OBJ (.obj) import/export

The OBJ file format is a simple data-format that represents 3-D geometry alone include only the position of each vertex, the UV position of each texture coordinate vertex, normals, and the faces that make each polygon defined as a list of vertices, and texture vertices. Vertices are stored in a counter-clockwise order by default, making explicit declaration of normals unnecessary.

Import

To open, import or insert a file

From the File menu, click Open, Insert, or Import.
In the dialog box, select a supported file type.
Click Open and configure the settings.
When you open a non-3dm file and save the model, its filename will be the default 3dm filename.

OBJ Import Options

Import OBJ groups as

Nothing

Groups

Layers

Object names

Import OBJ objects

Import as morph target only

Reverse group order

Ignore textures

Set display color from OBJ material color

Enable to import material colors in the OBJ file as object display colors. Otherwise, the default color is used.

Map OBJ Y to Rhino Z

Split 32-bit textures into separate files

Always use these settings. Do not show this dialog again.

Saves the current settings and turns off the dialog display.

To turn the message back on

Click the Options button in the appropriate Save, Export, Open, Import, or Insert dialog box.

Export

To save as or export a Rhino model

On the File menu, click Export Selected or Save As.
In the dialog box, the Files of type list displays the currently supported file types for export.
In the Files of type box, select the supported file type.
In the File name box, select or type a file name.
Specify what is to be saved.

Options
Save small	Though clearing the render meshes makes the file smaller, it will shade and render more slowly the next time you open the file.
Save geometry only	Saves geometry objects only. No layers, materials, properties, notes, or units settings are saved. This is similar to exporting the objects. A new file is made, but it does not become your active Rhino model.
Save textures	Embeds external textures used by materials, environments and decals into the model.
Save plugin data	Saves data attached to objects or the document by plug-in applications.

If the export can be configured, click the Options button to specify export settings.
Mesh file types export NURBS surfaces as meshes either with the specified meshing options, or the document render mesh settings.

OBJ Export Options

Geometry

Save surfaces, polysurfaces and extrusions as

NURBS objects

Rhino curves and surfaces export as NURBS curves and surfaces.

Polygon mesh objects

Surfaces are approximated with polygon mesh objects. In the Create mesh from NURBS object dialog box, set the way Rhino creates a polygon mesh from the NURBS geometry. Curves do not export.

Save surface trim curves as

Polylines

When exporting NURBS surfaces, polylines approximate the trimming curves. The geometry does not match the accuracy of exporting trims as curves. This option was originally included for exporting to Alias. Now you should be able to use IGES for exporting to Alias instead.

Curves

When exporting NURBS surfaces, the trim curves are NURBS. NURBS trim curves provide more accuracy than exporting trims as polylines.

Formatting

End-of-line character

Windows (CRLF)

Return + line feed.

Mac OS X, Unix (LF)

Line feed only.

Mac OS 9 (CR)

Return only.

__ Significant digits

Export material definitions

Creates an .mtl file with the same name as the .obj file. The .mtl file contains one material definition per object. There are also references to these materials added to the .obj file.

This option sets OBJ diffuse material to the object's display material if there is no render material assigned.

Use display color for objects with no material set

An object with no material assigned exports with the default material (enabled), otherwise with a material using the object's display color (disabled).

Convert white space in material names to underscores

Map Rhino Z to OBJ Y

Translates the exported model from a z up orientation to a y-up orientation.

Wrap long lines

Checking this option may cause downstream applications fail to read the output file. Uncheck this option if you are not sure whether the target application can handle line wraps.

Naming

Export Rhino object names

Exports object names.

Do not export object names

As OBJ groups (Use for export to 3dsMax)

As OBJ objects

Export Rhino layer/group names

These settings make it possible to export data to programs that do not support nested grouping. The OBJ import plug-in for 3ds max is one example. To export to 3ds max, select Do not export layer/group names.

Do not export layer/group names

Layers as OBJ groups

Groups as OBJ groups

Sort by OBJ groups

OBJ is an ASCII format and does not support multi-byte character sets, such as Chinese, Japanese and Korean. Multi-byte character names will not remain in OBJ export.

Curves

Export polylines as

Degree 1 bspline

One OBJ line with multiple OBJ vertices

Multiple OBJ lines with 2 OBJ vertices

Mesh

Vertex welding

Unmodified

Welded

Exports a single vertex for any given location (i.e., the topological vertex) but exports all of the normals and texture coordinates associated with the mesh vertex.

Completely unwelded

Unwelds the entire mesh before exporting it

SubD meshing

From SubD surface

Converts SubD surfaces into meshes with the selected meshing density.

Extra coarse

Coarse

Medium

Fine

Extra fine

From SubD control net

Extracts SubD control nets as meshes.

NGons

None

Converts NGons into triangle or quad mesh faces.

Preserve

Keeps NGons, but do not convert any mesh faces into NGons.

Create

Keeps NGons, and converts each planar region (red) into an n-gon. The planar region (blue) with an inner boundary will not be converted.

___Minimum face count

Planar regions with mesh faces less than this number will not be converted into NGons.

Export texture coordinates

Export vertex normals

Export vertex colors

0.0-1.0

Saves RGB values of vertex colors with the range of 0 to 1.0.

0-255

Saves RGB values of vertex colors with the range of 0 to 255.

If you want to bake textures in assigned materials into vertex colors, make a mesh and use ComputeVertexColors first prior to exporting.

Export open meshes

Export as triangles

Converts quads to triangles like what the TriangulateMesh command does.

Use render meshes

Enable to export objects with document mesh settings. Polygon mesh export options will not display. Object custom meshes will save to the OBJ file.

Disable to export objects with the polygon mesh export options. Object custom meshes will not save to the OBJ file.

Always use these settings. Do not show this dialog again.

Saves the current settings and turns off the dialog display.

To turn the message back on

Click the Options button in the appropriate Save, Export, Open, Import, or Insert dialog box.

Export notes

Attempting to export invalid objects will cause the export to fail. Use the SelBadObjects command to find invalid objects before exporting.
Assign a material name to an object in Material Properties. This material name is exported for use by the renderer.
Layer names and object names export into the OBJ file as OBJ group names. Spaces in the layer or object names are converted into underbar (_) characters.