Download Information

Users of the Antarctic Digital Database can download data in a variety of formats. Formats that are presently supported or which will be supported as soon as the server software supports them are: ESRI ARC/INFO Export files (E00), ESRI Shape-files, Well Known Text (WKT), GML, GoogleEarth KML, and ESRI "Generate" format. In addition, several image file formats are available, including GIF, JPEG and PNG. Simple Vector Format (SVF) is available, but not recommended. The most widely useful and best supported is the GML format.

ESRI Arc/Info Export format (E00)

This is the format in which the ADD has been available in past versions, and can readily be used in all versions of ESRI software. It must be converted to ARC/INFO coverages using the "IMPORT" command (or equivalent in the ArcToobox), and provides full topological structuring.

Unlike all other downloads, the data downloaded using this option does not derive from the database underlying the web services, but from pre-created files that are subdivided geographically according to IMW 1:1000,000 map tiles. However, the system will automatically select the appropriate map-tiles using the geographic coordinates entered; there is no longer any need to carry out multiple downloads for each tile.

The data will be downloaded as a single ZIP archive containing multiple directories; each directory is for a single map tile and contains all the requested data layers. Note that file names repeat between tiles. Note also that not every tile directory will contain an export file for every layer requested; there is no export file for tiles with no data in that layer (for example, tile SV31_40 has no rock outcrop).

Finally, note that this option has the potential to create extremely large downloads, up to over 100 Mbytes.

GML

GML is provided directly from the Web Feature server as GML 2. This can be imported directly into many GIS packages, and can be translated to a wide variety of other formats using the open-source program ogr2ogr. On a Windows PC, ogr2ogr can best be downloaded as part of the FWTools toolkit.

Generic Mapping Tools (GMT)

The data are provided in the format required by the psxy program. Additional information (attributes etc.) is available in comment lines according to the Draft Specification for GMT Vector Data Format For OGR Compatibility, version 0.2 by Brent Wood.

Users should note that "holes" in polygons cannot normally be handled by psxy. However, the data provided handles nested polygons as follows:

• The outer perimeter of a polygon is indicated by a comment line "# @P"
• A hole within the outer perimeter is indicated by a comment line "# @H"

All additional information in the file is handled as comment lines, and so should be backward compatible.

ESRI "Generate" Format

ESRI "Generate" format provides a simple, text representation of the geometry of the data. Each file contains only a single geometry type. The formats are:

Lines

The file consists of a series of sections which start with a numeric ID on a line by itself, followed by 2 or more lines with X,Y coordinate pairs, finishing with the word "END" on a line by itself. This pattern may repeat as many times as necessary. The end of the file is indicated by the word "END" on a line by itself immediately after the "END" of a line section.

Points

The file consists of one or more lines, each of which has an ID number followed by a pair of coordinates. The file ends with the word "END" on a line by itself.

Polygons

The file consists of a series of sections which start with a numeric ID on a line by itself, followed by 3 or more lines with X,Y coordinate pairs, finishing with the word "END" on a line by itself. The last point specified is joined to the first point by a straight line. This pattern may repeat as many times as necessary. The end of the file is indicated by the word "END"on a line by itself immediately after the "END" of a polygon section. N.B. This technique CANNOT represent island polygons, and only the outer ring of each polygon will be given. Nested polygons will therefore appear as overlapping polygons, and must be processed further in whatever GIS package is used to obtain correct topology.

"Generate" formatted data will be provided as a ZIP archive containing two files for each layer selected. One (with the name <layer>.gen) contains the "Generate" geometric information; the other (with the name <layer>.csv) contains a comma separated representation of the attribute data. Records in the two files can be joined using the ID number..

GoogleEarth KML

Google Earth uses a file format known as KML.

KML data will be provided as a ZIP archive containing one KML file for each layer downloaded, and an additional KML file containing all the layers selected.

NOTE! If you use data from the ADD as part of other web-sites, you MUST acknowledge the source of the data

Image file formats (GIF, JPG and PNG)

Image data will be provided as a ZIP archive containing one file for each layer downloaded, and an additional file containing all the layers selected. The image background is set to transparent if the format supports transparency

The download software will compute the dimensions of the image based on the scale of the download data and the extent of the area selected. It will never produce an image less than 500 pixels in its larger dimension. There is the potential for very large images to be generated if large scale data are selected with too large an area of interest

Image files are generated projected in the WGS 84 / Antarctic Polar Stereographic (EPSG:3031) projection. This is a Polar Stereographic projection centred on the South Pole, with a Latitude of True Scale at 71°S. The datum is WGS 84.

NOTE! If you use data from the ADD as part of other web-sites, you MUST acknowledge the source of the data

ESRI Shape-files

The Shape-file format is a format created and owned by ESRI, but which ESRI have made publicly available. It is documented on ESRI's web-site.

The data will be downloaded as a Zip archive containing several files; these should all be placed in the same directory.

Simple Vector Graphic format (SVG)

SVG data will be provided as a ZIP archive containing one file for each layer downloaded, and an additional file containing all the layers selected.

SVG files are generated projected in the WGS 84 / Antarctic Polar Stereographic (EPSG:3031) projection. This is a Polar Stereographic projection centred on the South Pole, with a Latitude of True Scale at 71°S. The datum is WGS 84.

NOTE! If you use data from the ADD as part of other web-sites, you MUST acknowledge the source of the data

WKT Format

WKT provides a simple, text representation of the geometry of the data. The formats are:

• POINT(0 0)
• LINESTRING(0 0,1 1,1 2)
• POLYGON((0 0,4 0,4 4,0 4,0 0),(1 1, 2 1, 2 2, 1 2,1 1))
• MULTIPOINT(0 0,1 2)
• MULTILINESTRING((0 0,1 1,1 2),(2 3,3 2,5 4))
• MULTIPOLYGON(((0 0,4 0,4 4,0 4,0 0),(1 1,2 1,2 2,1 2,1 1)), ((-1 -1,-1 -2,-2 -2,-2 -1,-1 -1)))
• GEOMETRYCOLLECTION(POINT(2 3),LINESTRING((2 3,3 4)))

Only Point, LineString, Polygon and MultiLineString are likely to be returned from the ADD.

WKT formatted data will be provided as a ZIP archive containing two files for each layer selected. One (with the name <layer>.wkt) contains the well known text; the other (with the name <layer>.csv) contains a comma separated representation of the attribute data. Records in the two files correspond one to one.

The Antarctic Digital Database is copyright © the Scientific Committtee on Antarctic Research 1993 - 2006.

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