Low poly base mesh, what are you priorities?

bitinn

Hi all,

I am looking at wiki page for Topology and Base Mesh while trying to create a female base mesh for my personal project. I am very new to modelling and want to hear your opinions.

1. What sorts of details you always put on your base mesh?

2. For a low poly base mesh, what would you happily omit?

3. If I aim to "model then sculpt lightly", instead of going the "high poly then retopo" route, what special care should I give to my base mesh?

Below is my current progress: I think its quad size could be more even, and it is missing proper deformation joints, and there are a few poles/triangles I think need sorting out, and the ratio of arms are probably off...

Please kindly let me know if I have screw up something (or everything).

musashidan

The priorities are clean deformation, and silhouette. The shoulder/pelvis are usually the trouble areas when skinning. Your shoulder and underarm topology look like they wouldn't deform too well. There is a quick rig toolset in newer versions of maya. You should make use of it when researching topo solutions. Trial and error is often the best learning resource. Have a look on the hippydrome website for some excellent character topology examples.

bitinn

musashidan said:

The priorities are clean deformation, and silhouette. The shoulder/pelvis are usually the trouble areas when skinning. Your shoulder and underarm topology look like they wouldn't deform too well. There is a quick rig toolset in newer versions of maya. You should make use of it when researching topo solutions. Trial and error is often the best learning resource. Have a look on the hippydrome website for some excellent character topology examples.

Thx for pointing them out! Definitely going to try the quick rig tool and fix topology.

bitinn

I have been working on this base mesh with quick rig tool. While I still have a lot problems to address, I find myself not certain about one concept:

I understand having good edge loops are essential to good deformation. But I can see many strange deformation are caused by bad rigging / bad skin weighting / impossible angles. So how should I know if my base mesh is good enough and I should fix skeleton and skin weight instead?

PS: I am using Hippydrome as a guide (and I know my character topology is nowhere near it), but I also want to keep my base mesh relatively low poly (around 2000 if possible). 

I 

Eric Chadwick

Look again at the topology examples, paying special attention to the FLOW of the edges, how they curve through the bendy regions of the body.

Understanding of good modeling flow for deformation also requires a decent understanding of deformation itself.

So yeah, you'll need to practice weighting too. It's not really all that complicated, you can get by with a simple rig and simple blended weights. Just takes practice, like anything else.

bitinn

Eric Chadwick said:

Look again at the topology examples, paying special attention to the FLOW of the edges, how they curve through the bendy regions of the body.

Understanding of good modeling flow for deformation also requires a decent understanding of deformation itself.

So yeah, you'll need to practice weighting too. It's not really all that complicated, you can get by with a simple rig and simple blended weights. Just takes practice, like anything else.

Thx for the pointers! I will work on them. I think the steps are:

- Try to fix the model edge loops before subdivision.
- Use quick rig with custom skeleton and skin weight.
- See what's wrong and back to step 1.

And I think a hard-and-fast rule is you always fix topology first, and if you can't spot any problem, try skin weighting.

Do let me know if I am wrong...

musashidan

Yes, and after a few characters and some more experience you can skip the first step altogether. 

This is the topo I like to use for shoulders as it follows the underlying musculature nicely. The pectoral flows into the deltoid through the armpit. 

bitinn

musashidan said:

Yes, and after a few characters and some more experience you can skip the first step altogether. 

This is the topo I like to use for shoulders as it follows the underlying musculature nicely. The pectoral flows into the deltoid through the armpit. 

Thx! Are you trying to link/embed a reference image?

Anyway, here is my progress so far: silhouette, topology and rigging. I know the head size seems a bit off for realistic human, but I think she fits the stylized character I am aiming at? (see end of this post).

Also her shoulders are a bit off in T-Pose, I think it's down to skeleton and skin weight now...

Comments are welcomed.



For comparison, one of my reference, from Atelier Sophie

Eric Chadwick

Put her image behind your model, and adjust proprtions until they match. Your hands are pretty small for example.

Take a close look at the groin in the Hippydrome examples, and compare with yours. A rectinlinear grid like yours is bad topo for deformation, and also bad for sculpting.

kanga

Edit

bitinn

Eric Chadwick said:

Put her image behind your model, and adjust proprtions until they match. Your hands are pretty small for example.

Take a close look at the groin in the Hippydrome examples, and compare with yours. A rectinlinear grid like yours is bad topo for deformation, and also bad for sculpting.

Thx Eric! I think I get what you are saying about the groin topology, but just to be sure:



- You are saying they have different polygon density across the groin section.
- You are saying the vertical edges concentrate at the groin (front and back).
- You are saying the horizontal edges bend up on the sides.

I run into 2 problems when trying to fix my model:

- I don't have nearly enough edges due to my cap on polygon count (I did subdivide once and clean up some edges).
- When I try to go for the very tight lines (like the ones middle of buttocks), I end up sacrificing good silhouette due to lack of edges.

So here is what I got for now:





As for bad deformation, I am not sure if you mean the following problem. But should these be fixed using skin weighting instead of topology?

kanga

Yes that pelvic area will give you grief,
The base mesh in a ZBrush workflow isnt really super important, as long as its symmetrical (not always) and has a continuous center line. I guess its how you prefer to work. I like the freedom to determine the geometry as a last stage step.

mod edit: fixed bold!

musashidan

bitinn said:

musashidan said:

Yes, and after a few characters and some more experience you can skip the first step altogether. 

This is the topo I like to use for shoulders as it follows the underlying musculature nicely. The pectoral flows into the deltoid through the armpit. 

Sorry, forgot to paste links


And here's a character I did recently using that kind of shoulder topo:

bitinn

Thx Kanga! Given your example, are you saying my pelvic edges (horizontal ones) need to bend up more on the sides? Mines are currently about 15 deg upwards, I can see yours are almost 45 deg (even more than the hippydrome example).






As for the workflow, unfortunately I am not going though Zbrush (ie. not the high res to retopo low res route), I intend to sculpt lightly with Maya / Mudbox / 3D Coat etc., after creating a base mesh.

A side question: may I ask if you started with a naked base mesh or did you start with basic clothing?

bitinn

Also thx @musashidan for posting that reference. I did try to follow that image but mine is still lacking. Critiques are welcomed






PS: her underarm / shoulder looks weird in T-Pose, I think it has more to do with skeleton joint placement or skin weighting...

pior

Don't do the  "slouched shoulders" thing. Make the collar bones of your rig perfectly horizontal.

And better yet : Do as suggested above and overlay your references on top of your model - don't just look at them. Also a good idea is to bring in a 3d model of a human skeleton into your scene, as it will teach you things about joint placement that you will not catch by just looking at cartoony character models.

Also since you already have a temp armature thrown in (which is great, and something that more people should do while modeling), make sure to take the time to create a few natural idle poses.

kanga

bitinn said:

Thx Kanga! Given your example, are you saying my pelvic edges (horizontal ones) need to bend up more on the sides? Mines are currently about 15 deg upwards, I can see yours are almost 45 deg (even more than the hippydrome example).


As for the workflow, unfortunately I am not going though Zbrush (ie. not the high res to retopo low res route), I intend to sculpt lightly with Maya / Mudbox / 3D Coat etc., after creating a base mesh.

A side question: may I ask if you started with a naked base mesh or did you start with basic clothing?

No worries the sculpting thing in Maya is probably pretty good. I Like to have my Pelvic area slanted because I feel i get better deforms from them that way.  I always start with a naked figure because it is easier to map out by adding the costume on top, but that is just how I like to do it. Not with this figure but other characters can gain a lot of weight with the costume so you can adjust that later. Here is the thread:http://polycount.com/discussion/comment/2313651#Comment_2313651

bitinn

pior said:

Don't do the  "slouched shoulders" thing. Make the collar bones of your rig perfectly horizontal.

And better yet : Do as suggested above and overlay your references on top of your model - don't just look at them. Also a good idea is to bring in a 3d model of a human skeleton into your scene, as it will teach you things about joint placement that you will not catch by just looking at cartoony character models.

Also since you already have a temp armature thrown in (which is great, and something that more people should do while modeling), make sure to take the time to create a few natural idle poses.

Thx pior! I followed your shoulder suggestion and with a bit of skeleton update, I think her shoulder line is now decent.



However, I just don't think I can fix the underarm strangeness with topology alone, paint skin weight visualisation shows my underarm torso is under too strong an influence from skeleton arms.



As for the suggestion to have reference images in views, yep, I do have them in orthographic views. I hide them in perspective views partly because I don't want to rely on snapping to reference too much, and partly because they never line up perfectly anyway... (But I agree I should do better at following reference.)



A quick question:

- I want to try out a few natural poses as you suggested, but I can't figure out a way to duplicate the model along with control rig (or update the model without breaking control rig). Are there any tricks?

bitinn

Also thx @kanga for the suggestion on pelvic edges, I tried it and it looked better now. (Good enough? Any further tweaks?)

musashidan

For testing your skinning you just set up an animation sequence. Leave your rig in T/A pose at frame 0 and just key the rig into different poses along the timeline. That way you can scrub through and fix the skinning. Just delete the animation when you're happy to revert to the rig pose. I'm sure you can also freeze the rig or create layers but I use Max so am not familiar with such in Maya. 

Also, Maya now has dedicated corrective morph sculpting tools which are handy (but unfortunately don't transfer to UE4/Unity at the moment)

bitinn

musashidan said:

For testing your skinning you just set up an animation sequence. Leave your rig in T/A pose at frame 0 and just key the rig into different poses along the timeline. That way you can scrub through and fix the skinning. Just delete the animation when you're happy to revert to the rig pose. I'm sure you can also freeze the rig or create layers but I use Max so am not familiar with such in Maya. 

Also, Maya now has dedicated corrective morph sculpting tools which are handy (but unfortunately don't transfer to UE4/Unity at the moment)

Thx! I will try that trick.

But do you think it's a good idea to have a master rig that I can reuse on other characters (as they share the same base mesh)? If so, how can one do that in Maya?

musashidan

That's called rig retargeting. And Maya has pretty good tools to do it. I think it uses the human IK rig though so that's something you could look into.

If your characters share the same basemesh then yes, it's certainly possible. It's a very common pipeline at studios.

bitinn

Thx, using "retargeting" keyword gave me some great pointers to go on learning.

I was also looking at this video for Maya 2017 Update 3 about bake deformer tool, which looks promising.