Easy Way to Make an Arm Model
Maya modeling: Arms
In this tutorial we continue to build our model by adding the arms.
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Introduction
So far we have a torso and the legs in place. This time we continue our introduction to modeling in Maya by adding the upper extremities. Once again, we will examine the reference I'm using, but I also encourage you to look at as many external anatomical references as possible to give you a good idea of the muscle groups before hitting the computer. I also find that it is worthwhile to look at other models, especially those built for deformation, to see if you can grab any tips or ideas on how to approach the topology.
Back to the arms, where the areas of interest for this tutorial will be the deltoids, the biceps, triceps, and the flexor and extensor muscles of the forearm. We will also pay attention to the bony region of the elbow as we did the knee. By modeling-in these core lines created by these muscle groups and bony landmarks, we should be able to get some pretty decent deformation occurring. For this tutorial, we will continue to use the reference from the awesome folks at www.3dscanstore.com. However, please note that as well as looking at the front, side and back views supplied, I have also used all the other images that come with the collection to extract as much info as I could during the modeling process. Check out what they have to offer; it's all good stuff.
Obviously this tutorial is aimed primarily at new Maya users, familiarizing readers with one way to skin the modeling cat. However, there are many ways to skin this particular cat, and I urge you to explore and experiment with other packages and processes to see what suits you best.
Core muscles of the arms
Working our way from the torso down towards the hands, we first come to the deltoids. The deltoids are comprised of three heads but we will model them in as one mass.
Then come the biceps and the triceps. Anatomically, the biceps, as the name suggests, is a two-headed muscle, but these heads come together to form a common muscle belly, which is how we will depict the muscle. The muscle inserts into the forearm but we will define the region just before then as this is where the majority of the 'bulging' occurs when the arm is flexed and the wrist is twisted. On that point, I encourage you to get familiar with how your body articulates. Twist the wrist when the arm is flexed and in a relaxed pose and you'll notice that it is that movement that creates the primary bulge that we associate with the bicep, not just flexion.
The triceps, as indicated by its name, are composed of three heads. These heads meet in a common tendon creating a v-shape notch, and we want to indicate this shape in our topology. The notch is very noticeable when the arm is extended, especially on the very lean.
Moving downwards, we want enough geometry present to hold the shape of the bony elbow that lies beneath the skin. This is created by the olecranon of the ulna. The ridge of the ulna is also visible so we will want to highlight its presence.
That will take us to the forearm, where there are muscles aplenty. Luckily, we don't need to highlight each one but we do want to mimic the twisting flow of the flexor and extensor group, which affects the flow of the skin. This will finally bring us to a nice bony landmark, the styloid process of the ulna, which sits on the pinky side of the wrist. We'll add this landmark when we come to do the hands, along with the tendons on the palmer side of the wrist, next time.
The core areas of the arm that will be of interest
Extract the arm and duplicate the torso
First we need to extract the current arm geometry from the head and the wrist. Select the faces, as indicated in fig_02 below and go Mesh > Extract. With all the objects selected, go Edit > Delete By Type > History to keep things clean and break all connections between the multiple geometries. Next duplicate the current torso that we have by selecting it and hitting Ctrl+D and then hide the original model by pressing Ctrl+H. I want to work the arm into the shoulder and the chest so select all the faces below that region and delete them.
Separating the arm and part of the torso
Smooth the arm and combine it with the chest
Select the arm and go Mesh > Smooth and then move the points around to loosely match the reference. With the Translate tool active, use Soft-Selection by tapping B on the keyboard to speed up the process of moving points. You can control the falloff of the Soft-Selection by holding down the B key and left mouse dragging in the viewport, or double clicking the Move tool to bring up its settings and adjusting the falloff within that window.
Once you have the arm loosely shaped, select both the arm and the chest region and go Mesh > Combine. With the two meshes combined, go Edit Mesh > Merge Vertex Tool and snap the vertices under the armpit together to close up the open seam. Add a couple of extra edge loops running down the arm to match the number of edges that run down the torso. To even out the edges that run down the arm, use the Sculpt Geometry Tool with the Mode set to Relax. You'll find the tool under Mesh.
Smoothing the arm and combining it with the chest region
Working on the deltoid
I'm pretty happy with the flow of the edges running from the chest region over the deltoid as it currently is. Although anatomically the pectoralis muscle inserts into the humerus, I find the edge flow in the current state creates good deformation when the shoulder is raised. This is again another time where we slightly bend the rules to suit our needs. So to bring out the mass of the deltoid, I'm just going to add an extra edge loop that runs around the point where the deltoid inserts into the humerus. How tight you have the edges will determine how noticeable you want the border of the deltoid to be. I'm keeping mine pretty light for now, as I don't want him to appear super butch.
Adding an extra loop to define the edge of the deltoid
Bringing out the bicep
Pulling out the bicep is pretty straightforward: just grab the faces in that region and go Edit Mesh > Extrude. With the new geometry, I make sure to work the upper portion of the bicep back into the chest and the shoulder region by cutting into the model with the Split Polygon Tool and redirecting the edge flow. Make sure to check the forms from all angles as you progress through and refer back to the reference.
A quick extrusion to pull out the bicep, and how to work it back into the model
The elbow and the tricep
Next, I pull out the elbow by first selecting two faces on the back of the arm, extruding them and then scaling them in slightly. At the same time, we can introduce the v-shaped notch created by the tricep. I move the points around to create the initial v-shape and then use the Split Polygon Tool to add extra detail.
To keep everything in quads, I run the cut lines through the elbow and down towards the wrist. A few more edge loops are required to run around the arm so we can start filling-out the volume of the tricep and the bicep. Add an extra edge running through the elbow also so we can use it to maintain the form during flexion of the arm. You can push in some vertices to create the elbow pit in a similar fashion to how we created the knee pit. If you compare the topology of the leg to the arm, you'll notice how parts repeat themselves. Just as nature repeats itself when it is on to a good thing, so can we.
Creating the v-shaped notch of the tricep and extruding out the elbow
The forearm
This brings us down to the forearms. Luckily, we don't need to worry about the direction of the edges as the flow has been there since our initial blocking. However, we do want to define the ridge of the ulna that runs from the elbow to the pinky side of the forearm. As we have quite a few edge loops running down the forearm, we can achieve this relatively easily by simply pushing a selection of edges closer to another. (It's worth creating a tight fist with your hand to see the lines that appear on the forearm.)
After that, it is a case of checking the forms against the reference and making any further tweaks. I ended up adding a few extra edge loops around the arm to even out the faces and a loop around the elbow to make it slightly sharper. You could also define the brachioradialis muscle at this stage if you so desire. I think I'll leave it here for now and will make that decision as we approach the final hurdle. Once you are happy with the arm, merge the region back into the main mesh. See you next time for the hands and feet.
Pushing the edges together to create the ridge of the ulna bone and moving points to create the elbow pit
Top tip: Use lights as you model
As I model, I like to pop some lights in to see how the forms are building up. This is a great way to check for any anomalies that you may not generally see with Maya's default lighting. First, I go Create > Lights > Directional Light and in the Attribute Editor I enable Depth Map Shadows, punching the Resolution to the max. Then I create an Ambient light and set the Intensity to something like 0.25.
In the Viewport settings, go Lighting > Use All Lights and also enable Shadows. Still with the Viewport settings, scroll to Renderer and enable Viewport 2.0. Open up the options box for Viewport 2.0 and enable Screen-space Ambient Occlusion. Leave the Ambient Light as it is but play with the orientation of the Directional Light to see how it affects the model. It's worth playing around with the shaders also to see how the model reacts to the light; try a Blinn for example.
Using lights to check the integrity of the modeling and for any anomalies
Source: https://3dtotal.com/tutorials/t/maya-modeling-arms-jahirul-amin-character-human-anatomy
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