A glossary of 3D generation terms.
The terms of 3D generation and 3D production, as we use them in our notes. Each one comes with a short definition and, where it helps, a link to the note that goes further.
- Base color
- The color of a surface before light and shadow are applied. It is the first map of a PBR material, also called albedo.
- Blocking
- The first modelling pass, with simple volumes that set proportions and scale before any detail.
- B-rep
- Boundary representation: the CAD description of a solid by its exact surfaces, edges and vertices.
- CAD
- Computer-aided design. Parametric, exact geometry made for engineering and manufacturing.
- Chamfer distance
- The mean distance from each sampled point of one shape to the nearest point of another, in both directions. Lower is better. See evaluation.
- Edge loop
- A ring of connected edges around a mesh, used to add detail and to control how a surface bends.
- Editable 3D
- A 3D object an artist can keep working on: separate parts, real-world scale, pivots and hierarchy. See editable 3D generation.
- F-score
- The harmonic mean of precision and recall at a distance threshold, from 0 to 1. Higher is better.
- FBX
- Autodesk's exchange format for meshes, hierarchies, materials and animation, common in game and film pipelines.
- Foundation model
- A large model trained on broad data and adapted to many tasks. See 3D foundation models.
- Gaussian splatting
- A representation that renders a scene from many small 3D Gaussians, each with a color and an opacity. It was introduced for real-time rendering in 2023.
- glTF and GLB
- The Khronos open standard for 3D scenes. GLB is its single binary file, and its distances are in metres.
- Held-out object
- An object kept out of training and used to measure a model.
- Hierarchy
- The parent and child relations between objects in a scene. Moving a parent moves its children.
- Instance
- A copy of an object that shares its mesh data, such as the four legs of a table.
- IoU
- Intersection over union: the volume two shapes share divided by the volume either one covers.
- LOD
- Level of detail. Lighter versions of a mesh, shown when the object is far from the camera.
- Manifold
- A mesh where every edge borders exactly two faces. Booleans, simulation and 3D printing expect manifold meshes.
- Material
- The set of properties that describes how a surface reflects light: base color, roughness, metallic, normal map.
- Mesh
- A surface described by vertices, edges and faces. It is the main representation of games, film and product visualisation.
- Modifier
- In Blender, an operation applied to an object that stays editable, such as a bevel, a mirror or a subdivision.
- NeRF
- Neural radiance field: a network that maps a 3D position and a view direction to color and density, trained from photographs (2020).
- Normal
- The direction a surface faces at a point.
- Normal map
- A texture that stores normals to add fine surface detail to a lighter mesh.
- OBJ
- A plain text mesh format with groups and material files, used to exchange a single mesh.
- Part
- One component of an object that can be selected, moved and textured on its own.
- Part-based generation
- Generation that builds each component of an object as its own object from the start.
- Part segmentation
- Splitting a finished mesh into regions that correspond to its parts.
- PBR
- Physically based rendering: shading built on measured physical quantities, so a material holds up across lighting conditions and engines.
- Pivot
- The point an object rotates and scales around. In Blender it is called the origin.
- Point cloud
- A set of points sampled on a surface, the raw output of lidar and photogrammetry.
- Polygon
- A face of a mesh. Triangles have three sides and quads four. Artists model in quads, engines render triangles.
- Procedural modelling
- Building geometry with rules, nodes or code, so changing a parameter rebuilds the object.
- Real-world scale
- Dimensions in metres or centimetres that match the real object, so it fits the scene it is placed in.
- Retopology
- Rebuilding a mesh with a clean, lighter layout of polygons over a detailed one.
- Rigging
- Adding a skeleton or controls so an object or a character can be animated.
- Signed distance field
- A function that gives, for any point in space, its distance to the surface, negative inside the object.
- Subdivision surface
- A method that splits each face into smaller ones and rounds the shape, used to model smooth surfaces.
- Topology
- The layout of the vertices, edges and faces of a mesh.
- Transform
- The position, rotation and scale of an object.
- USD
- Universal Scene Description, the scene format Pixar released as open source in 2016, built for large scenes assembled in layers.
- UV map
- The flattening of a 3D surface onto a 2D square, so an image can be painted on it.
- Voxel
- One cell of a regular 3D grid.
- Watertight
- A closed surface that encloses a volume.
Sandflow is a frontier lab building foundation models for 3D. Our first model is on its way.