Macquarie Island AIRSAR DEM (Digital Elevation Model)

Full description

A digital elevation Model (DEM) of Macquarie Island with a five metre grid interval, and held in UTM Zone 57 , WGS 84 coordinates. Heights are referenced to mean sea level. 5 metre contours to the 5 metre level were derived.

This metadata record is related to the metadata record Macquarie Island and adjacent islands 1:50000 Coastline GIS Dataset.

The DEM was improved by Dr Michael Roach, Lecturer in Geophysics, School of Earth Sciences - CODES, University of Tasmania, Hobart, Tasmania, Australia and a copy provided to the Australian Antarctic Data Centre in January 2006. This improved version is the dataset available for download.

Details about the processing done by Dr Roach are available from the link below.

Lineage

Progress Code: completed

Statement: The Australian Antarctic Division (AAD) DEM is based on a DEM produced by Horizon Geoscience Consulting Pty Ltd (HGC) from AIRBORNE Synthetic Aperture Radar images acquired on August 16, 2000 by NASA PACRIM Mission 2. Heights in the AAD DEM were referenced to Mean Sea Level. The HGC DEM was processed as follows: 1. AAD AIRSAR Mosaic - processed TOPSAR DEM and C-band VV-data files from mosaic of AIRSAR scenes TS1197 and TS1188. Data were acquired on 16th August 2000. DEM data from each scene were mosaicked to minimize the loss of data from the effect of radar shadow. C-band VV-polarization brightness data are also mosaicked because the phase information used to generate the DEM are acquired from the C-band VV-polarization signals. 2. AAD SPOT - processed images from SPOT PAN/MSS scene recorded on 22nd December 1994 and supplied by AAD. 3. AAD TS1188 - processed images from AIRSAR flightline Macquarie 13-1 acquired on 16th August 2000. Data were acquired in a south-to-north direction with the AIRSAR antenna sytem looking west towards the island. Therefore can expect east-facing steep slopes preferentially oriented towards the incident signals to be very bright and often saturated while west-facing slopes may be in radar shadow with no signal available. 4. AAD TS1197 - processed images from AIRSAR flightline Macquarie 193-1 acquired on 16th August 2000. Data were acquired in a north-to-south direction with the AIRSAR antenna sytem looking east towards the island. Therefore can expect west-facing steep slopes preferentially oriented towards the incident signals to be very bright and often saturated while east-facing slopes may be in radar shadow with no signal available. 5. ArcView Contour Files - contour files ready for displaying in an Arc environment. Contours have been generated for 5 metre intervals for a height range of 5 to 410 metres. Refer to the metadata record 'Macquarie Island contour data derived from Airborne Synthetic Aperture Radar images captured August 2000' for a link to download the contour data. Processing of the AIRSAR data. 1. Radiometric corrections - each strip had the following processing sequence applied: a. Masking to remove null values including out-of-range Finite values, Non-Numbers and Infinite Values. b. Antenna pattern correction to normalize the intensity across the swath from near to far range. c. Adaptive filtering to suppress speckle and electronic noise in the data. 2. Geometric corrections: a. Radiometrically-corrected data were rotated to be aligned to the direction of acquistion - ie 13 and 193 degrees. b. Using the locator information collected during the acquisition phase by on-board precision navigational systems including INS and EGI instruments, the data were further rotated, scaled and transformed using a 1st order polynomial fit to a Universal Transverse Mercator projection (Zone 57 South) and WGS 1984 Horizontal Datum. Comparison of the processed data with the geolocated SPOT imagery (rescaled to 5 metre pixel resolution) demonstrated a 1-to-1 correlation. The DEM is for Macquarie Island only and does not include Judge and Clerk or Bishop and Clerk islands. Usually mapped to a Universal transverse Mercator projection, zone 57, units metres, spheroid GRS80, Datum WGS84.