Maya Modeling: Polygonal Modeling Theory
Before jumping into the deep end with modeling, let's take a look at some modeling theory in the shallows.
Before we start modeling, I just want to touch on some basic but essential polygonal modeling theory. If the geometry needs to be taken into a sculpting package or animated, a clean mesh is crucial. On top of this, well-executed topology produces fewer artefacts during render time. In short, a polygon in time saves nine.
Step 1: Quads v Tris v N-gons
So what is the difference between a quad, a tri and an N-gon? Well, a quad is any four-sided face, a tri will have three sides and an N-gon will have anything more than four.
Out of the three of these, it is highly recommended that you try to keep everything in quads. Generally, they subdivide more predictably, deform better during animation and you encounter less texture distortion.
If you need to use tris, then it is best to try and hide them in places where they are less likely to be seen, such as under the groin or armpits on a character.
N-gons, on the other hand, should be a no-go zone. When subdivided, N-gons can cause pinching in the renders and can be a pain when weight-painting during the rigging stage.
Taking a model that is predominantly made of quads will also transfer better to packages such as ZBrush and Mudbox.
Step 2: Uniform Geometry
Uniform geometry means that we are trying to keep our polygonal faces as square-like as possible, and space them as evenly as we can across the surface. Doing this makes weight painting at the rigging stage easier and leads to better deformation during animation. You will also get less distortion when applying textures, although the importance of good UVs will also be a factor in this.
To help you get the geometry uniform, Maya has the wonderful Sculpt Geometry tool. Setting its Operation to Relax should allow you to iron out the edges.
Step 3: Edge Flow Topology
Edge flow topology is the direction in which our edges are flowing. Sounds simple, but controlling the flow can be a tricky affair.
If you are aiming to model a realistic character, it is best advised to study anatomy. Following anatomical landmarks and the natural flow of the muscles will give you a more realistic result if the mesh is to deform. Also, studying the skin flow and where creases occur can be a great starting point to base your edge flow on.
For characters that are more cartoony or stylized, you may have more room to maneuver but either way, I highly recommend that you get a good solid grounding in anatomy.
Step 4: Non-manifold Geometry
Non-manifold geometry is when you cannot take your polygonal object and unfold it to make it flat.
Create a polygonal cube, select any of the edges and go Edit Mesh > Extrude. You now have a non-manifold object. If this were made out of paper and you unfolded it as if it was a paper die, you would have a flappy bit hanging off it. Try and perform a Boolean operation on it and it will let you know that it is not happy in its own special way.
Non-manifold geometry can give you plenty of problems so do your utmost to avoid it. To help you resolve non-manifold issues, you can use the Cleanup tool found in the Mesh menu set.
Step 5: Every Edge Should Have a Purpose
Generally, you will start modeling from a simple primitive, like a cube, and then push this further by adding edge loops or creating extrusions.
It's important that as you continue to add extra complexity to your model, each one of those new edges or faces created has a purpose. Remember, less can be more. Knowing what to cull and how to optimize models comes with time and practice so go on, get modeling.
Top Tip 1: Study the Real World
Everything that we do in the machine is generally a representation of something that exists in the real world in some shape or form. Therefore the biggest tip I can ever give is for you to go out there and experience and analyze the real world we live in.
This is relevant not just for modelers, but also riggers, animators, lighters etc. Think about how a surface has been made: how does the light hit the object and how does it deform? Answering questions like this and more will help inform your modeling decision-making.
Click HERE to see the previous tutorial in this series.
Want to start from the beginning? Click HERE to see the first tutorial in this series.
To see more by Jahirul Amin, check out Beginner's Guide to Character Creation in Maya
and 3ds Max Projects