Wavefront OBJ
Reference
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OBJ is a widely used de facto standard in the 3D industry. The OBJ format is a popular plain text format, however, it has only basic geometry and material support.
Note
There is no support for armatures, lights, cameras, empty objects, parenting, or transformations. See Compatibility for more information.
Usage
Export geometry and curves to the OBJ format.
Exporting
Properties
Animatioon
- Animation
Exports a numbered OBJ for each frame from the start to the end frame. Please be aware that this can take quite a long time.
- Frame Start, End
The first and last frame to export, used to determine the range of exported frames.
Object Properties
- Axis Forward, Up
Since many applications use a different axis for ‘Up’, there are axis conversion settings, Forward and Up axis – By mapping these to different axis you can convert rotations between applications default up and forward axis.
Blender uses Y Forward, Z Up (since the front view looks along the +Y direction). For example, its common for applications to use Y as the up axis, in that case -Z Forward, Y Up is needed.
- Scale
Global scale to use on export.
- Selected Only
Only export the selected objects. Otherwise export all objects in the scene.
- Properties
For properties that have different settings for the viewport/final render pick which is used for output. One example where this is important is the Subdivision Surface Modifier.
- Viewport (Default)
Use viewport properties.
- Render
Use final render properties.
Geometry Export
- UV Coordinates
Write out the active UV layers coordinates from Blender.
- Normals
Write out Blender’s face and vertex normals (depending on the faces smooth setting).
Mostly this isn’t needed since most applications will calculate their own normals but to match Blender’s normal map textures you will need to write these too.
- Materials
Write out the MTL-file along with the OBJ. Most importers that support OBJ will also read the MTL-file.
- Triangulated Mesh
Write out quads as two triangles. Some programs only have very basic OBJ support and only support triangles.
- Curves as NURBS
Write out NURBS curves as OBJ NURBS rather than converting to geometry.
Grouping
- Object Groups
Write out each Blender object as an OBJ object.
Note
Note that as far as Blender is concerned there is no difference between OBJ Groups and Objects, this option is only included for applications that treat them differently.
- Material Groups
Create OBJ groups per material.
- Vertex Groups
Export the name of the vertex group of a face. It is approximated by choosing the vertex group with the most members among the vertices of a face.
- Smooth Groups
Write Blender’s sharp edges as smooth groups.
- Bitflag Groups
Generate Bitflags for smooth Groups.
Importing
Importing OBJ-files is currently handled by a python importer which is included as an addon. It’s documentation can be found here: OBJ Importer </addons/import_export/scene_obj>.
Compatibility
NURBS surfaces, text3D and metaballs are converted to meshes at export time.