A spatial data file is a single-user geodatabase

Geodatabase

A geodatabase is a spatial database designed to store, query, and manipulate geographic information and spatial data of low dimensionality. It is a specialized type of spatial database often with optimizations for 2 and 3 dimensions, raster data and Euclidean distance.Within a spatial database,...

 file format

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...

 developed by Autodesk

Autodesk

Autodesk, Inc. is an American multinational corporation that focuses on 3D design software for use in the architecture, engineering, construction, manufacturing, media and entertainment industries. The company was founded in 1982 by John Walker, a coauthor of the first versions of the company's...

. The file format is the native spatial data storage format for Autodesk GIS programs MapGuide and AutoCAD Map 3D. The current format version is SDF3 (based on SQLite3), which is a single file. Prior versions of the format required a spatial index file (SIF), with an optional key index file (KIF) to speed access to the file.

The SDF file format can be created and manipulated using an OSGeo

Open Source Geospatial Foundation

The Open Source Geospatial Foundation , is a non-profit non-governmental organization whose mission is to support and promote the collaborative development of open geospatial technologies and data. The foundation was formed in February 2006 to provide financial, organizational and legal support to...

 FDO Provider for SDF, which is open source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 software. Beyond Autodesk's products, products that can read/write the format are FME from Safe Software, Fdo2Fdo, and the FdoToolbox.

The SDF format design uses low-level storage components of SQLite

SQLite

SQLite is an ACID-compliant embedded relational database management system contained in a relatively small C programming library. The source code for SQLite is in the public domain and implements most of the SQL standard...

 using a flat binary serialization (binary large object

Binary large object

A blob is a collection of binary data stored as a single entity in a database management system. Blobs are typically images, audio or other multimedia objects, though sometimes binary executable code is stored as a blob...

s). However, the relational aspects are not present, thus the format cannot be opened with any software designed specifically for SQLite. The format supports multiple feature classes per file and multiple geometry properties per feature class. Each geometry property is indexed using an R-tree

R-tree

R-trees are tree data structures used for spatial access methods, i.e., for indexing multi-dimensional information such as geographical coordinates, rectangles or polygons. The R-tree was proposed by Antonin Guttman in 1984 and has found significant use in both research and real-world applications...

. It is optimized for fast spatial reading of large datasets in single-writer multiple-reader scenarios.

External links

• SDF Loader provided by Autodesk to convert from Shapefile
  Shapefile
  The Esri Shapefile or simply a shapefile is a popular geospatial vector data format for geographic information systems software. It is developed and regulated by Esri as a open specification for data interoperability among Esri and other software products.Shapefiles spatially describe geometries:...
  
  s and other formats