In this first part, learn how to create clean 3D models by following these simple tips and practical examples.
Welcome to this 3D modeling series where I’m going to give you some advice about creating robust 3D models. This advice is based on industry-wide best practices that will allow your models to open, render, and perform their best, no matter what sort of project is their final destination.
Many of you may already know how to use 3D software to build objects with specific tools. That’s why the focus of the series isn’t meant to be a getting started guide to 3D modeling.
That said, I’ll take you through situations where you have to solve common problems with your modeling and show you how to best find a solution based on proper modeling techniques.
Furthermore, I’ll be using Maya, but the techniques aren’t tied to any specific 3D software, apart from a bonus lesson where I’ll be introducing some quick tools in Autodesk Maya. Therefore, you can follow this article with your preferred tool!
In this first part, let’s talk about a few generic terms and practices you absolutely have to know before getting into 3D modeling.
Starting on the Right Foot: 3D Modeling Blockout
The presence of simple geometries that define the masses, spaces, and proportions can give you a quick idea of what you’re going to achieve when modeling.
In this phase, you shouldn’t care too much about the quality. Instead, plan your 3D model (think of this like a rough sketch). This is called the “blockout” phase, as you’re creating blocks that help you visualize the end product.
Despite being extremely important, many 3D artists skip this step. Don’t be that person.
Planning a building with simple primitive shapes. Image via World of Level Design.
Proportions are also important if you plan to build a world made of different assets with the right scaling.
3D modeling blockoutcan also be useful if you want to make some quick changes while designing your asset. You can test if a component suits you better in a certain position. If not, you can briskly move it away.
Again, the blockout serves as base for your 3D model. In fact, you can continue from your simple shapes and add more details as you work.
The same approach is used in digital sculpting when you start from big masses by adding secondary, tertiary, and micro details.
Bit of Basic Terminology
Let’s see the first terms in action!
Structure edges define the shape of your 3D model in terms of topology. In fact, if we delete these edges, we come out with a completely different object.
In the 3D modeling blockout, for instance, these edges are extremely important because they draw the silhouette of your 3D model.
The following example shows structure edges.
Structure edges for a simple shape.
We also have support edges, which help preserve the sharpness when you subdivide your 3D model.
Let’s take the previous example and apply more edges. If we subdivide the model, we’re unable to maintain the original shape as the corners would be smoothed. That’s not what we want. Here’s where the support edges come in handy!
Note: In a few examples, I’ll be using the smooth mesh preview feature (that’s inside of Maya—number 3 as shortcut), instead of a real mesh subdivision. That feature keeps the same number of edges but smoothes the geometry—that’s easier for you to visualize the original edge flow, which is kept after smoothing.
Always remember to apply a real subdivision, If you plan to export for external 3D software.
In the following image, the mesh is being smoothed, but the original edges don’t change in order to have a cleaner representation for you.
See the difference!
Let’s associate two support edges per hard edge to keep the sharpness. The inner edges spread all around the 3D model.
It’s fine in this case, because the model doesn’t have other details. But, we’ll learn how to redirect some edges later in the series.
The support edges are indicated by blue lines. When we smooth the model, the sharpness is now retained.
The support edges are indicated by blue lines.
Another technique that keeps the sharpness while avoiding many support edges is called Creasing.
There are some benefits when you decide to work with a Crease tool.
Your topology looks nice and clean, as we don’t need to add any extra support edges.Most 3D software has the Crease tool integrated, which makes this a practical tool to use.
Nonetheless, this technique can also have drawbacks.
When you export the model to an open file format for other 3D applications, you can lose the effect.
It’s better to limit the effect inside of your production environment.
As we know, without support edges, we cannot maintain the shape when we smooth the object.
Smooth preview—we lose the sharpness.
However, if we select some edges (as in the following figure), and apply a Crease tool, we hold some sharpness without any additional support edges.
Selecting edges to crease (blue).
Smooth preview with creasing.
Real Subdivision with smooth preview.
Topology and Edge Flow
The industry standard requires that your model has a good topology, which is related to how your edges are distributed on your 3D object.
A good edge flow is important for a number of reasons:
It’s perfect to show in your portfolio.It helps you understand the different areas a model is made of.It’s useful to speed up the modeling or add details, because the faces and edges can be easily selected.It allows adding new edge loops with ease.It avoids deformations and other unwanted results.
Consider the following example, which may appear to be fine, but displays a few problems we want to correct.
Near the hole, we have an edge flow that creates some poles (in this case, vertices with five incoming edges) close to the circumference (the red circles).
We’ll talk about poles in a future part of the series but, for now, remember that poles must be located away from a curved surface. Otherwise, we’ll see a bit of distortion or some pincheffects near the circumference.
Furthermore, it’s better to have one more support edge around the hole to have a sharper and more realistic hard surface.
Let’s change the topology and the edge flow a bit!
A good topology.
Edge flow around the hole.
We’ve just mitigated the problem connected with poles. They’ve moved away from the hole—which is good—and we added an edge loop to reinforce the rounded structure.
We also created other edge loops around the hole, which allows you to quickly model some extrusion and add more details with ease.
Edge Distribution and Spacing
When you plan your 3D model from the beginning, a good practice is to start with a low-poly model. That way, you’ll be able to place your edges and control your distribution in a precise way.
As a rule of the thumb, it’s better to have an even spacing of your edges. This mainly applies to surfaces showing curvatures, or critical areas where subdivision might cause artifacts.
Let’s see an example.
This is a prototype that might represent a futuristic weapon (use your imagination). We’re interested in the external shield and its edge distribution.
Futuristic weapon prototype example.
If we have a quick look at the shape, we have an interesting curvature. Imagine that we want to turn the smooth corners into sharp ones.
By smoothing the geometry, the transition becomes soft. How can we keep the sharpness?
Notice the interesting curvature.
When Support Edges Don’t Work
We learned that support edges can help but, in this case, we’ll run into a problem. When the surface is curvedyou absolutely need to distribute the edge uniformly, otherwise you’ll introduce some unwanted effects.
Let’s try to add support edges and smooth the geometry out. The result is being translated into a bad shading. Despite having hard corners now, we introduced a few errors in the curvature.
Why is that?
Well, you’re telling the software to keep the hard edges also on the curvature, which isn’t what we want! We can solve the problem by creating a uniform distribution in the curvature and close to the borders.
You can solve this by creating a uniform distribution in the curvature.
Keeping the Edge Distribution
We want to create an even spacing and avoid shading problems. Furthermore, close to the borders, we adjusted the edge flow to introduce some sharpness.
Examples of correct and incorrect distribution.
The difference is evident. We’re not facing bad shading anymore—we have hard edges now!
Comparing the smooth profile with the sharp one
Quads vs. Tris?
When you approach 3D modeling, you probably ask yourself whether it’s better to use triangles or quadrilaterals.
Well, this depends on your goals. But, a good practice is to get used to four sided polygons because of their benefits.
Actually, most of the time artists work with quadrilaterals for a series of reasons:
They are easier to manage.Mesh subdivision works great.Quadrilaterals give you a clear understanding of how you can modify components and parts of an object.Artists can create edge loops or select a ring of faces in specific areas (also useful in organic modeling).They speed up the modeling process.They avoid distortions or artifacts when animating or deforming a 3D mesh.
. . . and many other advantages!
Personally, I’ve mostly modeled with quads and I strongly recommend to do that.
When Are Tris an Option for 3D modeling?
Poly count is important for the game industry and tris help a bit in the geometry optimization. Working with triangles helps you further reduce the number of components.
Many static 3D assets, for instance, are sometimes modeled with tris. However, nowadays, technologies have become stronger and, in a foreseeable future, we won’t probably face any issues with poly count at all.
Just to mention, Unreal Engine 5 has already introduced its own algorithm (Nanite) to treat dense meshes in real-time.
What About Quads Mixed with Tris?
Sometimes, the presence of tris in the topology is still acceptable, provided that you don’t exaggerate and you keep only a few of them.
This is my advice:
Hide tris from your camera by positioning them in occluded parts, for instance.If they’re not possible to hide, position them over flat surfaces in order to avoid strange effects on the shading when the geometry is subdivided.
In the following images, we put some random edges to form tris. On a flat surface, once subdivided, the shading looks fine. However, on a curved surface we notice a few artifacts.
So, bear in mind where you distribute your triangles!
Be mindful of where you distribute your triangles.
What About N-Gons?
No way! They’re bad because they cause several problems with the mesh subdivision, and 3D engines might misinterpret the topology. Avoid them!
We talked about edge redirection when we explained the topology and the edge flow. Why is it important? Basically, edge redirection comes in handy when you want to modify the topology for a specific reason.
You might want to create edge loops around a particular area of your model because you need more details, or you want to build specific structures.
Let’s take this example to explain what I mean. Imagine that we have a simple object and want to have the possibility to add edge loops around a few selected faces with ease.
With this initial topology, that’s not possible. We need to redirect some edges.
A simple geometry.
We want to add edges around the selected faces.
We add four diagonal edges and delete the edges selected in blue.
Unfortunately, we come out with n-gons, which isn’t good. So, we have to add new edges to reconnect some vertices.
You see that the edge flow has changed, and we’re able to add as many edge loops as we want now!
We have a ring.
We can add several edge loops now.
From there, you can add more shapes with extrusion and produce a blockout with a few elements.
For instance . . .
Extruding some shapes.
Finally, edge redirection can be planned in advance, but you might also need to change the edge flow in the middle of your project, where there might be other parts and details to be added.
It’s an important step of your work!
Where Shading Can Help
Believe it or not, shaders are our friends while 3D modeling. What do I mean by that?
Artifacts can be detected better if we use a material with specular reflections. You don’t have to be super-picky, but a simple Phong or Blinn does the trick!
If we just use a matte material like Lambert, we might miss some bad shading.
Let’s consider the following example:
Let’s try to modify the topology on the surface a bit. There’s no reason to add the following edge loops (as you can see), but I did that on purpose in order to show how a Blinn shader can help to detect unwanted reflections.
Despite having all quads, the edge distribution, in this case, generates an outline that we don’t want.
If we had used a simple Lambert shader, we wouldn’t have been able to see the problem, but that’s not a solution.
My advice is to use a shader with specular reflections when modeling a 3D object. The previous is an example of bad shading, which I intentionally introduced. Just remember that many other situations in 3D modeling can lead to bad shading.
Modeling with a proper shader is also fantastic for another reason—we can evaluate the quality and direction of our specular reflections.
Specular reflections tend to follow the edge flow around a surface, because of the way faces and normals are oriented during the modeling.
We cannot say that a reflection is right and another is not. Modeling can just affect the shape of the specular reflection.
In this last example, the reflection doesn’t turn around the corner like in the previous situations. This is due to the different edge flow and edge distribution.
If You Want to Rig and Animate, Plan Your Modeling in Advance
As a last example in this first part of the series, I’d like to mention the importance of a good edge flow, distribution, and edge loops in a character that will be rigged.
A character I created for another project. Image via Artstation.
As a good practice while modeling your character is to think about the parts that will be deformed. You’ll act by adding more geometry and edges in particular areas.
If you observe the leg close to the knee, you’ll notice more edgedensity, because that part can be bent.
In these areas (knee, elbow, knuckles, etc.), you should make the anatomy clear. The image on the right (below), the knee position is awkward and we cannot exactly understand where it is.
Furthermore, we would encounter a few problems in the rigging process because the bending isn’t good.
The correct way.
The incorrect way.
Having edge loops around the leg area is good for deformation. A bad topology would create artifacts and bad shading during the animation.
Edge loops connecting the leg and body.
The previous character has a simple geometry for the head, thus it’s not fundamental to create specific edge loops for muscle deformation.
However, if you want to represent muscles in a head, a good practice is to add edge loops in strategic areas.
They roughly follow the flow of the muscles and help control specific parts.
They’re also helpful while animating as they provide accuracy in the deformation of specific anatomical components.
Head topology with edge loops. Image via lesterbanks.com.
In Part 1, we became familiar with a bit of terminology in connection with 3D modeling. We also explored good modeling practices that you should take into account before starting your next project.
In the next episode, we’ll be describing other cool arguments and practices. In the meantime, you can browse through my Artstation to discover more projects.
The post Part 1: The Basics of Building a Clean 3D Model appeared first on The Shutterstock Blog.
Did you miss our previous article…