Format Guide

OFF File Format (.off)

The minimal ASCII mesh format — clean, dependency-free polygon geometry for research and processing tools.

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Extension.off
Full nameObject File Format
Geometry typePolygon mesh (triangles and polygons)
VariantsOFF (plain), COFF (color), NOFF (normals), CNOFF (color+normals)
Open standardYes
Supports colorCOFF variant only
Supports normalsNOFF variant only
EncodingASCII text

What is an OFF file?

OFF (Object File Format) is a minimal ASCII text format for representing polygon meshes. An OFF file starts with the keyword 'OFF', followed by counts of vertices, faces, and edges, then vertex coordinates, and finally faces (each defined by a vertex count and indices). Optional color variants (COFF for color, NOFF for normals) add per-vertex attributes. OFF was popularized by the Princeton Shape Benchmark and Geomview visualization software, becoming a de facto standard for distributing polygon mesh test datasets in computational geometry research. It is intentionally simple — no materials, no textures, no hierarchy — just raw polygon geometry.

Common Uses of OFF Files

Computational Geometry Research

Academic geometry processing libraries (CGAL, libigl, OpenMesh) use OFF as a common test format. Princeton Shape Benchmark and similar datasets are distributed as OFF files.

Geometry Processing Pipelines

OFF is used in mesh processing pipelines where a simple, dependency-free, human-readable format is preferred between preprocessing scripts and mesh analysis tools.

Geomview Visualization

Geomview, the interactive 3D viewer from the Geometry Center, uses OFF as its native format and drove adoption in the academic visualization community.

Software Support

MeshLab, Geomview, CGAL, libigl, OpenMesh, Blender (via import plugin), and 3D CAD Converter.

Convert This Format

Commonly converted to STL for 3D printing, to OBJ for rendering, or to PLY for datasets requiring per-vertex attributes. Mesh repair is often needed before printing OFF files.