Spatial data products made available via free download via the Internet
(http, ftp) are found in a variety of common [and uncommon] formats. This
document serves to introduce the user to some of the commonly found data
formats.
ASCII
(American Standard Code for Information Interchange). Data in this format is simply a line-by-line listing of information in text format that takes on a geographical meaning when the listing contains positional coordinate information. Text information can be easily imported into most GIS and CAD-based software programs and it is this flexibility that drives storing some point data sets in this format.
ARC/INFO® Export format (.e00 extension)
An Export file is an ARC/INFO coverage that has been converted to an ASCII text file in order to make it accessible to ARC/INFO systems on different platforms. They are not intended for compression, but have become popular as exchange files. In order to convert an .e00 file to an ARC/INFO coverage or ArcView GIS shapefile, you must have ARC/INFO or the Import software distributed with ArcView GIS.
DEM (USGS)
A DEM file is organized into a series of three records, A, B, and C. The A record contains information defining the general characteristics of the DEM, including its name, boundaries, units of measurement, minimum and maximum elevations, number of B records, and projection parameters. Each B record consists of an elevation profile with associated header information, and the C record contains accuracy data.
DGN (Intergraph/Microstation)
Design files are sequential, variable-length files with variable-length records for the Design File Header, file set-up information, graphic elements, and non-graphic data. User-defined elements begin with the fourth element. Design files are typically designated with the extension ".dgn."
Drawing Interchange File (.dxf)
The Drawing Interchange file (DXF) format, is an industry standard interchange file format used to transfer data between CAD and GIS applications.
DWF
Design Wb Format developed by Autodesk... DWF preserves the fidelity and integrity of designs and allows anyone to access the complex design data without the originating design application. DWF files are easy to create and post to the web, and they support up to 60 million dpi. DWF data can be created using Autodesk products and the DWF Composer or read using the Free DWF Reader. See www.autodesk.com/dwf
ESRI_Coverage
A coverage is a proprietary vector format used by ESRI software. Coverages are the original storage format for ArcInfo. Coverages are a collection of files located in multiple directories.
ESRI Shapefiles (.shp)
A shapefile stores non-topological geometry and attribute information for the spatial features in a data set. A shapefile consists of a set of 3 mandatory files, along with several optional files. Each file in the set shares the shapefile name with a different extension. The main file (*.shp) stores the geometry and must always have an index file (*.shx). A dBASE file (*.dbf) stores all the attributes of the shapes in the main file. Additionally, a projection file (*.prj) stores the projection information.
ESRI Interchange (.e00)
The ESRI E00 interchange data format allows all spatial and descriptive information for vectors and rasters to be combined into a single ASCII file. The file can be used to move themes into and out of ESRI software.
ESRI GRID
The Arc/Info Binary Grid format is the internal working format of the ESRI Arc/Info Grid product. It is also usable and creatable within the spatial analyst component of ArcView 3.x. It is a tiled format with run length compression capable of holding raster data of up to 4 byte integers or 4 byte floating data.
GDF
GDF means Geographic Data Files, It is a standard data exchange format and a data model (a complex data model). It is used to describe road networks & road-related data and is an international standard ISO/TC204 / CEN/TC 278. The GDF 3 and GDF 4 specifications can be found HERE
Geodatabase
This is a new data model introduced by ESRI with ArcInfo 8. It consists of a comprehensive Access format database (.mdb) with different interrelated features. It allows to assign “behavior” to data by relating different feature classes inside a single database file.
GeoTIFF
The Tagged Image File Format (TIFF), developed by Aldus Corporation, is an industry standard for data storage and data transfer across operating system environments and applications. A GeoTIFF takes the TIFF format a step further including geospatial information (such as projection, datum, etc.) in the file. USGS DRGs are commonly found as TIF or GeoTIFF format.
JPEG 2000
JPEG 2000 is a new image coding system that uses state-of-the-art compression techniques based on wavelet technology. Its architecture should lend itself to a wide range of uses from portable digital cameras through to advanced pre-press, medical imaging and other key sectors. See http://www.jpeg.org/jpeg2000/
MIF (MapInfo Interchange format)
Proprietary data format used by MapInfo desktop GIS. Often associated with MIF/MID pairs of data. MIF/MID is commonly used to translate to/from MapInfo, whereas .TAB data is used directly by MapInfo.
MrSID (.sid)
MrSID is an acronym for Multi-resolution Seamless Image Database, a powerful wavelet-based image compressor, viewer and file format for massive raster images. These data can be viewed in a variety of GIS software applications. For more info see www.lizardtech.com
SDTS
Developed by the USGS, the purpose of the SDTS is to promote and facilitate the transfer of digital spatial data between dissimilar computer systems, while preserving information meaning and minimizing the need for information external to the transfer. Details HERE
SHP
ESRI's .shp format, also known as "shape format" or "shapefiles," is used with ArcView, a popular GIS package of the early 1990's. Shape format has been openly published by ESRI and is widely used for data interchange in GIS. Shapefiles usually consist of three similarly named files with differing extensions: a .shp, .shx and a .dbf file. The .dbf file is a dBase database system format file that is used to store data attributes for the drawing. (Soure: Manifold.net) See the specifactions HERE
TIFF with a World File (.tif, .tfw)
The Tagged Image File Format (TIFF), developed by Aldus Corporation, is an industry standard for data storage and data transfer across operating system environments and applications. It is one of the most versatile bitmaps available. A world file (.tfw) accompanying the .tif file contains spatial information about the data. These are common for USGS DRG data (aka. topo quads)
TIGER/Line (.tgr)
Topologically Integrated Geographic Encoding and Referencing system (TIGER) - see US Census bureau
USGS_dem (.dem)
United States Geological Survey Digital Elevation Model data format. These data can be viewed in a variety of GIS software applications. Additional information about the USGS DEM format can be found from usgs.gov.
USGS_doq (.sws, .ses, .nws, .nes)
Data in this format are in a native USGS single-file format. They are really a BIL format without a separate header file. You can't view images with these extensions directly in ArcView and/or ArcInfo. However, the Washington State Geospatial Data Archive has excellent information about how to manipulate these images so that you can view them in ArcView and/or ArcInfo.
Common GIS/CAD file extensions (Source: ESRI Tech. Support)
adf - ARC/INFO coverage data file
agf - Atlas GIS native binary geodataset file
ain - attribute index file
aih - attribute index file
alg - ER Mapper algorithm
aml - ARC/Info AML file
apr - ArcView Project File (ODB format)
avl - legend template file (ODB format)
avp - palette file (ODB format)
ave - Avenue script
avx - ArcView extension file (ODB format)
ai - Adobe Illlustrator picture file
bat - DOS batch file
bil - image file (band interleaved by line)
bip - image file (band interleaved by pixel)
blw - world file for bil image
bmp - Windows bitmap image file
bpw - world file for bip or bmp images
bsq - image file (band sequential)
bqw - world file for bsq image
c - C programming language source code filename
cat - UNIX hyperhelp supporting file
cgm - Computer Graphics Metafile
cls - geocoding classification file
cnt - help file contents
dat - generic data file extension dat - INFO attribute file
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