3D (Geometrical) Modeling Fundamentals

By Ali Ismail

Sections

I - Perception

  1 - Reference

  2 - Proportion

  3 -Simplifying Forms

II - Modeling Tools

Extras

Introduction

Have you ever wanted a tutorial, you can show to beginners in 3D, or anyone who sends you a disproportionate model, a tutorial that explains basic proportions and an overview of the 3D modeling process? I am in urgent need of one, to help me in my collaboration with 3D modelers, so I thought maybe you would also like it.

You can either have a look at this tutorial, use it for instruction or pass it to any beginners or anyone who is interested in broadening his/her perspective. This article, does not go into any specific modeling details. Instead, it focuses on practices we can learn from traditional art and basic blocking methods.

After writing this, I did discover a very great article by Glen Moyes , To those learning 3D, It's an excellent article which perhaps have illustrated many points much better than what I have done here, please consider having a look at it, before or after reading my article.

Modeling Definition

To get a better grip on the general use of the term, and to easily grasp basic principles later on; it's good to know, the word "modeling" has a much broader meaning, simply described as: to represent. One common theme, that runs across all uses of the word, would be that it's an approximation. You can have a weather model representing yearly rain fall, a person who is a model of self-control, a mathematical model simulating the airflow over an airplane wing, or what we are interested in now: a three dimensional geometrical model of an object' surface.

3D modeling can be described as the process of creating a digital version of an object' surface; real or imaginary.

Perception

There's a rumor running around, that a traditional artist would make for a much better 3D modeler, and for good reasons I might add!

So, should you study 4 years in a fine arts department somewhere to be a 3D modeler? not exactly!

We, CG artists have it easy, we don't have to worry about perspective, making symmetrical objects, achieving correct form with lighting, casting shadows properly, etc. But that doesn't mean we can skip everything.

These, IMHO, are generally the things you need to know, and learn from drawing, and take with you into 3D:

1-Reference

The more you are familiar with any object/theme, the easier it will be to reproduce. Get any reference you can find. If you can see your object in person and touch it with your own hands, then all the better.

2-Proportion

Proportion, proportion and.... proportion. This was perhaps the reason for writing this tutorial. When working with junior modelers, I receive the disproportionate 3D models all the time. I usually find amazing painstaking effort put into the details, only to find out, all the main features are way too big or too small in relation to each other, with no easy way of fixing it.

How can you get the proportions right?

Any progress you will make in learning how to draw, will eventually overspill into 3D and show you the simplicity of making measurements and comparisons while looking at something.

Drawing is actually a very active process that involves thinking, you can only become fast and intuitive after practice. It goes something like this:

Let's start with an image, and how you would go about trying to copy it.

Let's start with an image, and how you would go about trying to copy it.

looking at things as triangle makes it easier to estimate the dimensions. Try also to imagine center lines.

looking at things as triangle makes it easier to estimate the dimensions. Try also to imagine center lines.

Imagine more lines and see where they are placed, which will help you identify the locations of the features.

Imagine more lines and see where they are placed, which will help you identify the locations of the features.

Start making more lines, intersections and details, you can of course choose your lines based on features in a better way than what I have done here very quickly.

Start making more lines, intersections and details, you can of course choose your lines based on features in a better way than what I have done here very quickly.

Do Comparative measures.

Do Comparative measures.

Foundation lines, points and constant measuring make it easier to create drawings which have correct dimensions.

Foundation lines, points and constant measuring make it easier to create drawings which have correct dimensions.

Exercise

Grab 2 papers, on one, draw some dots where ever you like, then on the other try to match the points you've drawn, simply by looking and making comparisons and relations between the points locations  I found this exercise at, (The Art of Drawing by Willy Pogany) Later you really should, use any image you have on the computer,and then try to draw it, the results doesn't matter now. This act of comparison alone is enough to improve the way you look at modeling.

Grab 2 papers, on one, draw some dots where ever you like, then on the other try to match the points you've drawn, simply by looking and making comparisons and relations between the points locations 

I found this exercise at, (The Art of Drawing by Willy Pogany)

Later you really should, use any image you have on the computer,and then try to draw it, the results doesn't matter now. This act of comparison alone is enough to improve the way you look at modeling.

Please note, in drawing, it could also help to know the structure of the thing you are drawing, and you could sometimes employ techniques of drawing the forms first, to make sure you get the form correctly, but I just wanted to illustrate the general concepts.

Actually the subject of seeing and perception and ways to improve it, is really vast, there are exercises such as contour and gesture drawing, drawing things or looking at things upside down! to know more ideas and concepts, you can see the following books:

The New Drawing on the Right Side of the Brain by Betty Edwards | The Natural Way to Draw by Kimon Nicolaides |The Practice and Science of Drawing by Harold Speed

Proportion in 3D

Now, for modeling in 3D, it's not exactly the same, it's closer in a sense to drawing from imagination, in 3D you have to estimate depth, and how big something is in reality, and not simply, what it appears to be in a drawing.

I overemphasized the perspective effect, but as you can see, when trying to model something, sometimes it can be hard to know how big or small one thing is in comparison to another.

I overemphasized the perspective effect, but as you can see, when trying to model something, sometimes it can be hard to know how big or small one thing is in comparison to another.

But actually, You should not underestimate the power of your brain, you have a very efficient software inside, which can be greatly improved with feedback loops called practice, which will help you make accurate guesses on the size of things, even in preceptive.

But actually, You should not underestimate the power of your brain, you have a very efficient software inside, which can be greatly improved with feedback loops called practice, which will help you make accurate guesses on the size of things, even in preceptive.

Practicing modeling, preferably with a conscious effort to improve, and checking your model with the reference at every stage, in similar fashion to traditional fine artists will improve your ability to judge proportions.

Measurement

One of the many great advantages we have in our 3D applications, are measurements:

You can use any thing you know the actual size of, such as a human figure, a coin or a building floor height, place them in the scene and compare how you model looks in relation.

You can use any thing you know the actual size of, such as a human figure, a coin or a building floor height, place them in the scene and compare how you model looks in relation.

Do you have any data on the dimensions or accurate blueprints (If you use blueprints, double check they are accurate), don't spare any details measurements you can get and put them into good use.

Do you have any data on the dimensions or accurate blueprints (If you use blueprints, double check they are accurate), don't spare any details measurements you can get and put them into good use.

Blocking Models

First things first, always start with the bigger forms and when you finish doing your best to match their size; move to smaller details. Model basic layouts to see how it all fits together, before investing effort in the final model.

Like all of Guerilla CG Project videos, This "Primitives (Blocking Models)" video is an excellent tutorial by Andrew Silke.

Vessels Basic Layout
Vessels Details

Even for this spawn character I wanted to sculpt, you can see the same layout blocks first:

Spawn Figure Layout

I had to do a layout for a small action figure, because at that time, there was no quick and easy photogrammetry tools available or a 3D scanner at hand.

Which brings us to amazing ways, to make modeling a lot easier: photogrammetry and 3D scanning. (more details in the tools section)

Photogrammetry and 3D Scanning

If you use your camera to capture a model, it might not be always completely accurate, but why not give it a try? unless you want to deliberately train yourself on modeling, if you can take photos and convert it to 3D; you should not hesitate.

Skull Art Scanned

Exercise

Get an action figure, a toy, or anything that is not reflective and has some details. place it in-front of you, touch it and and study it and start 3D modeling it; staring with a basic layout first.

Afterwards, take pictures of it and use a photogrammetry tool to generate a 3D model. Compare the results!

 

Camera Matching

Another, often neglected way, to improve the accuracy of your models, is to try to use your 3D software camera matching capabilities or simply eyeball images (match by guesswork), and directly make comparisons of the model proportions.

The catch 22 that happens sometimes with camera matching images, is: how to match an image for something you still didn't build accurately? general solutions would be to focus on background cues if they are found, look up any measurements or dimensions and use them as a base that you are sure of. Or if all fails, match few as best as you could, build something basic, try to match more, add details, match again, etc. constantly correcting and rematching, until what you have could at least match images approximately, depending on the photos you have; camera matching could be really a time consuming process. but give it a try, getting the proportions correctly is worth the effort and would save you expensive modification time.

Almost for all of my models which I want high accuracy, I attempt to match at least few images to make sure everything looks okay. Below is a car example, in which I used camera matching.

I started by modeling a basic layout model.

I started by modeling a basic layout model.

No blueprints, only some dimensions and photo reference.

No blueprints, only some dimensions and photo reference.

I tried to match my model to many images, correcting both the model and my matched cameras as I went.

I tried to match my model to many images, correcting both the model and my matched cameras as I went.

Because of the all of the different cameras, some cropped or distorted image and using a model which you are building with some guesswork, you will not be able to match the result 100%.

Because of the all of the different cameras, some cropped or distorted image and using a model which you are building with some guesswork, you will not be able to match the result 100%.

But, you can match it to the extent, that if you sent this to an art director, he can't look to one image and tell you: see here it doesn't look right, it's too big or too small.

But, you can match it to the extent, that if you sent this to an art director, he can't look to one image and tell you: see here it doesn't look right, it's too big or too small.

15 images were used, and I even tested with a simple rotation movie sequence and tried to match it roughly to see if it can pass.

15 images were used, and I even tested with a simple rotation movie sequence and tried to match it roughly to see if it can pass.

Considering I started with a model, that didn't match with the original, thus had difficulty matching the camera; a lot of work was done to get the proportions correct! but it's still worth it, it all depends of course on your time-line and the quality you are trying to achieve.

3-Simplifying Forms

Simplicity is key, Complex models are in a way a modified version of a simple form (primitive, basic model) and/or one which is combined with one or more simple forms. In traditional art, basic forms are emphasized; If you want to draw from imagination a box will do wonders for you. In reality of course, these are only approximations, but without these approximations or simplifications you will keep staring at a model not knowing where to start.

Famous Artists Course

"Form is the shape and structure of anything, as distinguished from the material of which it is made."

Quote and Image above are courtesy of Famous Artists Schools, Inc., Westport, Connecticut. Famous Artists Course Dorne et al Lesson 2 Form- the basis of drawing.

I would love to tell you, that the process of simplifying a model to 3D model it, is always simple as the one above. Unfortunately it isn't! Perception is the first and most important step, but when you need to simplify a model to decide on how to build it, you will need experience in the modeling method of your choice:

- If you are sculpting it, you will need to have a rough basic object, you will only be trying to think in terms of volume.

- Doing it in polygons, requires your consideration of topology and your basic form is going to be the face and loop.

-NURBS, will require you to come up with a way for these object to be built.

Let's try with this one

Let's try with this one

Applying a strict traditional art look at it, we will say it's a sphere and a cylinder, but is this enough? (though, for sculpting it could be )

Applying a strict traditional art look at it, we will say it's a sphere and a cylinder, but is this enough? (though, for sculpting it could be )

going a step further and adding more shapes will help understand the model more, but if we are to build it in polygons or curves we need to start thinking in those terms.

going a step further and adding more shapes will help understand the model more, but if we are to build it in polygons or curves we need to start thinking in those terms.

There are also many ways to simplify a model:

Loomis Head Recreation in 3D

All I can say at this point that perception is the most important skill for modeling. The difference between a good modeler and a bad one is (usually) seeing, which happens inside the mind through the eyes!

After knowing how to perceive and see, Its important to have a skill in a modeling tool, and be able to simplify forms to reach your desired target. I sound like I am rambling too much, but what I am trying to say is, to model quickly and efficiently, with experience you will be able to look at a reference image and visualize both the final 3D model and a simplified version in your head.

This video over here, might be helpful to see the process of simplifying surfaces and to recap some of the points mentioned in this tutorial:

which brings us to modeling tools.

3-Modeling Tools

These are generally some of the ways you will go about 3D modeling objects, currently, when displayed on a monitor; all will be using the underlaying polygonal geometry of vertices and faces, but, categorizing them this way will help you think of 3D modeling in a different light (I hope).

This is only a general overview, detailing and showing how to model efficently with these tools is a subject that would need a lot of attention.

1 - Let the Computer Do It for You

Why bother spending time on something if you can have it done automatically! even if the quality or format produced from 3D Scanning or Photogrammetry isn't exactly what you want, starting with a scanned version makes it a lot easier for you to model anything or rebuild it.

Predictably, with time, these tools are going to get better and the rig sets will be more affordable. BUT, that doesn't mean no modelers are going to be needed! if for no other reason than the fact we do design new things that only exist as a thought in our brains, how about that slimy alien in the video game you are playing or next year car model!

Now, a tool that can read your thoughts and translate it into a completely digitized model? that one would be a risk for 3D modelers to watch out for :)

Photogrammetry uses images to create your 3D model, 3D scanning uses a laser to detect a point cloud. 3D scanning is generally more accurate while photogrammetry gives you a faster and easier way to get it done.

2 - Play Minecraft or use Lego Digital Designer

Voxels are the 3D version of pixels, after all, modeling is about approximating an object, Lego or minecraft cubes represent 3D forms, albeit very crudely. But nonetheless, good practice in proportions.

A most rational way to think of a method to represent 3D models would be the following: we use squares or circles s (pixels) to represents shapes, why not use cubes or spheres (3D Pixels) to represent forms? There are obviously some problems with efficiency and the number of voxels needed to create a smooth accurate 3D model, I wouldn't exactly expect you to jump on Minecraft to deliver your AAA game character, but I included this one; to help you visualize that 3D modeling is not just about polygons.

3 - Sculpt Digitally

There are always more than one way to reach the same goal, sculpting tools offer a different way of shaping forms and adding details. You can think of sculpting as an evolution of voxel modeling, both deal with volume.

Most people having problems with sculpting usually either have to work on perception, stated in the first parts of this tutorial, or they actually haven't practiced sculpting in a conscious manner. To improve your sculpting skills you can try this:

Exercise

Start with a basic slab. And try to chisel out any basic form, a cube, a sphere or a pyramid.

Start with a basic slab. And try to chisel out any basic form, a cube, a sphere or a pyramid.

You will find perhaps, even that, is not as easy as you presumed it to be. (No cheating allowed! do not try to use a quick clip brush)

You will find perhaps, even that, is not as easy as you presumed it to be. (No cheating allowed! do not try to use a quick clip brush)

So, before putting your heart and soul into sculpting those triceps, why not make sure you know how to sculpt a box.

So, before putting your heart and soul into sculpting those triceps, why not make sure you know how to sculpt a box.

4 - Fiddle with dots and triangles

Polygon modeling, this one is the holy grail of 3D modeling, any 3D model viewed interactively uses polygons. It's the most basic and wide spread modeling method.

Instead of using a large number of points such as voxels, you can use a small number and mesh it together, and maybe use some algorithms to smooth it out (subdivision surface).

For the very basics of polygons I again recommend Andrew Silke's Video: The Polygon, and Glen Moyes' Subdivision Surfaces: Overview or just check the great wiki by polycount which contains lots of links Subdivision Surface Modeling

and you can view my quick article about modeling in polygons here. Polygon Modeling Practical Basics.

5 - Play with lines and find a way to connect them

A lot of objects can be created by simple operations on lines and curves, Although a NURBS modeling software is the best representation of it, these tools are widely incorporated one way or another in all modeling software through simple operations like, extrude, revolve, loft, etc..

I have a tutorial which you can check, that examines NURBS: Introduction Into NURBS

 

Future Tools

At the moment, there is a huge potential for any small team of dedicated programmers/artists to create a modeling software that combines various modeling and texturing tools we have in an intuitive manner. But, this doesn't change that the basics you will learn now, these foundations will still be valid in any package you use.

Extras

If you are overly "practical" and or in a hurry you can skip all the info below, but nonetheless, I chose to add it here for anyone who enjoys this subject as I do, and would like to know all what he/she can.

 

Latin Origin of the world model: Diminutive of the Latin modus, which means a measure, quantity or manner comes the word modulus: little measure. The French derived modèle from it (modelle in middle French) to describe blueprints of buildings and later miniatures which is very close to our current use.

Another definition which we should be interested in, for 3D modeling, would be had simply by replacing the word drawing for 3D modeling in Betty Edwards' - The New Drawing on the Right Side of the Brain: "3D modeling is a global or "whole" skill requiring only a limited number of basic components"

The [Very] Wise Modeling Principle

"When modeling a phenomenon, [I] understand the phenomenon you’re modeling and [II] your goal in modeling it, [III] then choose a rich-enough abstraction, [IV] and then choose adequate representations to capture your abstraction within the bounds of your resources. Once this is done, [V] test to verify that your abstraction was appropriate." (Computer Graphics Principles and Practice Hughes et al 10 www.cgpp.net).

Although it refers to modeling in the abstractive sense, It can still be applied to geometrical modeling.

Breaking it down to relevant terms, it could mean the following:

I - The model form, details and qualities ("understand the phenomenon you’re modeling"):

Careful study of reference and planning is key, gather all the reference you can, look at any similar models you can find. The more time you spend in preparing and studying the reference, the easier and less time it will take to model it.

II - What are you going to use this 3D model for ("your goal in modeling it"): 

A high resolution still render? or a real-time engine? maximum poly-count? do you need to animate it? what are the technical limitations? how close is the camera going to be looking at it? Considering all of these questions before starting any modeling process helps greatly.

III - Choose your modeling method and targeted result ("rich-enough abstraction") :

Know what tool are you going to use, and how accurate or detailed you will make it. Plan ahead what parts are you going to model, and decide in the beginning if you are going to use textures for certain details.

IV - How are you going to render it and on what platforms ( "adequate representations"):

This point can be combined with your goal in modeling, but if you have full control over the project it could mean how are you going to render your model, and represent it under the best of light.

V - Continuous tests ("verify that your abstraction was appropriate"):

Always check the work you do, this is especially obvious in games. Testing will always help you to concentrate your effort on the parts that matter the most, and avoid any needless detailing work for areas not seen by the camera or are in shadows. you will find it particularly important to get the proportions right. You will probably feel as I do, that this needs a complete section to cover, when you know mis-calculated proportions are the number one issue facing 3D modelers I have worked with.

Principle Summary

Not to over-complicate principles and procedures; simply put. Just use good old common sense to study the situation, plan your work before starting, then go ahead and model checking and testing that everything is alright along the way.

The very best advice I got from a fellow artist; Ted Chaplin, who is an amazingly experienced 3D modeler/illustrator/art director/TD/supervisor and one of the best people I have ever worked with, was the good old "longest way round is the shortest way home".

If you try to skip on reference gathering, or knowing the requirements of the model, and just go ahead bashing on it with brute force until it's completed; you will probably pay dearly, with revisions and corrections that will take far longer to modify, than doing it right from the start.

Another great advice I got from a colleague of mine, Adrian Besleaga when I was starting out in 3D and kept asking him, whether or not my model was going in the right direction was this: stop bugging me, you have a reference. Keep comparing your model with the reference. That's all. This taken to heart will really help anyone be a better professional :) .

 

You have an immense brain power! you have the ability (if you put your mind to it), to tap your potential and and achieve amazing feats, you can read up to thousands of words in a minute, or come up with the next leap in science. If at the moment you are only able to trace blueprints to create 3D models and find it very difficult to model something from image reference or imagination; keep trying and I assure you, you will achieve great results!

Finally, It's a bit embarrasing to show on the web. But, whenever I meet up with someone who wants to learn 3D modeling or to be a 3D artist, I always show them my very first works and the progress I made.

Ali Ismail Modeling Progress

I can't even find my very first models, but you get the idea. Now, you are very lucky that you have an abundance of learning material. With a bit of persistence, you can greatly fast forward you progress.

As always, any feedback or corrections you provide regarding this article will be highly appreciated.