What is a polygon in 3D modeling?

What is a polygon in 3D modeling?

Polygons are 2D shapes that are used to create 3D meshes. Did you ever make those paper cutouts that turned into shapes like pyramids or cubes in school when learning about 3D shapes? Well, in polygonal modeling, a mesh is just like that.

Polygons are fundamental to 3D modeling.

Every polygon is formed by at least three vertices and edges coming together to create a closed shape. Three vertices, or points, makes a triangle—tri for short. Four of them makes a quad. It’s industry standard to only use tris and quads in a mesh as much as possible. There is a term for polygons that have more edges than quads: they’re called N-Gons, and really should be avoided because they are more likely to cause artifacts in your textures and materials.

Pieces of a Polygon.

Understanding what constitutes a polygon will help you better manipulate and edit them while modeling. Let’s look more closely at the pieces of a polygon and where they fit in a 3D model’s mesh.

Vertex

A vertex is the point where two edges meet and join. If you move the position of a vertex, you will also affect the position of the two edges simultaneously.

Edge

An edge appears in modeling programs as a line. An edge has two vertices, one on each end. When at least three edges join at their vertices, a polygon is formed: specifically, a triangle.

Face

A face is the flat 2D shape created when a polygon is formed. Many polygonal modeling software will allow you to select a face specifically and change its position editing your mesh. Moving a face would of course, simultaneously move the edges and vertices that form it.

Create any shape imaginable using polygons.

To illustrate a simple example of polygons and complete 3D models, consider the construction of a basic cube. A cube has six faces, 12 edges, and 8 vertices linked together to create one object. With these basic principles, CG artists can use polygons to create any shape they’d like.

If you look at the mesh, or wireframe of any 3D object, you will see the many polygons wove together to create that shape, from a human face to something born wholly from their imagination.

The difference between high-poly, low-poly, and retopology.

When it comes to polygonal modeling, there are a few key industry terms you should be aware of.

High-Poly

A high-poly model refers to a mesh that was created with extreme detail, and usually no regard for the final poly count. Often, high poly models aren’t designed with polygons at all. Typically, they are sculpted using voxel-based 3D methods.

Think of a single voxel like a pixel in 2D art. Each pixel stores color information. A voxel is no different. It’s a single point that stores relevant 3D information, and each has a place in a three-dimensional grid.

Using these methods allows artists to sculpt 3D objects in real-time. When complete, they can export the 3D model as a mesh, in which case, computer algorithms take care of the polygonal modeling. The results are often impressive, but bloated when polygons are concerned. Hence the name, high poly.

Low-Poly

In many industries, having 3D models with low numbers of polygons is desired. Often the term low-poly is used to describe a model that not only has a small number of polygons, but has a mesh that has been recreated or optimized to lower its poly count.

Retopology

This brings us to retopology: the process of turning a high-poly model into a low-poly one. There are several methods, and various software may even have specific tools available to aid the retopology process. For many artists, this is a necessary step in their workflow.

Most commonly, artists will simplify the topology, but bake the more complex, high-poly version onto the objects surface textures. This way very little detail is lost, despite greatly optimizing a model’s performance.

Hyper-realistic 3D rendering of bird using 3D polygon modeling

Simple polygonal modeling techniques you can use.

Here are basic techniques artists can use when creating polygons for 3D modeling.

Extrusion

Extrusion is a basic modeling tool that enables artists to select a piece of a mesh, usually a face or an edge, and extrude it inwards or outwards. This causes an extension of the original shape or can literally tunnel into the shape.

Subdivision

Subdivision is a useful tool and technique for creating smooth 3D models out of polygons. Take our earlier example of a simple cube that only has six faces. One could subdivide each face of the cube, dividing it into smaller quadrants. For example, an artist could subdivide the cube once vertically, and once horizontally, thus splitting each face into four smaller faces.

Subdivision is a great way to increase poly count while letting a basic shape become the starting point for modeling. In general, subdivision can be completed in two types.

Uniform subdivision. This is when the entire object is subdivided evenly. This will impact the entire mesh.

Selective subdivision. In this method of subdividing, the artist only selects a single quadrant, for example one face, and imposes the desired number of subdivisions. The remainder of the mesh is unaffected.

Bevels

On their own, the edges of a model are perfectly sharp. Consider again the cube example, where two faces share an edge. You could manipulate the angle between two faces making it square, obtuse, or acute, but the edge itself would remain sharp.

Beveling tools allow artists to select an edge and then add any number of bevels to soften an edge. This is a useful tool but should be used carefully as it can easily add unwanted polygons or cause conflicts with topology if too much detail is added to one bevel.

Use Adobe Substance 3D to create inspiring art without fussing over polygons.

For many 3D workflows, polygonal modeling may seem unavoidable. Managing topology can feel like a hassle, especially in situations when having a perfectly streamlined mesh may not be required. This is especially the case in product-focused industries that want to take advantage of 3D.

In these situations, having a software that not only allows you to block out shapes quickly and efficiently, but can also produce high-quality results for both hard surface and organic surface modeling, can make all the difference in your success in 3D.

Adobe Substance 3D Modeler is a voxel-based sculpting software that aims to make 3D modeling feel as gestural and natural as working with real clay. From start to finish, artists don’t need to worry about polygons, topology, or UV mapping. All these steps are handled by the software at export, and the artist has export options available to help guide this process.

To learn more about the fundamentals of 3D animation, check out our comprehensive guide on 3D animation for an in-depth look at its techniques and applications.

Conclusion

Mastering polygons, vertices, and edges is key to excelling in 3D modeling. With this knowledge, you can create clean, efficient, and visually stunning models, whether you’re a beginner or a seasoned professional.

FAQs

Q1: What are polygons in simple terms?
Polygons are the flat shapes that make up the surface of 3D objects.

Q2: Why are vertices important in 3D modeling?
Vertices define the shape and form of 3D objects by acting as connection points for edges.

Q3: What tools can I use to edit edges?
Popular tools include edge loops and bevel tools in software like Blender and Maya.

Q4: What is bad topology, and how can it be fixed?
Bad topology occurs when polygons and edges are poorly arranged. Retopology can fix this issue.

Q5: How do polygons affect rendering performance?
More polygons mean higher detail but can reduce rendering speed.

Q6: Can a 3D model exist without vertices?
No, vertices are essential as they are the foundation of all 3D geometry.

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