Importing and Exporting 3DS Files

The 3DS format is native to the original DOS-based 3D Studio modeling and animation application. 3DS offers a direct way to export simpler SketchUp models into a wide range of 3D modeling packages. Because 3DS preserves material assignments, texture mapping, and camera position, 3DS can often transfer ideas that you generate in SketchUp to other programs with greater fidelity than CAD formats can.

Importing 3DS files

Before importing a 3DS file into SketchUp, check whether the file has textures that you want to import. If so, make sure the texture files are saved in the same folder as the 3DS file. Once you are ready, follow these steps:

1. Select File > Import.
2. Select the 3DS file you want to import.
3. Click Options and adjust the following as needed:
   1. Merge Coplanar Faces – Selecting this option removes triangular lines from coplanar faces when importing.
   2. Units – Select to choose the unit of measure used to import your 3DS geometry. SketchUp only recognizes faces larger than .001 square inches. We recommend using a larger unit type, like feet or inches, if you aren’t sure what unit type the original uses. You can always resize the model after importing.
4. When you are satisfied with your options, click OK.
5. Click Import to begin importing your file. Large files may take some time.

Exporting 3DS files

Exporting a file to 3DS requires a SketchUp Go, Pro, or Studio subscription. A few things to keep in mind before you export your SketchUp model to 3DS:

• Make sure the front side of each face in your model is facing outward.
• Show all the geometry you want to export. Hidden entities won’t export.
• The 3DS format doesn’t support tag functionality. If you want to retain your tags, you may want to use another format.

When your SketchUp model is ready to export to 3DS, follow these steps:

1. Select File > Export > 3D Model.
2. Navigate to the location where you want to save your file.
3. Under Export Type select 3DS File (*.3ds).
4. By default, the 3DS file has the same name as your SketchUp model. You can change the file name if you like in the File Name box.
5. Click Options. Choose the options (see below) you want and click OK.
6. Click Export.

3DS Export Options

There are a few options you can choose from when exporting a file to 3DS.

Under Geometry you can choose the following options:

• Use the Export drop-down to choose how you want to organize meshes in the exported 3DS file:
  • Full Hierarchy – Creates a mesh for each top-level nested component and group and for non-grouped entities based on the connection of faces. These meshes are organized according to their place in the component and group hierarchy.
  • By Tag – Creates separate meshes based on how faces are connected and on the tags they use.
  • By Material – Creates separate meshes for all faces that are connected and have the same material. These meshes are then organized based on their materials.
  • Single Object – Exports your SketchUp model as a single 3DS mesh. The 3DS format limits meshes to 65,536 vertices and faces and may export more than one mesh if the exported model exceeds this limit.
• Export Only Current Selection – Only exports selected geometry, rather than the entire model.
• Export Two-Sided Faces – SketchUp will export faces twice, once for the front and once for the back, and welds the front and back faces together according to the logic for texture mapping and welding. This option doubles the number of polygons in the exported 3DS file and can slow down rendering.
• Export Stand-Alone Edges – The 3DS format doesn’t support stand-alone lines the same way SketchUp does. Selecting this option transforms stand-alone edges into thin rectangles that look like stand-alone lines in the 3DS file.

Under Materials you can select the following options:

• Export Texture Maps – If selected you can choose how materials are applied to your exported mode:
  • Preserving Texture Coordinates – SketchUp will preserve textures by breaking up geometry so that each coplanar group has its own vertices. In other words, vertices aren’t welded together, and faces aren’t smoothed. Vertices are welded when welded faces have identical texture maps.
  • Welding Vertices – This option makes sure welding and smoothing get top priority. If two faces share a vertex but have different texture maps, only one texture map is preserved in the exported file.

Under Camera, the Generate Cameras from Pages option creates a camera view for each page or scene in the model.

Under Scale, the Units options allow you to choose the unit of measurement used in the exported file.

Known Issues When Exporting to 3DS

Because 3DS is an older format, transitioning to newer software and operating system contexts isn’t always easy. Here are a few known issues you may encounter after you import your 3DS file into another program:

• Textures and materials exported with the Export Two-Sided Faces checkbox selected can become flipped in certain applications, such as Maya. A 3DS mesh does not store any normal data, so the target system must compute the model’s normals. Some importers might compute the normals incorrectly, resulting in flipped textures.
• Truncated texture map file names are common. Because the 3DS format was designed in the DOS age, it’s not capable of storing texture file names that exceed the 8.3 DOS character limit. If you’ve used modern OS file names (and you probably have), SketchUp creates unique names for each texture by adding unique suffixes to file names. For example, a file named corrugated metal.jpg is described in the 3DS file as corrugat.jpg. Any other files that use the same first six letters are truncated, and the suffix 01, 02, and so on, is added.
• 3DS format can’t store an orthographic camera. This format is simulated through a perspective camera with a very small field of view or a very large lens length. The eye point is moved as far away as possible to yield the same width and height of the projection plane. Certain applications might have problems with a small field of view.