Darwin Harbour Habitat Mapping Program: Backscatter entropy

Brief description

This resource contains a GLCM (Grey-Level Co-occurrence Matices) entropy grid of the backscatter data for the greater Darwin Harbour region as part of a baseline seabed mapping program of Darwin Harbour and Bynoe Harbour. This project was funded through offset funds provided by an INPEX-led Ichthys LNG Project to the Northern Territory Government’s Department of Environment and Natural Resources (NTG-DENR) with co-investment from Geoscience Australia (GA) and the Australian Institute of Marine Science (AIMS). The intent of this program is to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline data that enable the creation of thematic habitat maps and information to underpin marine resource management decisions. The GLCM (Grey-Level Co-occurrence Matices) entropy grid of the backscatter data was derived from a compilation of multiple surveys undertaken by GA, AIMS and NTG-DENR between 2011 and 2017, including GA0333 (Siwabessy et al., 2015), GA0341 (Siwabessy et al., 2015), GA0351/SOL6187 (Siwabessy et al., 2016), GA4452/SOL6432 (Siwabessy et al., 2017), GA0356 (Radke et al., 2017), and GA0358 and GA0359 (Radke et al., 2018), adding to those from a previous survey GA0333 collected by GA, AIMS and NTG-DENR. Entropy measures the disorder or complexity of an image. The entropy is large when the image is texturally complex.

Lineage

Maintenance and Update Frequency: asNeeded

Statement: The data was a derivative of the multibeam backscatter data. It was generated in ENVI 5.2 using the Co-occurrence Measures tool under the Filter toolbox. The Greyscale quantization level was set at 64. The Co-occurrence Shift was set at 1 for both X and Y direction. The Processing Window size was set at 3 by 3 or 7 by 7 or 15 by 15. It is acknowledged that the multibeam sonar data were collected from multiple surveys GA4425 in 2010, GA0333 in 2011, GA0351/SOL6187 in 2015, GA4452/SOL6432 in 2016, GA0361 in 2017 and GA0362 in 2017 and 2018. The first two surveys were acquired by Geoscience Australia (GA), Australian Institute of Marine Science (AIMS), Northern Territory Government’s Department of Environment and Natural Resources (NTG-DENR) and Darwin Port Authority using GA’s Kongsberg EM3002D multibeam echosounder from aboard MV Matthew Flinders and the last four surveys by GA, AIMS and NTG-DENR using GA’s Kongsberg EM2040C Dual multibeam echosounder from aboard RV Solander for the first two and using GA’s Kongsberg EM3002D from aboard MV Reelax and RV Capricornus for the last two respectively.