Beyond the visual, the world of 3D has a language all its own. Below you can find a variety of terms that may be helpful when learning or improving your 3D knowledge:
Ambient Occlusion - (often shortened to AO) Creates the appearance of dark crevices and corners in a mesh by occluding ambient light. Can be used in a texture format, or created dynamically. Sketchfab supports Screen Space Ambient Occlusion (SSAO) as a dynamic method but also supports the use of textures.
API - stands for Application Program Interface, a set of functions and procedures allowing the creation of applications that access the features or data of an operating system, application, or other service.
Baking - the process of calculating light and shadow information into the 3D geometry or texture of your model. Baking is done in your 3D software of choice before uploading to Sketchfab. You can bake a variety of effects into your models, such as lighting, textures, or animation. Once an effect is baked into the model, it cannot be dynamically updated. However, it can be updated if baked into the texture.
Bones - together comprise a skeleton (or "armature") that is used to manipulate a mesh. Bones are typically controlled during the animation process by a rig. You can view Bones and Bone Weights in animated, rigged models on Sketchfab using the Model Inspector. The keyboard shortcut is 6.
Bump map - a technique that uses texture added to the surface of a 3D model to create the illusion of depth (or relief) by changing the way the renderer and lights “see” the model
Decimation - a function that can reduce the number of polygons determining a 3D model's mesh. Decimation can radically reduce a model's processing needs, but may not create ideal model topology.
Displacement map - a technique that uses textures to physically displace the vertices' position on a 3D model, producing a greater sense of depth and detail.
Edge - a line that exists between two vertices
Face - the most basic part of a 3D polygon, when three or more vertices (points) connect to make a visible surface. You can see the faces and edges of the cube in the Sketchfab viewer below.
Geometry - an extension of 2-D geometry, taking the third dimension into account. Most 3D models are made up of quads or triangles.
MatCap ("material capture") - a quick and easy way to apply material and light reflection information to the whole model, to check its shape and normals. Adding a MatCap shader displays a color for every vertex normal direction relative to the camera on your 3D model. (See: Materials (MatCap))
Material - refers to the optical properties of a 3D object's surface, such as color, shininess, etc. You can use multiple materials on a single 3D model to, for example, add visual properties to different parts of a gaming character.
Mesh - a collection of vertices, edges and faces that define the shape of a 3D model
Normal - the direction a vertex in a 3D model points towards. Vertex normals help in the computation of how much light a surface gets (by measuring the angle between the normal and the light direction). You can explore the Vertex Normals for a Sketchfab model under the Geometry tab of the Model Inspector.
Normal map - a technique used to add surface detail to a 3D model by bending the normals, without adding more polygons (and therefore processing needs). A normal map uses RGB values to fake the lighting of bumps and dents on the surface, and create the illusion of a high-resolution model. Currently, Sketchfab only supports tangent space normal mapping.
Physically Based Rendering (PBR) - a methodology, not necessarily a hard standard. It is a method of shading and rendering 3D models that provides a more accurate representation of how light interacts with surfaces from a physically accurate standpoint. See: PBR
Point cloud - a set of data points in 3D space, generally produced by 3D scanners, which measure a large number of points on the external surfaces of objects around them. (See: Point Clouds)
Polygon - a shape with three or more vertices connected
Poly count - the number of polygons in a 3D model's mesh
Render - the process of producing an image based on 3D data stored within a computer
Rig - the process of adding controls to your 3D model in order to make animating easier. Without a rig, animating would be extremely difficult.
Shader/shading - a function that determines how the appearance of a 3D model's material(s) varies with the angle of the light
Texture - an image mapped to the surface of your model's material(s)
Topology - the way the polygons (whether 3, 4, or 5+ sided) of a 3D model's mesh are organized and connected to one another. You can see this for a Sketchfab model in the Model Inspector's Wireframe view, or through the keyboard shortcut - 5.
UV mapping- the process of wrapping a 2D texture to a 3D model's surface. (U and V are used because X/Y/Z are often used to denote the axes of the 3D object in space.)
UV unwrapping - the process of flattening out the polygons of your model, and converting them into a single 2D square.
Vertex - the smallest part of a 3D model, the point of intersection between three or more edges (lines) in 3D space