Modeling a Torso One Meatloaf at a Time

I'll soon post a tutorial that uses morph targets (blend shapes) to fake muscle deformations on an animated character. For that excercise you'll need a character (or a chunk of one) with muscles that take well to morphing. So how do you make sure your character will morph well (or animate well for that matter)? The main thing is to have enough detail in the right place on the surface of your character - and that detail needs to follow the natural flow of the muscle beneath it as closely as possible.

One way to accomplish that is to cook up a little meatloaf.

Fig 1) Typical meatloaf, or loaves - and a big bag 'o muscles. Using another model as a template.

What I mean is, take a very primitive muscle-like shape, or meatloaf, duplicate it a bunch of times - and build up your model by positioning those loaves where actual muscles would go. Do you need to build every muscle for most projects? Not even close. Think of what your character will be asked to do - then check the references we'll talk about below to replicate only those muscles that seem to be the most common anatomical landmarks for the poses you'll need.

The actual process of building a character this way ends up being fairly easy and intuitive - and since there is so much in modeling and animation that is anything BUT easy and intuitive, it's nice to fall back on something simple - which isn't to say this won't take awhile. The best thing about this method is that you'll naturally stumble onto answers to all those weird anatomical questions like...what in the heck forms an armpit anyway, where exactly do I put the navel, and is the abdominal "six-pack" really an "eight-pack?"

Now, there are many ways to do just about anything in modeling and animation - and you may be one of those gifted modelers who can take a cube, pull a few points, and presto - you have a great, animatable character with perfect edge loops. Those folks can jump to the next tutorial - or better yet - try it this way just once...

So, what do you need at hand before even attempting this???

1) Profile and frontal drawings (at least) of your character:
A bird's eye view is helpful as well. Or - if you happen to have a more or less humanoid model to work with you can pull that in, give it its own layer and set it up as a reference or template so you're not constantly selecting its components by mistake. I started with my elfin pirate girl. Okay so that means that in this case I'm building a male torso with a female frame - no worries - all you're looking for here are general boundaries to guide you - sort've like a bag you're filling with muscles. Ewww. After the bag is filled, we can make overall adjustments as needed. (Okay, so this never worked for Michelangelo whose female sculptures tended to look like men with breasts - but he didn't have Core i7 and a lattice to work with either...)

I also find it helpful to create the body cleavage with a plane (grid) that I scale, subdivide and shape to the profile of my character. The body cleavage serves as an anchor point for the muscles of the back and chest and also provides a nice clean row of vertices to snap in X on the center of our grid before mirroring the half torso we'll build. The body cleavage is that sort of stringy thing extending north and south of the torso in the pics.

2) Anatomical reference:
I'm lucky enough to have a yoga instructor for a wife. Not only can she be easily molded into most shapes I need - she has lots of great books lying around that deal with body structure and movement. A really good one is Andrew Biel's, Trail Guide to the Body. But heck - we easily live half of our lives on the internet anyway - just do a quick image search on torso and you'll find more than enough reference pics to get started.

I recommend medical reference drawings - both with and without skin, male & female, in various poses. To build a torso with muscles that morph well - you'll want to build it with all of the muscles tawt or slightly bulged - we'll smooth and flatten them as necessary in the next tutorial. Since our bodies don't naturally work well with all of our muscles tawt and bulged - the skinless medical references are very important to see where these muscle fellows hide out - where they start and end, and which ones tend to roll underneath other muscles and disappear in certain poses.

Body building photos are helpful if nothing else just to show you how much variety there is in human musculature even though we all start out with the same basic set of muscles. Don't get hung up on little muscles that were never meant to be big muscles unless your character REALLY requires it. So...it's helpful to have reference on hand of, well, regular folk. Depending on which muscle groups body builders choose to work - and which pose they choose to take - it's easy for a modeler to get mixed up on what the most important muscular and skeletal landmarks really are - so those regular folk pics really come in handy.

3) A meatloaf:
Okay this is easy - start with a cube, subdivide or smooth it and work it into a simple "loaf" shape fig. This will serve as your muscle primitive. I've built the torso in this tutorial mostly with two forms of the same primitive in fig 1 I've also used a few planes (grids) as filler between muscles when necessary - and even an uncapped cylinder as an anchor for a lot of the torso muscles.

Now for the fun part.

Checking your anatomical and model references - duplicate, scale, orient and place the loaves as if they were actual muscles. Don't go for perfection with this pass - just get them more or less in place and oriented. HINT: Get used to having your "move" or "translate" properties window open - you'll want to switch between global, local, average vertices, rotation axis, etc. quite a bit as you manhandle your muscle loaves into place. Also - you don't need to duplicate the first loaf every time you need to start a new muscle. You'll find, as you go along, that many adjacent muscles share the same basic shape and orientation. Get one the way you want it and then duplicate that one to start building the next.

I've assigned different colors to adjoining loaves for the most part - this isn't necessary, but it can be helpful as an "on-model" reference to the boundaries of the muscles once they've been merged into the final model. That can help you fine-tune the muscles later on.

It's also helpful to place groups of muscles into separate layers if your modeling package of choice allows this. The layers give you a quick way to hide any group that gets in the way of the area you're currently working on.

Once You've Placed Your Loaves

Okay - now it's time to look more carefully at where all of these muscles need to attach. Take a small group of loaves - the deltoid muscle on the shoulder isn't a bad place to start. I've used 3 different loaves to build this - not exactly anatomically correct, but it gives me the landmarks and detail I'll need to indicate bulging later on. I've hidden one piece for the following exercise. The recipe for combining all of these separate pieces generally follows the 10 steps below:

steps one and two

1) Locate the "dominant" muscle of the group. This tends to be the muscle that determines the overall shape or direction of an area so your anatomical references are important. Often (but not always) this muscle closely follows the direction of the bone beneath it.
2) Select and delete the overlapping faces from your muscles.

steps three and four

3) Now, where possible, use your polygon split or loop insert tools to add edges to your sub-muscles that correspond as neatly as possible to the edges on your dominant muscle. We want to create new edges here before deleting the old ones so that we retain the shape of the sub-muscle as much as possible.
4) Align existing rows of vertices or edge rings as long as this doesn't compromise the shape of your sub-muscle to any large degree, then elect and delete unnecessary edges and vertices from your sub-muscle (components that don't correspond to edges on your dominant muscle).

steps five and six

5) Set your application to display vertices on your dominant muscle (not always necessary for using point-snapping tools - but it does give a better visual reference as you work). Activate point-snapping in your modeling package.
(Hint: Check your move or translate tool settings and make sure movement on all axiis are set to either global or world you'll want your vertices to move freely in world space for snapping to work properly).
6) Point-snap each vertex on the open edge of your sub-muscle to the corresponding vertex on your dominant muscle. When finished disable point-snapping (very important), and reset your move or translate tool to vertex or average vertices to give a more localized transform for fine-tuning your model.

steps seven and eight

7) Combine or merge (depending on your application) your dominant and sub-muscles so they now can be selected as one piece.
8) Select all the vertices at the edges of your muscles. Merge or sew these vertices together.

steps nine and ten

9) Select all the edges where the two muscles meet. Merge or sew these edges.
10) Begin fine-tuning your new model piece to fit to the next section of your model.

That's basically it. Follow those same ten steps in that order for every muscle group until you've built your entire half-torso.

Front Tors

Front of torso with abdominal loaves being moved and connected into position. Note that it's best to get your muscles connected before you spend too much time making sure all of your polygons are quads. You'll find you'll need to re-route many of your edges once all those little loaves are in place anyway.

torso back

Building up the back. Note that I've used grids and cylinders as primitives as well as the muscle-loaves. Use the primitive that gives you the easiest jump-off point in modeling any model piece that you need. The important difference between this modeling exercise and many others is that you are starting with individual pieces (as opposed to one primitive you simply mold into shape) and this not only makes you more "aware" of the individual elements which make up the human body, it also gives those elements natural flow lines automatically.

Issues that will arise in this exercise:

Not all the muscles are really connected to each other - especially the muscles of the abdomen.

If you run into large flat areas - go ahead and use another primitive as a base. In the case of the "barrel" of the torso - I used a cylinder then hung the abdominal muscles off of it like pictures on a wall. In this case - the cylinder became the "dominant" muscle as I connected in all of the smaller muscles. Once all the muscles were properly merged I used a lattice to adjust the overall shape and scale of the torso.

Not all of the edges align neatly with each other when I attach. God forbid - I've got triangles here and there!

We really do want quads. Despite your best efforts you will likely end up with a 3 sided poly here and there. When they happily touch you can often stick a vertex on the common edge - instantly you have two quads! Try to hide triangles in obscure places if you can. When you can't, well the smoothing operations in 3D applications are getting smarter all the time - If you were going to smooth anyway don't fret too much - they're not a death sentence for your model anymore. What you REALLY don't want are n-gons (polygons with more than 4-sides). Break those into pieces - even if it leaves you with a triangle.

Hey - I'm bothered that this thing doesn't look all smooth and neat like I see in the training books.

Well - the human body is a living thing. It's not all smooth and perfectly aligned - a little "tasteful" randomness can actually help sell it. And heck, you can always use your sculpt tools to smooth and spread vertices wherever you want. Keep in mind the difference between the bumpy-looking multi-colored torso pictured in this tutorial and the flesh-colored one is only one level of smoothing.

Hey - is this torso finished?

Not by a long shot. Think of the half-torso you can download from the bottom of this tutorial as one more primitive to add to your modeling tool box, like a torus, a cube or any other primitive. It isn't perfect by any means, but, like any primitive, it's an easy point to start from when building other torsos.

How do I use the attached zip?

The zip includes the half-torso and its material file below. Unzip and import these into your favorite modeler and have at it. Some modeling apps have a rough time figuring out proper normal direction on a model whose pieces were negatively scaled which is why I've only included half of the model. This should be a plus since it allows you to add or subtract from the torso as you like while keeping the symmetry as long as you need to. When it comes time to create the other half - simply make sure the center edge vertices are snapped to the center of your workspace and then duplicate it with a negative scale (I created this model to look forward along Z with Y being "up." Check that all of your normals are pointing outward - then attach the two halves the same way you attached all of the muscles above.

What then?

Feel free to use this torso as a template or primitive for your projects. Add to it - make it better - add forearms and legs and such. Tell us what you did - upload your improved model back to the site with your tips, tricks, etc. and let's see what we can all build together! By all means, enter your work and method in the Animate This! tutorial challenge! You'll not only get points toward the Intel Software Network Blackbelt program - the five best tips, tricks, and tutorials entered each month will receive a $100 voucher for downloads from Gnomonology!

Download the torso model here!
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