What to Expect When You Import Exchange Formats

When you download an exchange format with the intention of importing it into your application, there are a few things you should know about these files.

An exchange format does not hold all the information that a native file format does. Although you can often import the original model's topology, mapping, and textures with some degree of accuracy, an imported exchange format by nature doesn't contain all the original model's information.

How to Use This Guide

  1. Answer the questions listed below, and keep the answers in mind as you read on.
  2. Read the General Limitations section, and use this information to choose a file format to import.
  3. Optional: After you choose a file format to import, read general information about that file format in the Exchange Formats article.
  4. Look under Specific Known Exchange Format Issues to see if there are any known issues for the import you plan to perform.

Important Questions

Answer these questions to help you choose an exchange file format to import.

Is the native format available for your application? If so, use the native file format and not an exchange format.

Do you expect to import rigging and animation? If so, you will need to import the FBX file format, as it is the only one that might contain this information. In any case, you should contact Support before buying so they can perform a test conversion and ensure rigging and animation will successfully import to your application from the FBX file.

Which is more important to you, retaining the same topology as the original native file, or retaining the same mapping and textures? With some exchange file formats, you will need to make a choice between topology and mapping. Some exchange formats import as completely triangulated meshes even if the native file is constructed from quads. Another format might import with the topology intact, but the textures are no longer referenced by the model.

General Limitations

The following limitations hold regardless of the application you use to import the exchange format.

Topology Limitations

OBJ, FBX - Might import quad and ngon topology as triangles depending on how the original model was created.

3DS - Geometry always consists of triangles only. Because most applications have a limit of 64K faces when exporting 3DS files, a 3DS file for a large or complex model might not include all the geometry or might not work altogether.

DXF - Limit of 32K faces. DXF models tend to be heavily triangulated, and faces are often flipped.

STL - Single-sided geometry is not held.

Materials and Textures

OBJ, FBX, 3DS -  Complex materials, or those special to the original application, might not load or be complete depending on how the model was created/exported and also how your application reads the data upon import. Example: Mental Ray materials from 3ds Max do not export accurately to any exchange format. A complex, layered bump map or displacement map will not export accurately. Procedural textures do not export accurately. However, a Standard material from 3ds Max with a single Diffuse Bitmap texture will usually export perfectly.

3DS - An imported 3DS file will often give an error of "Textures not found" when the textures actually do exist, but in order to make the textures appear on the model each one must be reselected one at a time. This happens because the 3DS format truncates all texture names referenced by materials to 8 characters. For example, if a material references a series of textures called BoatDiffuseSide.JPG, BoatBumpSide.JPG and BoatSpecularSide.JPG in the native application, upon export to 3DS the texture references within the model file are truncated to BoatDiff.JPG, BoatBump.JPG, and BoatSpec.JPG. The filenames themselves are not truncated, just the references within the 3DS file. If you imported such a model, it would look for these truncated file names and would not be able to find them. You can solve the problem by reselecting each map manually, but this can be time-consuming if there are a lot of textures.

DXF - Contains no material or texture information.

STL - Contains no material or texture information.

Transparency and Opacity

OBJ, FBX, 3DS - Opacity/transparency is often reversed upon export. This means you will need to change various material settings for alpha and transparency within your application, and invert any black/white maps used to define transparency.

Subdivision

Some exchange formats you'll find at TurboSquid were exported by the artist with subdivision already applied, so any import of the model will have this more detailed geometry already baked in. If you encounter this situation, and you prefer to have the base mesh without subdivision, please contact Support and we will endeavor to do a base mesh export for you.

Specific Known Exchange Format Issues

These issues are in addition to any limitations of the file format as listed above.

FBX / DAE to Lightwave - Smoothing information is lost; normals might be flipped depending on how model was originally made.

FBX / DAE to Softimage - Textures need to be remapped to a local folder.

OBJ to 3ds Max - 3ds Max will not open OBJ  files exported from native Blender files.

OBJ to Cinema 4D - No materials, textures, or UV mapping will import. The Riptide plug-in for Cinema 4D can sometimes read OBJ files successfully.

OBJ to Lightwave - Normals might be flipped depending on how model was originally made.

OBJ to Softimage - Textures need to be remapped to a local folder.

3DS to Maya - Maya does not include a 3DS importer. There are plug-ins available that can achieve this.

Related Topics

Solids Conversions

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