You cannot achieve this loop with both Es on the same lane so the trick is to move the upper E to the left lane (B). The next time you see both Es on the same lane you can be sure that it will form a Circular Loop.. If you remove (shifting it elsewhere) the upper E you will break the circular Loop like you are seeing it here.



Instead of shifting the upper E I shifted the bottom and this is the result. Pay attention to poles because they are your guide to better flows!


Quote:
when you extrude a quad you get EN not just E
Nice observation!

There are much more to Poles than I first thought. For example, when you extrude a POLY that has N pole as one of its corners, you will convert that N into nothiing (no pole)

[patrick]

Earlier I said that when you see two Es on the same lane you can be sure that it will form a Circular Loop. Here are two more images (below) to confirm that observation.



Pay attention to the Es because by shifting one back and forth you can achieve “predictable” flows! There are no guesswork here.



You can use this dot/curve image as guide.

Key-Loop/Fill-Loop


Earlier in the “Form” thread I mentioned the Key and Fill concept and how you can use it in anything that you do. Key-XXX/Fill-XXX, where XXX can be anything and in this case they are Key-Loop/Fill-Loop. When you look at Edgeloop references out there what you are seeing is a bunch of Key-Loops for you to Fill in.



In a KeyLoop stage Poles are close to each other and when you add in the Fill(s) they start to fall apart after the tweak (It's difficult to keep them together after the Fill(s)). During the fill stage you can increase the resolution for the KeyLoop that you're working on and while doing so you can move a specific pole away to a place where you think it belongs. If you have been collecting wireframe references now is a good time to open them and observe. Immediately you'll learn that all modelers are different in the way they place Poles.



There is no right or wrong but the general rule is: Don't put them in areas that deform and in the image above (cyan dot) I put it there because I want it there. When I get into deformation and that area doesn't deform well then I will do something about it but for now I will leave it there. I leave it there because I have looked through many wireframes and I see that pole there... somewhere there and it doesn't have to be exactly where.

If you're still afraid of POLES then have a look at this thread by Glen: BREAK THE SYMMETRY

In that thread Glen explains to us that the human faces are not 100% perfect. Why are we forgetting this fact? The human faces have dimple, crack, holes and it's never perfect. Now just imagine that poles can be used to represent these features. Hey, if someone say why you have a lot of Poles in your model, just make up a story and say that this character had a car accident!

[patrick]

<Post by Toontje>
If I learned something is to take a step back and analyse too what the basics are of edge loops and what the functions are of the poles in addition to what you already explained. So permit me to present my findings (and please don't hold back any critiques)

I found that there are 4 ways in which poles are produced on the mesh:
1) extrusion
2) spin quad/ spin edge
3) rip (help me out here, by lack of a better term. It is wath the V key does in Blender.. but I explain more in detail later)
4) Knife tool

I also found out also that edgeloops may overlap on different ways without interfering with eachother

EXTRUSION:

After you invoke the extrude command, you may pull a 'limb' out the mesh, or confirming the command right away, leaving an edgeloop on the mesh.



Something was said in the affect that a pole can not be elliminated? Well..you could do it like this:



After the cuts, you are left with 3 pairs of triangles that can be merged into 3 quads. The result looks a little funky, but if you elliminate another ADJECENT E pole, you are left with a C-loop




Edgeloops can coexist. So in this way you don't have to be afraid that there might be some dire consecuenses that edgeloops you create might disrupt edgeloops that are already present:



As you can see, loops can touch eachother, intersect or be a part of each outer loop, which is cool. So this means that you can form your eyes loop, mouth loop and pull a nose loop that intersect the mouth (or mouth-nosetip loop) without a hassle. The nose loop could be converted in a C-loop with the technique I mentioned above.

[patrick]

C-Loop Topology



This incomplete head was modeled entirely in Blender from a BOX and it used the CLoop topology. If you're a beginner I highly recommend that you start with this Loop because it's easy and can save you a lot of stress since you're learning best of all you can create amazing result! As you can see from the image above, I have gone far and still using that Loop. Now that I understand Topology after using the Cloop I can branch to other Loops or even invent my own. Here is the Key:



When I look at a wireframe I look for Poles because I can copy the topology using Poles as guide since Pole(s) define a Topology, just look for the Poles. Last, do not be too obsessed with Topologies just read the SUB-D Primer and you'll learn that having a clean/kick-arse Topology doesn't mean it will deform correctly during animation. However for still images/Zbrush sculpting a CLEAN MESH is best. When you get into deformation and things doesn't work out just use the knowledge here to change/adapt which is better than trying to learn all the topologies that exist out there.

Poleless



This model is now 100% Poleless thanks to shahar2k at Wings3Ds forum who have shown me the trick and here's the direct quote (for Wings3D):

Quote:
shahar2k:

a little experiment to try,
1 - take a model made out of 100% quads (any model that is smoothed once already for example)
2 - set all the edges to "hard"
3 - smooth the entire model once,
4 - select all "hard" edges and delete them,
5 - select all "isolated vertices" and delete those too

The Key idea is to subdivide your mesh and keep the subdivided version while deleting everything else. All the EPoles will be converted into Ngons and all the NPoles will be converted into Triangles! To move Ngons around is to move Epoles around and to move Triangles around is to move Npoles around which is one way or you can do it directly after you subdivided. Once you have a poleless model you can start your Poleless quest, Bay Raitt anyone?

Poleless conversion
Epole --> Ngon
Npole --> Triangle

I don't know why anyone would want to do this and I guess the only way for me to find out is to get into deformation later. The good thing about a Poleless model is that you can select an Edge's EdgeLoop and it will run all the way from start to finish, nothing will be in its way (No poles).

Note: Don't try this in Blender

A Demonstration

Here is a very short and powerful demonstration before I get to the actual Technique (next post).



Take a look at (A) and what you'll see is the Loop I created on purpose. I want that Loop there but I also want another one, look at (B)-Yellow Highlight. From what we know, 2 Es on the same lane will create a circular flow and so I put a pole as pointed by the White Arrow.



Now I have it! BUT there is a problem. Look closely and you'll see that the original flow got broken (green) so the question is: How do I create a secondary(B) flow while keeping the Primary(A)? The trick is to think one step ahead.

One flow cannot go in both directions! You cannot have one flow that go LEFT AND RIGHT. To do that you must split the main flow into two.



So that one is reserved for the main flow while the second one is for, whatever you want.



Instead of splitting it into two I made 2 fills which gave me 3 flow.



As you can see, there are no guesswork here.

Quote:
Any chance of a look back there?



modeling the nose is easy with Poly-by-Poly and for a box I still haven't figured out a logical way yet. If you're looking for the best topo for the nose this image is not it. There are better flows for the nose out there and I'll get to Toontje's post later.

[patrick]

<Post by Toontje>

I was also looking at the workings of edge loops and pole at more atomic level and I like to explain what I found about using the "spin edge" or "spin quad" command.

I don't know if Spin Edge is available for all packages. I know for a fact that you can perform a spin edge in Blender and Lightwave.

If you have a grid and you perform a spinedge somewhere, 2 N poles and 2 E poles will be produced. It seems that in normal circumstances the number of E-poles is equal to the number of N-poles.




As you can see, after a spin, you are left with 2 loops like railroad tracks opposing eachother. I maybe wrong here, but I found that you can follow the loops better if you look at the N-poles instead of the E-poles. You see in the picture above that the edge loops get bent at the N-poles.

The cool thing about the spin egde command is that you can bend the loops anyway you like. One major drawback is that each spin edge spawns a new loop.



As you can see that if you intent to use spin edge to create loops, you will get this rather nasty side effect.

But you can use spinquands in situations to eleminate poles (just reverse the procedure above by spinning the edge in the oppisite direction) or to correct edge flow, which I will explain in a later stadium.

Remember the simple extrusion that leads to a closed loop? Well, you can make a closed loop too with edge spin and judge for yourself how much it differs from the extrusion method:



Here you have a closed edgeloop, but with side loops bordering its corners.

On a final note, you can collapse those side loops thus elliminating one N- and E-pole also like this:



I deleted the edgeloop in the lower right corner by collapsing it. In Blender you should be able to delete this loop, but I get an error saying that it is intersecting itself (must be a bug, because it clearly does not intersect itself). So I merged the verts one at a time. Maybe it is possible to elleminate poles in general by collapsing (unwanted) edgeloops? I'll have to experiment a little to find out if this is true for all situations.

I guess the moral of the story is: Beware of spin edge.... for now.

[patrick]

Hello,

Today I'll be talking about mesh ripping. I don't know what the command should be called, or if there is a similar command in another package than Blender. If anyone has a better name for it, I'm interested.

So, what's up? The tools that I'm explaining here are tools that have an effect on the topology because they produce poles. I didn't quiete master the ins and out of this technique, but let me present to you what I found out so far.

What is mesh ripping? With this tool (Vkey for Blender), you rip the mesh open by pulling at a vertex. In Blender you should fill the hole it produces yourself.



The mesh above was ripped open at the upper N-pole. After that you may want to fill the resulting hole. In these scenarios I will fill the hole.
So, like spin edge, rip mesh produces a pair of N-poles and E-poles. Like I said before, the direction of the faceloop (I agree on the terminology too) is determend by the N-pole.

The resulting hole stands out like a diamond in the mesh. If you encounter such situations, and you a meaning to eliminate poles, just merge those N-poles together to get rid of all the neighbourhing poles (thus effectively reversing the mesh rip).

After a spin edge, you are left with pair of poles opposing eachother diagonaly. With mesh rip the poles are opposing verticaly or horizontaly.

So far I have found these uses for mesh rip (topology wise that is):
1) Moving E-poles around (YES )
2) Creating C-loops

Because of the lack of Ngons support in Blender, you have to manualy complement the mesh ripping operation by using the cut tool and merge triangles into quads. But nevertheless, mesh rip is a very powerful tool.

First, Creating C-loops:

The rip mesh tool is very flexible in conjuction with the knife tool. Depending on the method, you are left with a single C-loop, or with a mirror pair of C-loops.

Creating a single loop:



And after the cut:



This was a very minimalistic loop because I ripped at only one vertex.

[patrick]

If you want to make a much wider loop, you must rip all the vertices in a row. You need to use the knife tool to obtain the face loop. Depending of how you cut the mesh, the results will vary.

To obtain a single broader face loop:



Here I'll cut before I fill the hole, else there will be triangles in the corners



And then after filling the holes and cutting (and smoothing) you are left with one C-loop (by the way: I assume that C-loop means C shaped loop and not closed loop).



There is a number of ways to make a number of wacky face loops/ edge loops with this method, but i suggest to keep it simple because simplicity and predictability is the name of the game here.

Lets try to make a a closed loop like in a extrusion:

[patrick]

Thanks Layer for the comments. Regarding "rip", I'll call it "break" from now on.

My posts are based on non NGon workflow only. I don't have any real experience with NGon's, so don't hold that against me. However I think that every package must be able to deal with tris quads only....


Let's continue where we left of:

After the last operation you are left with this:



Wich is identical to an extrude operation of course. So let us keep in our back of our mind that the break command and the extrude command is somehow related.


Now then, there are a lot of ways to finish of the break mesh operation with the knife tool, each producing its own unique outcome.

Here I will demostrate the easiest way to use the knife tool, but it produces a mirror loop. This effect may or may not be desirable depending on the situation.

After a break, fill the holes. You are left with 2 tris in each corner. Cut through this so the tris are doubled, which means you can join them back to form quads (*).



And you are left with two overlapping C-loops:



I've experimented a little with ways to complete the loop after a break, but the other results were a little funky, like one c-loop being overlapped by two opposing c-loops.

You might think that a break is the oppisite of a vertex merge, but it isn't. In an all quad mesh, a vertex merge can't be undone by a break.

But what a break does is removing one edge from a vertex! But a beak will add an extra edge on both its corners. Armed with that knowlegde I will show you tomorow how to move poles around. Essentialy you are adding an edge to the N-pole making a 4 edged vertex (normal quad) and you are removing an edge from the E-pole, and at the same time you are adding an edge to a vertex outside the loop. It sounds like a mouth full, but is just 2 simple actions.

*: For those "I hate tris" folks out there, that's a sure way to eliminate tris, but it could leave you with a jumble of unwanted edge loops. Best is to cut through the shortest route.

[patrick]

For this post I'm going to talk about the technique since people are waiting for it then later I'll respond to the posts before this one.

UnPole

Earlier in my first post I showed you the Triangle image and told you that it held the key to mastering Sub-D modeling.



The top row is what you have been living with and the bottom row is the UnPole technique. Combine this technique with Spin Quad (plus the knowledge on Poles) and you have just mastered SUB-D modeling! Here is another way to solve the Triangle.



Keep in mind that I did not invent any of the above I am only giving it a name and raising awareness (especially the bottom row in the first image). Now that you can solve Triangles you can turn a messy mesh into a good looking mesh! First let's look at the SpinQuad and Unpole.

Note: You need to know the above if you're planning to model in Blender since Blender produces a lot of Triangles.

SpinQuad/UnPole

SpinQuad is a very powerful technique that can change a flow in an instance. All you need to do is select two faces and Spin them.



There are two problems to this technique and they are:

1: The mirror effect.
2: The NPole!

These two problems can be solved by unpoling the Npole and once that Npole is gone the rest will be gone.



I look at Unpole as a technique to clean up the mesh (beside shifting poles).

There are two ways to create/change a flow and they are:

1: From a pole perspective
If you want a pole at a specific location then do not use SpinQuad since it's difficult to visualize the result in your mind. By knowing that two Es on the same lane will create a Circular flow, then it's logical to do it from a pole's perspective.

2: From a SpinQuad perspective
Use SpinQuad when you don't think much about Poles. Sometimes it's logical to use SpinQuad over UnPole and vice-versa!

And last you can combine these two together. I'll get into Shifting poles next for now try and open one of your messy meshs and see if you can look at it from a Triangle perspective.