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OBJ (.obj)

Background & Context

    • Wavefront OBJ format.
    • 3D geometry format.
    • Used for storage and exchange of 3D geometry definitions.
    • Native format of the Wavefront application.
    • Stores a geometry as a collection of line, point, and polygon primitives and their properties.
    • Can store face color information.
    • ASCII format.
    • Developed by Alias Wavefront.
    • Stores a single geometry.

Import & Export

  • Import["file.obj"] imports an OBJ file as a MeshRegion object representing the surface.
  • Import["file.obj",elem] imports the specified element from an OBJ file.
  • The import format can be specified with Import["file","OBJ"] or Import["file",{"OBJ",elem,…}].
  • Export["file.obj",expr] exports a 3D mesh-based geometric region to a binary OBJ file. The expr can be any region that is ConstantRegionQ or a Graphics3D object.
  • Export["file.obj",expr,{opt1->val1,…}] exports expr with the specified options for the file format.
  • The export format can be specified with Export["file",expr,"OBJ"] or Export["file",expr,{"OBJ",opt1->val1,…}].
  • See the following reference pages for full general information:
  • Import, Exportimport from or export to a file
    CloudImport, CloudExportimport from or export to a cloud object
    ImportString, ExportStringimport from or export to a string
    ImportByteArray, ExportByteArrayimport from or export to a byte array

Import Elements

  • General Import elements:
  • "Elements" list of elements and options available in this file
    "Summary"summary of the file
    "Rules"list of rules for all available elements
  • Data format representation elements:
  • "VertexData"list of vertex coordinates
    "PolygonData"the polygon elements in indexed form
    "VertexNormals"normal vectors corresponding to the vertices
  • Geometry representation elements:
  • "BoundaryMeshRegion"boundary mesh representation of the solid
    "MeshRegion"mesh representation of the surface
  • Graphics representation elements:
  • "Graphics3D"OBJ file represented as a Graphics3D object
    "GraphicsComplex"OBJ file as a GraphicsComplex object
    "PolygonObjects"list of polygon primitives given in absolute coordinates
  • Import and Export use the "MeshRegion" element by default for OBJ files.

Examples

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Basic Examples  (2)

Import a 3D model from OBJ as a MeshRegion object:

Wolfram Language code: Import["ExampleData/seashell.obj"]

Summary properties of the model:

Wolfram Language code: Import["ExampleData/seashell.obj", "Summary"]

Export a 3D model with transparent faces:

Wolfram Language code: Export["model.obj", [image]]

Print the raw textual contents of the file:

Wolfram Language code: FilePrint[%]

Scope  (11)

Import  (6)

Import works on an ASCII OBJ file:

Wolfram Language code: Import["ExampleData/seashell.obj"]

Any accessible URL:

Wolfram Language code: Import["http://exampledata.wolfram.com/vase.obj"]

Stream:

Wolfram Language code: str = OpenRead["ExampleData/chain.obj"]
Wolfram Language code: Import[str]
Wolfram Language code: Close[str]

Import automatically detects OBJ files:

Wolfram Language code: Import["http://exampledata.wolfram.com/gear.3"]

Import provides access to elements in the OBJ file:

Wolfram Language code: Import["ExampleData/seashell.obj", "Elements"]

Import works on large files:

Wolfram Language code: Import["http://exampledata.wolfram.com/turtle.obj"] // MeshCellCount//AbsoluteTiming

Export  (5)

Export works on 3D graphics:

Wolfram Language code: Export["model.obj", [image]]

Special regions:

Wolfram Language code: Export["sphere.obj", Sphere[]]

Formula regions:

Wolfram Language code: Export["ball.obj", ImplicitRegion[x ^ 2 + y ^ 2 + z ^ 2 ≤ 1, {x, y, z}]]

Mesh regions:

Wolfram Language code: Export["pyramid.obj", MeshRegion[{{-1, -1, 0}, {1, -1, 0}, {1, 1, 0}, {-1, 1, 0}, {0, 0, 1}}, Pyramid[{1, 2, 3, 4, 5}]]]

ASCII OBJ file:

Wolfram Language code: Export["model.obj", [image]]

Import Elements  (10)

"BoundaryMeshRegion"  (1)

Give a boundary mesh region:

Wolfram Language code: Import["ExampleData/chain.obj", "BoundaryMeshRegion"]

"CoordinateTransform"  (1)

The coordinate system used by the OBJ format is identical to the Wolfram Language:

Wolfram Language code: Import["ExampleData/chain.obj", "CoordinateTransform"]

"Graphics3D"  (1)

Give the Graphics3D object:

Wolfram Language code: Import["ExampleData/chain.obj", "Graphics3D"]

"GraphicsComplex"  (1)

Give the GraphicsComplex object:

Wolfram Language code: Import["ExampleData/chain.obj", "GraphicsComplex"]//Short

"MeshRegion"  (1)

Give a mesh region:

Wolfram Language code: Import["ExampleData/chain.obj", "MeshRegion"]

"PolygonData"  (1)

Give the polygon elements in indexed form:

Wolfram Language code: Import["ExampleData/chain.obj", "PolygonData"]

"PolygonObjects"  (1)

Give the list of Polygon primitives given in absolute coordinates:

Wolfram Language code: Import["ExampleData/chain.obj", "PolygonObjects"]

"Summary"  (1)

Give the summary of properties:

Wolfram Language code: Import["ExampleData/chain.obj", "Summary"]

File size:

Wolfram Language code: %["FileSize"]

"VertexData"  (1)

Give the vertex coordinates:

Wolfram Language code: Import["ExampleData/chain.obj", "VertexData"]//Short

"VertexNormals"  (1)

Give the vertex normals:

Wolfram Language code: Import["ExampleData/chain.obj", "VertexNormals"]