.3ds
Encyclopedia
3DS is one of the file format
s used by the Autodesk 3ds Max 3D modeling, animation and rendering software.
It was the native file format of the old Autodesk 3D Studio DOS (releases 1 to 4), which was popular until its successor (3D Studio MAX 1.0) replaced it in April 1996. Having been around since 1990 (when the first version of 3D Studio DOS was launched), it has grown to become a de facto
industry standard for transferring models between 3D programs, or for storing models for 3D resource catalogs (along with OBJ, which is more frequently used as a model archiving file format).
text-based formats.
The format is based in chunks, where each section of data is embedded in a block that contains a chunk identifier and the length of the data (to provide the location of the next main block), as well as the data itself. This allows parsers to skip chunks they don't recognize, and allows for extensions to the format.
The chunks form a hierarchical structure, similar to an xml DOM tree. The first two bytes of the chunk are its ID. From that value the parser can identify the chunk and decide whether it will parse it or skip it. The next four bytes contain a little-endian
integer that is the length of the chunk, including its data, the length of its sub-blocks and the 6-byte header. The next bytes are the chunk's data, followed by the sub-chunks, in a structure that may extend to several levels deep.
Below is a list of the most common IDs for chunks, represented in a hierarchical fashion depicting their dependencies:
text-file references
(based on documentation by Jim Pitts)
(based on documentation by Christophe Chabanois, Jim Pitts and Niklas Beisert)
File format
A file format is a particular way that information is encoded for storage in a computer file.Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for...
s used by the Autodesk 3ds Max 3D modeling, animation and rendering software.
It was the native file format of the old Autodesk 3D Studio DOS (releases 1 to 4), which was popular until its successor (3D Studio MAX 1.0) replaced it in April 1996. Having been around since 1990 (when the first version of 3D Studio DOS was launched), it has grown to become a de facto
De facto
De facto is a Latin expression that means "concerning fact." In law, it often means "in practice but not necessarily ordained by law" or "in practice or actuality, but not officially established." It is commonly used in contrast to de jure when referring to matters of law, governance, or...
industry standard for transferring models between 3D programs, or for storing models for 3D resource catalogs (along with OBJ, which is more frequently used as a model archiving file format).
Structure
3ds is a binary file format, therefore it is faster to load, and smaller than human-readableHuman-readable
A human-readable medium or human-readable format is a representation of data or information that can be naturally read by humans.In computing, human-readable data is often encoded as ASCII or Unicode text, rather than presented in a binary representation...
text-based formats.
The format is based in chunks, where each section of data is embedded in a block that contains a chunk identifier and the length of the data (to provide the location of the next main block), as well as the data itself. This allows parsers to skip chunks they don't recognize, and allows for extensions to the format.
The chunks form a hierarchical structure, similar to an xml DOM tree. The first two bytes of the chunk are its ID. From that value the parser can identify the chunk and decide whether it will parse it or skip it. The next four bytes contain a little-endian
Endianness
In computing, the term endian or endianness refers to the ordering of individually addressable sub-components within the representation of a larger data item as stored in external memory . Each sub-component in the representation has a unique degree of significance, like the place value of digits...
integer that is the length of the chunk, including its data, the length of its sub-blocks and the 6-byte header. The next bytes are the chunk's data, followed by the sub-chunks, in a structure that may extend to several levels deep.
Below is a list of the most common IDs for chunks, represented in a hierarchical fashion depicting their dependencies:
Shortcomings
It has been pointed out that, despite its popularity, the format may not be the most suitable for 3D data exchange. Some of the disadvantages mentioned are:- All meshes must be made of trianglesTriangle meshA triangle mesh is a type of polygon mesh in computer graphics. It comprises a set of triangles that are connected by their common edges or corners....
. - All texture filenames are limited to the 8.3 DOS format.
- The number of vertices and polygons per mesh is limited to 65536.
- Accurate vertex normals cannot be stored in the .3ds file. Instead "smoothing groupSmoothing groupIn 3D computer graphics, a smoothing group is a group of polygons in a polygon mesh which should appear to form a smooth surface. Smoothing groups are useful for describing shapes where some polygons are connected smoothly to their neighbors, and some are not...
s" are used so that the receiving program can recreate a (hopefully good) representation of the vertex normals. This is still a hold-over legacy for many animation programs today which started in the 1980s (3DS MAX, LightwaveLightWaveLightWave 3D is a high end computer graphics program developed by NewTek. The latest release of LightWave runs on Windows and Mac OS X.- Overview:...
and trueSpaceTrueSpaceTrueSpace is a freeware 3D computer graphics and animation software developed by Caligari Corporation, bought-out by Microsoft. As of May 2009, it has been officially discontinued, but with some 'unofficial support' up to February 2010, at least.- History :The company was founded in 1985 by Roman...
still use smoothing groups, and MayaMaya (software)Autodesk Maya , commonly shortened to Maya, is 3D computer graphics software that runs on Microsoft Windows, Mac OS and Linux, originally developed by Alias Systems Corporation and currently owned and developed by Autodesk, Inc. It is used to create interactive 3D applications, including video...
did up to v2.51). - Object, light and camera names are limited to 10 characters. Material names are limited to 16 characters.
- Directional light sources are not supported.
External links
web pages- 3DS parsing tutorial, by Amir "Genjix" TaakiAmir TaakiAmir Taaki is a British video game and computer software developer. Taaki is best known as the chairman of the Bitcoin Consultancy, as a Bitcoin project developer and for pioneering many open source projects.-Early years:...
- Spacesimulator.net - 3ds format file reader, loader, by Damiano Vitulli
- The Labs: 3DS File Format, by Jeff Lewis
- lib3ds: C library for loading/saving 3DS files, LGPL license
text-file references
(based on documentation by Jim Pitts)
(based on documentation by Christophe Chabanois, Jim Pitts and Niklas Beisert)