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Python library for loading and using triangular meshes.

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Trimesh is a pure Python (2.7-3.4+) library for loading and using triangular meshes with an emphasis on watertight surfaces. The goal of the library is to provide a full featured and well tested Trimesh object which allows for easy manipulation and analysis, in the style of the Polygon object in the Shapely library.

The API is mostly stable, but this should not be relied on and is not guaranteed: install a specific version if you plan on deploying something using trimesh.

Pull requests are appreciated and responded to promptly! If you'd like to contribute, here is an up to date list of potential enhancements although things not on that list are also welcome. Here are some tips for writing mesh code in Python.

Basic Installation


easy to install is a core goal, thus the only hard dependency is numpy. Installing other packages adds functionality but is not required. For the easiest install with just numpy,
can generally install
cleanly on Windows, Linux, and OSX:
pip install trimesh

More functionality is available when soft dependencies are installed. This includes things like convex hulls (

), graph operations (
), faster ray queries (
), vector path handling (
), preview windows (
), faster cache checks (
), etc. To install
with the soft dependencies that generally install cleanly on Linux, OSX, and Windows using
pip install trimesh[easy]

Further information is available in the advanced installation documentation.

Quick Start

Here is an example of loading a mesh from file and colorizing its faces. Here is a nicely formatted ipython notebook version of this example. Also check out the cross section example or possibly the integration of a function over a mesh example.

import numpy as np
import trimesh

attach to logger so trimesh messages will be printed to console


mesh objects can be created from existing faces and vertex data

mesh = trimesh.Trimesh(vertices=[[0, 0, 0], [0, 0, 1], [0, 1, 0]], faces=[[0, 1, 2]])

by default, Trimesh will do a light processing, which will

remove any NaN values and merge vertices that share position

if you want to not do this on load, you can pass process=False

mesh = trimesh.Trimesh(vertices=[[0, 0, 0], [0, 0, 1], [0, 1, 0]], faces=[[0, 1, 2]], process=False)

some formats represent multiple meshes with multiple instances

the loader tries to return the datatype which makes the most sense

which will for scene-like files will return a trimesh.Scene object.

if you always want a straight trimesh.Trimesh you can ask the

loader to "force" the result into a mesh through concatenation

mesh = trimesh.load('models/CesiumMilkTruck.glb', force='mesh')

mesh objects can be loaded from a file name or from a buffer

you can pass any of the kwargs for the Trimesh constructor

to trimesh.load, including process=False if you would like

to preserve the original loaded data without merging vertices

STL files will be a soup of disconnected triangles without

merging vertices however and will not register as watertight

mesh = trimesh.load('../models/featuretype.STL')

is the current mesh watertight?


what's the euler number for the mesh?


the convex hull is another Trimesh object that is available as a property

lets compare the volume of our mesh with the volume of its convex hull

print(mesh.volume / mesh.convex_hull.volume)

since the mesh is watertight, it means there is a

volumetric center of mass which we can set as the origin for our mesh

mesh.vertices -= mesh.center_mass

what's the moment of inertia for the mesh?


if there are multiple bodies in the mesh we can split the mesh by

connected components of face adjacency

since this example mesh is a single watertight body we get a list of one mesh


facets are groups of coplanar adjacent faces

set each facet to a random color

colors are 8 bit RGBA by default (n, 4) np.uint8

for facet in mesh.facets: mesh.visual.face_colors[facet] = trimesh.visual.random_color()

preview mesh in an opengl window if you installed pyglet with pip

transform method can be passed a (4, 4) matrix and will cleanly apply the transform


axis aligned bounding box is available


a minimum volume oriented bounding box also available

primitives are subclasses of Trimesh objects which automatically generate

faces and vertices from data stored in the 'primitive' attribute

mesh.bounding_box_oriented.primitive.extents mesh.bounding_box_oriented.primitive.transform

show the mesh appended with its oriented bounding box

the bounding box is a trimesh.primitives.Box object, which subclasses

Trimesh and lazily evaluates to fill in vertices and faces when requested

(press w in viewer to see triangles)

(mesh + mesh.bounding_box_oriented).show()

bounding spheres and bounding cylinders of meshes are also

available, and will be the minimum volume version of each

except in certain degenerate cases, where they will be no worse

than a least squares fit version of the primitive.

print(mesh.bounding_box_oriented.volume, mesh.bounding_cylinder.volume, mesh.bounding_sphere.volume)


  • Import meshes from binary/ASCII STL, Wavefront OBJ, ASCII OFF, binary/ASCII PLY, GLTF/GLB 2.0, 3MF, XAML, 3DXML, etc.
  • Import and export 2D or 3D vector paths from/to DXF or SVG files
  • Import geometry files using the GMSH SDK if installed (BREP, STEP, IGES, INP, BDF, etc)
  • Export meshes as binary STL, binary PLY, ASCII OFF, OBJ, GLTF/GLB 2.0, COLLADA, etc.
  • Export meshes using the GMSH SDK if installed (Abaqus INP, Nastran BDF, etc)
  • Preview meshes using pyglet or in- line in jupyter notebooks using three.js
  • Automatic hashing of numpy arrays for change tracking using MD5, zlib CRC, or xxhash
  • Internal caching of computed values validated from hashes
  • Calculate face adjacencies, face angles, vertex defects, etc.
  • Calculate cross sections, i.e. the slicing operation used in 3D printing
  • Slice meshes with one or multiple arbitrary planes and return the resulting surface
  • Split mesh based on face connectivity using networkx, graph-tool, or scipy.sparse
  • Calculate mass properties, including volume, center of mass, moment of inertia, principal components of inertia vectors and components
  • Repair simple problems with triangle winding, normals, and quad/tri holes
  • Convex hulls of meshes
  • Compute rotation/translation/tessellation invariant identifier and find duplicate meshes
  • Determine if a mesh is watertight, convex, etc.
  • Uniformly sample the surface of a mesh
  • Ray-mesh queries including location, triangle index, etc.
  • Boolean operations on meshes (intersection, union, difference) using OpenSCAD or Blender as a back end. Note that mesh booleans in general are usually slow and unreliable
  • Voxelize watertight meshes
  • Volume mesh generation (TETgen) using Gmsh SDK
  • Smooth watertight meshes using laplacian smoothing algorithms (Classic, Taubin, Humphrey)
  • Subdivide faces of a mesh
  • Minimum volume oriented bounding boxes for meshes
  • Minimum volume bounding spheres
  • Symbolic integration of functions over triangles
  • Calculate nearest point on mesh surface and signed distance
  • Determine if a point lies inside or outside of a well constructed mesh using signed distance
  • Primitive objects (Box, Cylinder, Sphere, Extrusion) which are subclassed Trimesh objects and have all the same features (inertia, viewers, etc)
  • Simple scene graph and transform tree which can be rendered (pyglet window, three.js in a jupyter notebook, pyrender) or exported.
  • Many utility functions, like transforming points, unitizing vectors, aligning vectors, tracking numpy arrays for changes, grouping rows, etc.


Trimesh includes an optional

based viewer for debugging and inspecting. In the mesh view window, opened with
, the following commands can be used:
  • mouse click + drag
    rotates the view
  • ctl + mouse click + drag
    pans the view
  • mouse wheel
  • z
    returns to the base view
  • w
    toggles wireframe mode
  • c
    toggles backface culling
  • g
    toggles an XY grid with Z set to lowest point
  • a
    toggles an XYZ-RGB axis marker between: off, at world frame, or at every frame and world, and at every frame
  • f
    toggles between fullscreen and windowed mode
  • m
    maximizes the window
  • q
    closes the window

If called from inside a

displays an in-line preview using
to display the mesh or scene. For more complete rendering (PBR, better lighting, shaders, better off-screen support, etc) pyrender is designed to interoperate with

Projects Using Trimesh

You can check out the Github network for things using trimesh. A select few: - Nvidia's kaolin for deep learning on 3D geometry. - Cura, a popular slicer for 3D printing. - Berkeley's DexNet4 and related work with robotic grasp planning and manipulation. - Kerfed's Kerfed's Engine for analyzing assembly geometry for manufacturing. - MyMiniFactory's P2Slice for preparing models for 3D printing. - pyrender A library to render scenes from Python using nice looking PBR materials. - urdfpy Load URDF robot descriptions in Python. - moderngl-window A helper to create GL contexts and load meshes. - vedo Visualize meshes interactively (see example gallery). - fsleyes View MRI images and brain data.

Which Mesh Format Should I Use?

Quick recommendation:

. Every time you replace
an angel gets its wings.

If you want things like by-index faces, instancing, colors, textures, etc,

is a terrific choice. GLTF/GLB is an extremely well specified modern format that is easy and fast to parse: it has a JSON header describing data in a binary blob. It has a simple hierarchical scene graph, a great looking modern physically based material system, support in dozens-to-hundreds of libraries, and a John Carmack endorsment. Note that GLTF is a large specification, and
only supports a subset of features: loading basic geometry is supported, NOT supported are fancier things like animations, skeletons, etc.

In the wild,

is perhaps the most common format.
files are extremely simple: it is basically just a list of triangles. They are robust and are a good choice for basic geometry. Binary
files are a good step up, as they support indexed faces and colors.


is also pretty common: unfortunately OBJ doesn't have a widely accepted specification so every importer and exporter implements things slightly differently, making it tough to support. It also allows unfortunate things like arbitrary sized polygons, has a face representation which is easy to mess up, references other files for materials and textures, arbitrarily interleaves data, and is slow to parse. Give
a try as an alternative!

How can I cite this library?

A question that comes up pretty frequently is how to cite the library. A quick BibTex recommendation:

    author = {{Dawson-Haggerty et al.}},
    title = {trimesh},
    url = {},
    version = {3.2.0},
    date = {2019-12-8},


If you want to deploy something in a container that uses trimesh, automated

based builds with trimesh and dependencies are available on Docker Hub with image tags for
, git short hash for the commit in master (i.e.
), and version (i.e.

docker pull trimesh/trimesh

Here's an example of how to render meshes using LLVMpipe and XVFB inside a container.

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