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Exporting OBJ Files

If you’re a SketchUp Pro user, you can export files in the OBJ format.

Wavefront Technologies developed the OBJ file format for its Advanced Visualizer software, and over time, other 3D software developers have adopted the open OBJ format. OBJ files are text-based and support free-form and polygonal geometry. When you export an OBJ file from SketchUp, an additional .mtl file describes materials defined in the .obj file.

In the upcoming sections, you find out what the OBJ format does and doesn’t support and how to export an OBJ file from SketchUp Pro.

Table of Contents
  1. Understanding what OBJ does and doesn’t support
  2. Exporting an OBJ file

Understanding what OBJ does and doesn’t support

Before you export a SketchUp model to the OBJ file format, it’s helpful to know what the format does and doesn’t support. Here’s an overview of what you can expect from your exported OBJ files:

  • No spaces are allowed in file names. OBJ files don’t support spaces in their file names. When you export an OBJ file, SketchUp replaces any space with an underscore (_).
  • Each SketchUp face exports as one polygon (unless you tell SketchUp otherwise). If the application in which you want to use the OBJ file expects triangulated faces, you can select the Triangulate All Faces option when you export the file to avoid triangulation errors, such as missing or reversed polygons.
  • OBJ supports a flat set membership hierarchy, not a tree hierarchy. In a flat set membership hierarchy, the format identifies what objects belong to a set but can’t tell whether one set belongs to another set. This is different from the tree hierarchy you see in SketchUp’s Outliner, which indicates, for example, that a cushion is a subcomponent of a sofa or that a leg component is nested inside a chair component.
  • SketchUp outputs polygon faces only. SketchUp doesn’t support the output of NURBS or any advanced OBJ entities.

Note: If PNG and JPG images, which are included in an OBJ export from SketchUp, don’t appear in Maya, this problem is due to a known bug in Maya for Mac OS X.

Exporting an OBJ file

To export an OBJ file from SketchUp Pro, follow these steps:

  1. Select File > Export > 3D Model. The Export Model dialog box appears.
  2. Navigate to the location where you want to save your OBJ file.
  3. In the Export TypeSave as type drop-down list, select OBJ File (*.obj).
  4. (Optional) Rename your file in the File Name text box.
  5. (Optional) Click the Options button. The OBJ Export Options dialog box appears. Select your desired options, which are explained in the following list, and click OK to return to the Export Model dialog box.
  6. Click Export and your OBJ file is saved in the location you selected.
  1. Select File > Export > 3D Model. An export dialog box appears.
  2. Navigate to the location where you want to save your OBJ file.
  3. In the Format drop-down list, select OBJ File (*.obj).
  4. (Optional) Rename your file in the Save As text box.
  5. (Optional) Click the Options button. The Export Options dialog box appears. Select your desired options, which are explained in the following list, and click OK to return to the export dialog box.
  6. Click Export and your OBJ file is saved in the location you selected.

When you export an OBJ file from SketchUp Pro, you can choose from the following options:

  • Export Only Current Selection: If you make a selection in your model before you begin the export process, selecting this box exports only the selected geometry. When this option is deselected, the whole model is exported.
  • Triangulate All Faces: Select this option to break the output into triangles instead of multisided faces.
  • Export Two-Sided Faces: When you select this option, faces are exported twice: once for the front and once for the back. Although this doubles the number of polygons in the exported file, the model will look more like it appears in SketchUp. Both faces will render, and materials applied to the front and back faces are preserved.
  • Export Edges: When you select this checkbox, SketchUp line entities are exported as OBJ line entities. If you leave this checkbox deselected, edges are ignored. Usually, this checkbox is deselected because most applications ignore edges when importing OBJ files.
  • Export Texture Maps: Select this checkbox to export textures applied to faces with your OBJ file.
  • Swap YZ Coordinates (Y Is Up): This option does just what it says: swaps the Y (green) axis and the Z (blue) axis so that the Y axis points up. For some applications, this orientation is the default. To leave the default orientation (Z is up), leave this checkbox deselected.
  • Units: Select an option from the drop-down list to set the unit size in the OBJ file. If you want the units to be the same as those in your SketchUp model, you can leave Model Units (the default option) selected.
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