A Multi-scale topographic position image of Australia has been generated by combining a topographic position index and topographic ruggedness. Topographic Position Index (TPI) measures the topographic slope position of landforms. Ruggedness informs on the roughness of the surface and is calculated as the standard deviation of elevations. Both these terrain attributes are therefore scale dependent and will vary according to the size of the analysis window. Based on an algorithm developed by Lindsay et al. (2015) we have generated multi-scale topographic position model over the Australian continent using 3 second resolution (~90m) DEM derived from the Shuttle Radar Topography Mission (SRTM). The algorithm calculates topographic position scaled by the corresponding ruggedness across three spatial scales (window sizes) of 0.2-8.1 Km; 8.2-65.2 Km and 65.6-147.6 Km. The derived ternary image captures variations in topographic position across these spatial scales (blue local, green intermediate and red regional) and gives a rich representation of nested landform features that have broad application in understanding geomorphological and hydrological processes and in mapping regolith and soils over the Australian continent. Lindsay, J, B., Cockburn, J.M.H. and Russell, H.A.J. 2015. An integral image approach to performing multi-scale topographic position analysis, Geomorphology 245, 51–61.

The Topographic Position Index measures the topographic slope position of landforms by comparing the mean elevation of a specific neighbourhood area with the elevation value of a central cell. This is done for every cell or pixel in the digital elevation model (DEM) to derive the relative topographic position (e.g. upper, middle and lower landscape elements). Ruggedness informs on the roughness of the surface and is calculated as the standard deviation of elevations. Both these terrain components are used to generate a multi-scale topographic index over the Australian continent using the algorithm developed by Lindsay, J, B., Cockburn, J. M. H. and Russell, H. A. J., 2015. An integral image approach to performing multi-scale topographic position analysis, Geomorphology, 245, 51-61. Topographic position is captured across three spatial scale and display as a ternary image. The ternary image reveals a rich representation of nested landform features with broad application to geomorphological and hydrological process understanding and mapping of regolith and soils. <b>Value: </b>Broad application in understanding geomorphological and hydrological processes and in mapping regolith and soils over the Australian continent. Can be used as inputs into geospatial modelling and machine learning <b>Scope: </b>The dataset is national. The algorithm can be run on any digital elevation gridded dataset.