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Section 3: Archiving GIS Datasets#

3.1 Preparing to Archive: Files and Formats#

As GIS data often incorporates data from a variety of sources the formats that are safest for digital preservation vary with the type of information contained within a file. In this section, recommendations are given for formatting of GIS files, databases, images, documentation, and metadata.

3.1.1 GIS Files#

As highlighted in a 2009 DPC Technology Watch Report, "Attempts at defining a universal data model for geospatial data have been made (for example the Spatial Data Transfer Standard (SDTS)...but have not achieved widespread adoption. As a consequence, it is not possible to speak of - geospatial data - as a single type of information that can be handled by multiple, functionally equivalent applications and formats." (McGarva et al 2009, 5). As with other data types discussed in these Guides, where the original source data cannot be archived outside of the GIS software, the most suitable files to use for archiving GIS data fall into the categories of open formats (e.g. GML and KML) and widely used standards (e.g. ESRI Shapefiles).

General considerations, as outlined in the Guide-wide section on Planning for the Creation of Digital Data include ensuring that data, where possible, is not encoded or compressed.

The ADS is able to accept most major file formats, though [ESRI] formats are preferred as this is the software which we actually used to manage and migrate GIS data sets. We can accept anything from a combination of DXF and DBF files to the following GIS formats:

  • Arc/Info export
  • Arc/Info ungen
  • ESRI Shapefile
  • Idrisi
  • GRASS
  • MIF/MID
  • NTF
  • SDTF
  • MOSS
  • VPF
  • GML
  • KML
  • ANYTHING SUPORTED BY GDAL/OGR TOOLS

Database Files

If you have external databases connected to your GIS system, for example a database containing your attribute data, then you may want to archive these as well. Details on how best to archive database data is covered in the Databases and Spreadsheets guide.

Image Files

It is NOT necessary to archive images of every single coverage in your GIS, nor is it necessary to archive images showing all of the ways you used the GIS to play with that data. Occasionally an image may have proven useful to you in a research project and, in order to document the research that you did, archiving that image might be worth more than 1,000 words of documentation. One example is an image showing lithic flakes scattered across a house floor in a pattern that you argued demonstrates lithic production was taking place on site -- that single image might be well worth including.

Further information on archiving raster images can be found in the Raster Images guide.

3.1.2 Documentation to accompany your GIS, database, or image files

Your data set -- the GIS files, database files, and image files -- will need to be accompanied by detailed documentation as described in Sections 3.2 and 3.3.

6.3.3.5 Metadata to accompany your GIS, database, or image files#

As mentioned in Section 5, tools are being developed to assist in the automatic creation of metadata records. These tools will take the form of interactive forms on the Internet, and assistance in downloading metadata information directly from existing databases. Information about these tools will appear in the ADS Guidelines for Depositors. In the meantime, though, life must go on tDAR utilises a number of interactive web forms to help users create metadata for resources they deposit. Metadata may also be created in either ASCII text format or as ASCII delimited database files. The ADS prefers metadata to be sent in these formats.

Is this too ADS specific?
Data can be accepted on 5.25 or 3.5 inch double-density or high-density floppy disks or CD-ROM, [DVD], over e-mail, or via FTP. If data are transferred via FTP we prefer to 'pull' data, so please contact the ADS in advance to make arrangements. Other file formats can be accommodated, please email the ADS for details.

In some cases, data sets may need to be compressed to assist in transferring information to the archive or out of it again. Large data sets with numerous component files are most easily handled in this way. For example, if you are using GRASS the complete directory structure associated with a location or mapset spatial database might be transferred to the ADS digital archive as a single compressed file.