Half Moon Lake regolith-landform map and GIS datasets

Brief description

Arcview GIS containing a regolith-landfrom map with associated site database. Most sites have a field photograph hot linked into the GIS. Complementary datasets include, digital elevation model and enhanced Landsat TM imagery.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: Regolith-landform polygons were compiled from airphotos, satellite and geophysical imagery. The airphotos were principally used to map the landforms. Compositional information within these landform units was then interpreted from gamma-ray and enhanced Landsat TM imagery at the same scale as the aerial photographs. The compilation sheet at 1:80 000 scale was scanned, cleaned and attributed using ArcInfo GIS software. Site data was entered in Geoscience Australia's regolith database (RTMAP) database and then extracted to make a point attribute file in ArcInfo. The regolith characteristics of over 120 sites were recorded, and referenced using a Garmin GPS with a +/- 70 m location accuracy. Image datasets were all enhanced in ERmapper:- Landsat TM: The Landsat TM image was derived from path and row 101/81 and was enhanced to highlight regolith materials by a technique called Directed Principal Component Analysis (DPCA). For more information on this technique, see the 'more metadata' section. The result is an image which displays the clay derived band as red, iron oxide in green and silica in blue (see report for more detailed descriptions). Atmospheric backscatter particularly in the shorter wavelengths, higher frequency bands (eg. 1, 2, 3 and 4) was removed using a technique called "dark pixel subtraction". See the 'more metadata' for more information on this technique. Digital elevation model (DEM) The DEM was compiled by AUSLIG, AGSO, the Australian Heritage Commission and the Australian National University. It has a grid spacing of 9 second (in longitude and latitude) that equates to a 250m grid size.