Mesh File (STL / OBJ / DAE / glTF)

A 3D file that describes an object's shape as a collection of triangles — the visual “shell” of a robot model.

A mesh file breaks a part or object's surface into many triangles and records their vertex coordinates and faces. Common formats include: STL, which stores geometry only, with no color or defined units; OBJ, which stores geometry plus texture coordinates, with materials in a companion .mtl file; DAE (COLLADA), an XML format that can carry materials and color and is common in ROS; and glTF, a newer format from the Khronos Group that supports physically based materials and suits web and rendering use cases. Robot description files like URDF and MJCF don't store shape directly — they reference these mesh files separately for the visual appearance and for the collision geometry used in physics checks. Collision meshes usually need to be simplified or convex-decomposed, or simulation becomes slow and unstable; another common pitfall is mixing up whether an STL file's units are millimeters or meters, which can make a model a thousand times too big.

ExampleIn a URDF exported from SolidWorks, each link references a meshes/xxx.STL file for both its visual appearance and its collision shape.

Also called

STL, OBJ, DAE, glTF, model file

Related

Unified Robot Description Format · MJCF (MuJoCo XML Format) · Collision Geometry (Collider) · Convex Decomposition · Triangle Mesh · SolidWorks to URDF Exporter

Sources

Khronos glTF
ROS Wiki: URDF link（mesh 引用） (Chinese)