Compression Formats:

 

Background

These formats are used for efficient storage or transmission of data, using a variety of compression algorithms in software programs that range from open-source to commercial. The excellent resource link below covers the subject very thoroughly. We include here also two formats that do not actually reduce data volume, but are used for transmission of multiple files concatenated to a single file, so in effect they reduce transmission overhead.

Compression Formats and Software

This table summarizes the most important formats/software encountered often in marine work.


Format Name Associated Software Documentation Comments
Zip (ZIP) WinZip, among at least a dozen others; Microsoft and Apple include built-in Zip support
  • Some GIS programs can work directly from the Zip files, performing the decompression automatically
  • This is the actual format used for KMZ files, so the extension should be changed back to ZIP in order to inspect the file contents.

Gzip (GZ) gzip

Ocean Data View must work directly from the gz versions of World Ocean Database files, so they should not be unzipped beforehand



Bzip (BZ2) Bzip2

Commonly used by US NASA for data file distribution




Concatenation Formats and Software

This table summarizes the most important formats/software encountered often in marine work.


Format Name Associated Software Documentation Comments
TAR (*.tar) tar (UNIX utility) Wikipedia: Tar file Tar files can also be zipped after concatenation, so *.tar.zip and *.tar.gz files are often encountered, called "tar balls".  Most commercial de-compression programs can handle these.
E00 (*.e00)
  • ArcGIS and some other GIS programs
  • Import71 - Free utility from ESRI
ESRI shapefile and coverage file "interchange" format.  Contains any of about 15 different specifically formatted types of geographic data, strung together much like a tar file.  Import71 converts the file to either a shapefile or a coverage.