Digital Modeling

William Vaughan

This book covers the very basics into introductions of 3D modeling and briefs over some more intermediary concepts.

In the foreword, the author stresses the importance of thinking positively. Thinking in terms of “I have everything I need and know all I need to know now to do what I want.” It's important to not get into believing there's always a secret technique or tool to make things easier and faster. It may be true, but you'll discover it in time as you work. Just do the best you can now with what you know now!

I know I tend to get bogged down into thinking “This must be a horribly slow way to accomplish what I want, there must be a better way?!?” and sometimes there just isn’t. And sometimes there is and you’ll discover it as you push on! Sometimes there is but you don’t discover it until much later.

Production Pipeline

Although not about modeling, it's interesting to learn about what modelers are expected to do on a creative project. What other roles are, know the job names.

There are 3 main phases - pre, pro, and post production. A single model job doesn't have to go through the whole process, but some projects might depending on what's needed.

Preproduction - a dirty creative phase where ideas are rapidly tested and changed. Focuses on uglier assets to get the feel of something instead of spending weeks perfecting something that may change.

Proproduction - Stuff actually getting made. A layout is set, work that needs to be done is defined, time to make stuff.

Modeling - A 3D model is made. Either by starting with a box, or starting by sculpting (which will need to be retopology-ed into a better mesh for UVs and rigging). Purely, this stage doesn't do any UVs or rigging, but should prepare the base mesh for those stages. Understanding those stages helps you know how to prepare the models.

Rigging - Bones and other deformation tools are applied to the model so that controls can be made available to the animators. The only goal is to create a rig that's flexible enough for the intended animations.

Scene Setup - Prepares the 3D scene by filling it with assets and props. Determines if new tiny models are needed to complete a look and feel. Takes a holistic view of the scene in progress.

Texturing - Materials and textures are applied to the model. Including ambient occlusion, bump maps, color, roughness, etc. Importantly, also does the UV unwrapping.

Animating - Everything so far comes together briefly and the animators try to create key sequences and poses. A suggested set of stages:

  1. Layout. Animations done using stand-ins.
  2. Blocking. Animations made with low quality roughs of the models or segmented models (which are way easier to pose without causing tears and problems)
  3. Facial animation and lip sync using final models.
  4. Final pass. Secondary animations, offsetting the timing, double check for visual errors.

Audio - Audio artists work with the animators to figure out what sfx should be going on based on the animations, the model's materials, everything.

Effects - Focuses on things categorized to VFX (explosions, particles, magic effects) and things like hair and fur.

Lighting - Taking everything so far, lights are placed into the scene to produce the right (literally) lighting and feeling/mood. Helping setup lights for the rendering process.

Rendering - Not just hitting the render button! Thought goes into placing different assets into different render layers and having multiple passes for the same scene so that compositors can assemble them with as much control as possible. They have access to multiple rendering hardware devices and need to split up the entire rendering task efficiently to make best use of the machines.

Postproduction - Slap it all together and #ShipIt.

Compositing - Putting together all the bits from the render layers stage and altering parameters to produce the best results for the needed design goals. Depending on the workflow, can be a more simple assembly or layers or more complicated where light colors are changed during this time.

Audio - Good audio is so important. Adds at least half of what you experience in anything.

Preparing for Modeling

Reference. Everything. Learning how to use references helps out a ton, and the best way to learn how to use them is to literally just start trying to use them. Finding references, figuring out which work well for what you need and which don’t. Even made-up imaginary things can be built based on real things, and it’ll only help the entire piece make intuitive sense.

Observation. This kinda ties in with learning how to use references. Refs are not meant to be copied 1:1, learn to infer from them. Study what about the reference gives the content that feel and sense you’re looking for? Break it down. Like when studying a game to break down its game design, it’s a poor idea to simply say “I like this game, I’m going to copy it.” What do you like about the game? What mechanics support the fun parts? Which detract? When it comes to 3D modeling, ask questions about how the object exists. Does it have hidden gaps? Is it all one piece, or segmented?

Warm-ups. Prior to modeling, visualize the object you’re trying to model (or take a simple object) and visualize how you’d model it.

Gathering References

A special tip for when you’re lucky enough to take reference photos literally for modeling. When you have many photos of the same object, toss them into GIMP and rotate/scale them all so they all line up (if it’s like a profile and side kinda shot). Creating a collage makes for super handy 1-image to display reference sheets.

Model Fundamentals

There are 3 core types of models. Polygonal models are made up of vertices, edge, and polygons. NURBS surfaces are networks of curves with smooth surfaces between them. Subdivision surfaces are like a hybrid, made up of polygons, but take advantage of some NURBS smoothing tools.

Nurbs Stands for Non-Uniform Rational B-Splines. A smooth mesh that’s defined by a series of connected splines (polynomial (math) curves). Transformed into polygons at render time. Used for CAD software, and long ago for organic forms (now subsurface meshes work better).

Splines are curves in 3D space, defined with 2 points (a start and end). Bezier curves are a form of spline. Control points along the spline can modify the curve easily. Splines can be patched together to form a 3D mesh plane, extruded, or cloning/duplicating objects along the spline.

Modeling Methods

Build Out - Processes of building 3D mesh quite literally and directly. You direct where each polygon will go and the entire mesh is built starting from one starting polygon/point. These tools are really good for very custom designs or retopology.

Primitive Modeling - Combine or start with multiple primitives (boxes, spheres, cylinders, cones, etc.) and modify them until done. Very handy for hard models which are often very easy to break down into these primitive shapes.

Box Modeling - Start with a primitive (usually a cube) and extrude from it to form the mesh. Similar to primitive modeling, but the difference is extruding modifying from the one primitive instead of just slapping on new primitives. Popular and used for organic shapes pretty frequently (with a subsurface modifier).

Patch Modeling - Using Nurbs/splines to create mesh. The mesh is formed from the splines combining together to form the surface. Popular for CAD, but it’s a cool tool and can be great for clothing and characters and all! Worth looking into.

Digital Sculpting - A sculpting tool (sculpting in Blender, ZBrush, etc.) is used to create an extremely high poly mesh (millions of polygons). It’s gained a lot of popularity because the artist doesn’t have to fret about the topology of the polygons - sculpted meshes are unusable for games and rigging because of the polycount, so topology doesn’t matter. Additionally, the HD mesh can be used to bake textures in a nearly automated process and then applied to a normal mesh (made using other methods) such that the details from the HD model will carry over!

3D Scanning - Real world cameras captured data visually and interpret it into a 3D mesh. A contact scanner is a tool that has to physically touch a surface to interpret it into 3D. Noncontact scanners work visually.

Textures and Animations - Mesh can be made via textures (using heightmaps) to generate terrain or surface deformations. All instances move vertices and it’s not limited to visual effects like bump mapping, which simulate a high detailed, high poly mesh by adjusting how it gets rendered. Ack! You can use bones too! Bones are normally just for animation, but instead you can use them to deform a mesh (like a hose) much more naturally.

Dynamics - (Dynamic refers to any simulated 3D system.) Using simulation systems to deform a mesh, save that deformation, and use it for other purposes. Like modeling a flat cloth, draping it over a table using a simulation, then saving that mesh with its natural looking bends and creases.

Professional Practices

Just a collection of modern professional goals, terminology, and guidelines.

Organization tips.

Clean Models

Tips on how to create clean models - models that have a low polygon count and a good topology.

Polygon Count - refers to the number of polygons in the mesh. The fewer polygons used means fewer vertices, which means it’s much easier to paint weights, rig the mesh, have it deform in a more predictable way, assign UVs, render, and more. Real-time rendering (like games) especially prefers lower poly counts.

Poly count really refers to the model’s triangle count. Although graphics processors used to be designed to handle a variety of face formations, there’s been a push to move to just using triangles. Blender now-a-days will count actual triangles of the mesh even when the mesh has 4-sided polygons. Avoid creating n-gons (5 or more sided polygons) which forces the modeling system to determine how to break it down into triangles which might be done poorly. In general, define the triangles yourself. Subsurfaced faces will also multiply the mesh and quickly balloon polycount numbers.

How much is a good poly count? Depends on how the model will be used. Basic rule of thumb is “just enough to have the mesh work for what it needs.” Things that tend to require higher counts - close up, well lit (not dark or shadowed), how much it will bend and deform, and how many angles will the object be seen from. For example, although hands are smaller than a forearm they will deform in many ways and require more faces.

A consideration is to keep several versions of polycounts of the models on hand.

Topology - (aka polygon flow or poly flow) refers to how the mesh is constructed. Good topology is easy to select, manipulate, build, and sculpt.

In general, focus on giving a model edge loops. Edge loops are edges (connecting lines from one vertex to another) that form a single continuous loop. Makes selecting easier and tends to deform well, especially for facial muscles which kind of work like loops too. It’s not a one-all fix and too many edge loops can cause pinching. A line of thought is to limit the model to only using quads which will naturally encourage edge loops.

Polygon flow refers to how polygons connect to one-another across the surface of the mesh. This isn’t something to watch out for, but rather a design decision if you realize you want some polygons connected that currently aren’t (to form good edge loops). A tool that spins edges around to change the flow can be helpful! The cool has tons of different names like SpinQuads, Flip Edge, Spin Edge, Rotate Edge, etc.

Four Sided Polygons are a constant goal over using triangles especially for organic models. They deform better than triangles and especially n-gons. However you will come across times when the mesh basically needs a triangle in order to work at all. A solution is to create a diamond-shaped polygon. One vertex points north and the 3 others are all south.

Rule of Three refers to giving joints 3 edge loops/segments - 1 right on the deformation joint and then 2 surrounding it to support the mesh. Ideal for things like knees, hips, fingers, elbows, shoulders.

Preparing for Production

A guiding list of principles to go over before releasing the model into the world or the rest of your team.

UV Layout suggestions.

Rigging suggestions.

Polygonal Modeling

The hardest part when given an object you want to model is figuring out the most streamlined way to create the mesh in an organized, clean manner. The book goes through a case study of creating a special soccer ball used for the 2010 world cup which has a really unique seam pattern. Intuition suggests starting with a sphere primitive or modeling the seams from curves, but both of these will end up being difficult to create a clean mesh from.

Mr. Vaughan discovered an unorthodox approach where he started with a tetrahedron (like a 4-sided die), suggesting that great solutions can come from trying new things. The steps went as follows:

  1. Breaking down the shape into its pieces, observing it, seeing how the object works.
  2. From a starting tetrahedron, split it into the 2 main bits: the tips and the sides (the ball is made of 8 shapes, 4 sides and 4 tips). Subdividng the mesh can help create equal sides.
  3. Clean up the subdivisions and reduce the mesh back to simple/few faces. Still very flat.
  4. Replace triangles at the tips with diamond 4-sided polygons, introducing new vertices and leaving a center vertex.
  5. Break down the sides similarly, connecting the tips together with freshly cut edges.
  6. Add new edge loops around the tips to increase the number of polys used by the sides so that it roughly matches the size of the polygons on the tips.
  7. Assign the sides to separate vertex groups and the tips to 1 group. This will help make selecting them later so much easier.
  8. Subdivide more, and use a special spherical deformation so that the mesh tries to fit a spherical shape.
  9. Assign more polys to the tips so they share a roughly similar area to the faces.
  10. Create the seams on the ball by beveling each side and tip.

Very interesting! My takeaways are listed in the cool tips section.

Subsurface Modeling

Although the last chapter also used subsurfaces, this chapter uses them more?.. Seems like the distinction is modeling with a mesh with a subsurface modifier on it (this section) as opposed to subdividing to create new polygons only when needed.

A common issue when working with subsurface modifiers is that every bit of mesh is smoothed meaning desirable hard edges and corners are totally lost. The solution really is to introduce hold segments - edge loops surrounding the nearby corners (on both sides) so that the subsurf smoothing doesn’t over-smooth those corners! I always worried this would introduce an unnecessary amount of new polygons, but I guess it’s standard professional practice! I do wonder what the thought behind doing this over using edge creases is.

Remember to practice preserving edge loops and forming quads. This may mean introducing new cuts to bridge corners instead of making a bunch of triangles.

Modeling a Realistic Head

The top 2 popular methods is either box modeling or edge extending. I prefer box modeling - working from a rough head shape then into details, as opposed to working details-out via edge extending. Edge extensions are a teeny bit easier to use only because it’s obvious when verts are in the correct spot or not as opposed to working more artistically with defining details.

When using a reference, mirroring it down the middle is a good idea for building the initial mesh, but your creature should have asymmetries by the end of it all.

Eye Tips

General Tips

Character Building Tips

Sculpting Tips

Retopology Tips

Cool Tips

Things to do when not at a computer

Some fun ideas and exercises to practice when you’re out and about.

Modeling Tips