Critical Aeronautical Heights for Australia, 30 deg. by 30 deg., Australian Survey and Land Information Group (AUSLIG)

The M7 data represent the highest points in each 30 minute by 30 minute grid square for Australia. see: 'ga.gov.au/' The following text was abstracted from Bruce Gittings' Digital Elevation Data Catalogue: 'geo.ed.ac.uk/home/ded.html'. The catalogue is a comprehensive source of information on digital elevation data and should be retrieved in its entirety for additional information. Australian Data is available from the Australian Survey and Land Information Group (AUSLIG).

There are three products; M7 are Critical Aeronautical Heights which represent the highest point in each 30'x30' quad, M8 are Spot heights (ie. an irregular grid) and M9 represents an 18" (~500m) grid at 1:250,000 scale (gridded from M8 using an Hutchinson Algorithm). Both M8 and M9 have incomplete coverage of the country. The 500m grid covers 30% of Australia (Southern New South Wales, Victoria, parts of Northern Queensland and selected cities).