Relief - Elevation Range over 1000 m derived from 1" SRTM DEM-S

The elevation range measures the full range of elevations within a circular window and can be used as a representation of local relief. \n\nThe 1000 m elevation range product was derived from the Smoothed Digital Elevation Model (DEM-S; ANZCW0703014016), which was derived from the 1 arc-second resolution SRTM data acquired by NASA in February 2000. \n\nThis collection includes Relief data at 1 arc-second and 3 arc-second resolutions.\n\nThe 3 arc-second resolution product was generated from the 1 arc-second 1000 m elevation range product and masked by the 3” water and ocean mask datasets.\nLineage: Source data\n1.\t1 arc-second SRTM-derived Smoothed Digital Elevation Model (DEM-S; ANZCW0703014016).\n2.\t1 arc-second 1000 m elevation range product\n3.\t3 arc-second resolution SRTM water body and ocean mask datasets\n\n1000 m focal range elevation calculation\nElevation range is the full range of elevation within a circular window (Gallant and Wilson, 2000). Focal range using a 1000 m window was calculated for each grid point from DEM-S using a 1000 m kernel. The different spacing in the E-W and N-S directions due to the geographic projection of the data was accounted for by using the actual spacing in metres of the grid points, and recalculating the grid points included within the kernel extent for each 1o change in latitude.\n\nThe 1000 m focal range elevation calculation was performed on 1° x 1° tiles, with overlaps to ensure correct values at tile edges.\n\nThe 3 arc-second resolution version was generated from the 1 arc-second 1000 m elevation range product. This was done by aggregating the 1” data over a 3 x 3 grid cell window and taking the maximum of the nine values that contributed to each 3” output grid cell. The 3” 1000 m elevation range data were then masked using the SRTM 3” ocean and water body datasets.\n\n\nReferences\nGallant, J.C. and Wilson, J.P. (2000) Primary topographic attributes, chapter 3 in Wilson, J.P. and Gallant, J.C. Terrain Analysis: Principles and Applications, John Wiley and Sons, New York.