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Is topology important in SL as in other game engines when creating an avatar?


Porscha Pearl
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Hello guys; 

I am currently creating a female mesh avatar and need some info please.

 

I am wondering if its necessary to retopologize it to be animation friendly or just leave it as it is and not to care about how the topology flows.

 

Also what would be the ideal polycount the avatar should have? An aprox number, so to be smooth and also not as expensive to upload. And actually is there any limit as to how many polys can be uploaded? Cons and prons.

 

 

Thanks in advance.

 

 

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Here are two images of the head so to show you guys...

 

This is the Triangulated one and I can achive really low polycount if it is just Tris (this is not a low poly though)

 

Tris.PNG

 

 

 

and this one is some retopo Ive done turning some into Quads but I want to know if it is really necessary to keep working on it as its time consuming.

quads.png

 

 

There we go! :-)

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Well you can notice some differences in the surface of the retoped model and your first version. I truely think in an use, Second Life or not, it is all preference. Though good topology can make a model cleaner and easier to work with especially if anyone else will ever work with it.

Here is a good read on the subject.

http://cgcookie.com/blender/2012/11/28/why-topology-matters-modeling/

 

If I was to suggest something why not just be topology concious from the start and then you wouldn't need to worry about retoping later. It might not turn out perfect but it would be easier to fix topology errors later then redoing all of it.

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Hello Syle and thanks for the reply :-)

 

This is a sculpt model that I started creating it in Sculptris (it works with triangles only) then I continued working with it in Zbrush as I didnt had the money to purchase the software before, Sculptris was free :-)

Also I had to Decimate the Mesh a couple of times to reduce the polycount as it was close to a million and that proccess makes everything triangles anyways.

I like to not have limits when I creating something, is more fun that way for me but yes unfortunately I have to take the hard path later and retopo it :-P Is by choice.

 

Thanks for the link, I just dont know how important is for SL since the default mesh avatar is triangulated too and for such less polys it works fine when animated, not perfect but I believe if more polys there then it could be much much better with less stretched textures at points that the body bends.

I'm about to retopo it if noone else gives me a good reason to not, just want to make sure before, I hate to have questionmarks in my head! :-P

 

Thank you so much again!

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Porscha Pearl wrote:

I am wondering if its necessary to retopologize it to be animation friendly or just leave it as it is and not to care about how the topology flows.

Nothing is necessary. The better your topology, the less strange deformations you will get when animating and the easier it will be to texture the object/avatar. On a head you won't get any deformations in SL (same for hands), since eyes and mouth aren't animated. The winks and open mouths you can see in SL are morphs on the SL avatar so won't work on any custom mesh.


Also what would be the ideal polycount the avatar should have? An aprox number, so to be smooth and also not as expensive to upload. And actually is there any limit as to how many polys can be uploaded? Cons and prons.

I don't think the expenses on upload should be the leading factor. Lag vs looks should be. The SL avatar has 7000 tris if I'm not mistaken. I would not go over double that for a naked, bald avatar.

There is no direct limit for polygons, but every material on a mesh object can have no more than 64000 vertices. with 8 materials that gives you 512k verts to work with, resulting in approximately 1 million tris. This is a number you might expect for everything on your screen combined, not for a single object.

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"...resulting in approximately 1 million tris"

In fact there is a limit of 174752 triangles, beyond which additional triangles will appear as holes. This is because the 64k vertices per material is (presently - it's reported as a bug) pre-empted by a limit of 21844 triangles per material, after which a new material is "secretly" started by the uploader. It will go on making new materials beyond 8 x 21844 (=174752) triangles, but the extra triangles then get dropped by the limitation to 8 materials, causing the holes. When you go over the 21844 triangle limit, the vertex count will start to climb steeply, even with smooth shading, because the materials get highly interspersed so that the same vertices have to appear in multiple material lists. So the moral of the story is to keep below 21844 triangles per material, for now, if you want to avoid some unexpected effects.

(PS I would put the jira link, but that's no good to anyone any more).

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Pretty much everything has been said, but do keep in mind that the lower amount of poly/tris you use the less lag users rendering the avatar receive. SL already has a ton of lag because of bad practices due to users, (From hardware view not server lag) I've seen some shirts that are a ridiculous number like oh say 60,000. Looks awesome, tons of people wear them...but they lag everyone like crazy. Of course people just blame the server ^.^

60,000 vertices is a good deal more than some video game levels/maps. Thats quite frankly ridiculous when you have four people wearing the shirt made by the same maker 240,000 vertices! If you can reduce, do!

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Most being said already and yet still maybe one or two things to add:

Topology is the general flow of the models structure. Its Edges, Vertices and Faces. 

(to drop some keywords as : edgeflow, edgeloops, and so on).

It has rather less to do with the count of any of these.  

 

Topology is important for several certain reasons:

- correct behavior when animated  (topology should be seen as anatomically)

- simulating and shaping natural and artificial forms correctly

- a clean structure to model from (subdividing, bending, extending, further shaping etc)

 

To add: a good topology also allows us to decimate models in a better controllable way. (not always when using decimator algorithms because they just go by their mathematical base and also mostly break the model back into tris - which we don't want while we are still in the modeling process -  but especially when you start 'optimizing' your model and breaking it down and do what so many call 'handstitching' by merging vertices along certain loops, have several rows of loops connect with a less dense area etc)

 

@ Porscha (and everyone else interested) here is a good example of what an actual Face-Topology should look like.

http://wiki.polycount.com/FaceTopology

And Apart from the Topology part you can clearly see where your model has too many faces (hence the backpart of the head and the sides. Watch the examples on the link to see how they reduce and handstitch things together to spare every needed face and still keeping a completely perfect topology)

By the looks of it your Face was rather sculpted from a Sphere or Dynamesh in ZBr. as I assume. Then actually having a constructed topology.  (my apologies when I am wrong - just trying to help: ))
(and maybe in the first picture being broken down by the Decimator plugin? And on Image 2 overworked with Q-Remesher / or Dynamesh?)

Tools like QMesher can help you to get the all over topology more clean by evening things out but they do not really provide the control a manual retopology on a model would do. Some offer that you can draw some kind of edgeflow on it, but even that has very limited uses and mostly requires 'cleaning up'.

Topology - just as many other parts of modeling and / or 3D in general can almost be an own artform. =)

There are several ways to actually construct a model as in creating its topology:

- Cube-Modeling, (or starting with another geometric arranged assortment of quads)
- Polygon- Extruding
- Or Sculpting with programs like Zbrush and then manually (with internal or external software) retopologizing. 


Whereby you would control where u have certain loops of faces go along in order to reach :

- a good topology

- and as many as needed (depends on the engine its going to be used in) and as less as anyhow possible to achieve a certain outcome.

After all this gobbledygook about topology to also add an answer to your question from my view:

quote: Is topology important in SL as in other game engines when creating an avatar?

- yes and no.
- yes: because it will enable you to avoid wrong shaped areas (like for example the forehead on your model is rather like a beveled cube and doesn't provide you with the necessary flow of  making certain shape indents etc)
- yes: because it will enable you to animate / rigg and skin a mesh in a good working way
- yes: because it allows you to get back and forth along all steps coming your way (UV unwrapping, subdivision, displacement, mirroring and many more)
- no (for the face, hand and feet): since we can not animate a face yet (there are no corresponding bones in the SL avatar skeleton) you basically would not need it there - but yet we come here back to the above reasons for yes : )

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