Organic Modelling Tips and Tricks

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TIPS AND TRICKS FOR ORGANIC MODELLING

Jul 18, 2012

Improve your creatures and characters with expert advice on

creating organic models from Glen Southern.

Over the last 20 years, 3D modelling has come a long way. I say 20 years because for a lot ofpeople their awareness of 3D modelling was first sparked when they saw animated 3D creatures

in films such as Jurassic Park.

Modelling 3D creatures and characters is now a recognised career and spans many different

sectors, including games, film, broadcast TV, web, print, advertising, marketing, medical and so

on. As with most things these days, there are many ways to get any given job done, and just

knowing one tool isnt always enough.

Organic 3D modelling can use subdivision surfaces, voxels, DynaMesh, retopology tools, normal

maps and a whole list of other features and tools. Understanding where to use each one and for

what task can be confusing until you understand what they can do for you, so read on for my

collection of tips and tricks.


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01. Brush up on your drawing skills

Understanding real-world anatomy is crucial for an organic modeller

A lot of character and creature modellers are also accomplished 2D artists. Its a logical

progression from concept sketch to 3D model, so it makes sense to try to work out your intended

subjects anatomy on paper first. Most concept artists have to do turnaround images that show a

character from several angles or perspectives. If youre asked to model a dog and you dont

understand how the bones in a dogs (or any quadrupeds) leg fit together, then the whole model

will be unconvincing. Take your time learning how bones fit together in nature. Understand how

muscles attach to the bones and how they move and slide together.

02. Enrol in a life drawing or anatomy class

Life-drawing skills can very quickly be incorporated into fantasy creature modelling


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If youve realised how important good anatomy skills are to the organic modeller, the next step is

to get some experience. Start with a Google search for reference material and maybe a few books

with good diagrams of anatomy. Begin to look at each muscle group and understand how that

works and interacts with the next. To go one step further and really push your skills, you can

enrol in life drawing classes. Once youve trained your eye and youre getting familiar with

anatomy, youll notice an immediate improvement in your modelling and sculpting. Most

universities run regular life classes and a lot of large studios arrange classes for their artists.

03. Consider form and volume

The model needs to work from all angles form and volume are everything

Two big mistakes modellers make are adding too much detail too quickly and not getting the

form and volume correct on certain parts of the subject. Whether youre box modelling or

sculpting in 3D, one of the first things you need to achieve is the overall shape of the character

youre making. If you nail the silhouette (form), then invariably the volume will be right. For

example, if you were to model an arm, which is roughly speaking two cylinders, there would be

much more bulk in the biceps area and the forearm than there is in the wrist area. The overall

shape needs to be accurate from all angles. If you start to model details in the hands at this stage

it becomes harder to focus on the overall form.


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04. Edge loops and topology

Flowing

edge loops and good topology are crucial for rigging and animation

Once youre actually modelling your desired character, there are a few technical rules that you

may need to learn. When using subdivision modelling to create a model its essential that you

have good edge flow in certain areas of the mesh. This flow often mirrors real-world anatomy, so

this is where your newfound skills come in handy. An edge loop is basically a continuous ring of

polygons that follows a specific path around a model. For example, the muscle ring around an

eye that makes the eye open and close or the line of polygons that run under the chest, defining

the pectoral muscles. Important loops are the shoulder area, the mouth, the hip and so on. This

matters most if youre planning to rig the model for animation. A poorly made model is hard to

rig and deforms badly when youre animating it.


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05. Subdivision modelling and HyperNURBS

Switching between smoothed and unsmoothed during modelling is essential

Subdivision modelling is a modelling technique that smooths out a mesh by dividing and

rounding the polygons based on a set of algorithms. Each polygon is divided into four and

rounded off. The higher the subdivision level, the rounder and smoother the mesh looks. Most

3D programs enable you to subdivide your mesh and then return it to the normal level, and that

helps you keep the polygon count down while refining the look and form of the model. There are

many ways to subdivide a mesh but often the underlying maths is the same. For example, ZBrush

uses the same method as Cinema 4D, which calls it HyperNURB Tags.

06. Quads, triangles and ngons

Use quads where possible, triangles if you have to and no ngons


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Generally speaking, try to model in quads. Quads (quadrangles four-sided polygons) are

predictable and subdivide in a clean way, leaving less chance for bad artefacts at render time.

You can use triangles for certain modelling jobs and game engines generally convert a mesh to

triangles at render time anyway. However, if you get into the habit of using quads youre also

modelling in triangles when each quad is split in half (a mesh with 1,000 quads can be converted

to a mesh with exactly 2,000 triangles at the click of a button). The one to avoid if possible is the

ngon (a polygon with more than four sides) these can cause problems in some programs and

lead to issues if theyre subdivided. Theyre used in lots of modelling situations, but as a

character modeller the ngon is not your friend. Avoid them!

07. Box modelling or point-by-point?

A

combination of box modelling and point-by-point modelling is needed for most projects

As an organic modeller, youll need to learn as many techniques as you can. Modelling with

polygons can mean box modelling or point-by-point (or edge) modelling. The trick is to become

proficient at both methods. Box modelling is so named because you start with a basic primitive

shape (a box), and refine the shape by adding splits and cuts. Point-by-point or edge modelling is

where you add more geometry onto existing polygons by extruding or stringing together points.


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Learn both methods, and learn how to do them well. When modelling a head you may like to

box-model the overall shape, but then refine an area such as the ear by extruding polygons to

suit.

08. ZBrushs DynaMesh

You can create amazing characters and creatures by using DynaMesh, and never have to work

outside ZBrush

A relative newcomer to the digital sculpting world is DynaMesh, a modelling process found in

ZBrush. ZBrush uses subdivision modelling at its core: when you pull out part of a model,

sometimes the underlying polygons become stretched or elongated. DynaMesh solves this by

remeshing the model on the fly. This is revolutionary you no longer need to consider whats

happening to the polygons in your model as ZBrush is taking care of it in the background. You

can sculpt almost anything and focus purely on form and silhouette. This method doesnt respect

the rules about edge flow and good topology, though, so thats where retopologising comes in

handy.


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09. Retopology tools

Using DynaMesh means you can focus on the modelling and think about the polygons later

Models in a voxel-based program can be exported for further sculpting or retopology

If you made a model with no regard for the underlying topology it would be impossible to rig or

animate that mesh. To solve this issue, programs such as Maya, modo, ZBrush, 3D-Coat,

TopoGun and many more now have tools to enable you to create a new base mesh with edge

loops and edge flow to suit your needs. This goes back to the rules about modelling for

animation and creating good loops around areas that will deform the most. Retopologising means

effectively rebuilding a well-constructed low-polygon model over the top of a highly detailed

sculpt, and comes at the end of the modelling process rather than the beginning.

10. Use normal maps

Using normal maps can enable you to use lower polygon models and still get a high-end look


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Even with the more powerful CPUs and GPUs of today, theres still a limit to how many

polygons can be moved around without lag or stuttering. To get a high level of detail into games

with only limited polygons, you can use normal maps and theyre not limited to games. If your

mesh has UV co-ordinates you can extract a normal map and apply it to the low-poly mesh,

giving an approximation of the detail seen in the high-poly mesh.

11. Voxel-based modelling programs

Models in a voxel-based program can be exported for further sculpting or retopology

Some voxel-based modelling programs, such as 3D-Coat and Sculptris, enable you to sculpt

volume by adding triangles. This can be a great way to build up complex organic forms and

structures, and you dont have to focus on topology or edge flow. The end result can be

retopologised for animation in the same way as any other mesh. Voxel-based modelling is

sometimes overlooked, but it can be a great addition to your organic modelling toolbox and is

well worth the time spent learning how to integrate it.

About the author

Glen Southern is afreelance 3Dartist with over 15 years of experience in film, TV and game.

Hes the owner ofSouthernGFXcreative services
http://southerngfx.co.uk/http://southerngfx.co.uk/

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Organic Modelling Tips and Tricks