Valdez multi-resolution DEMs
Version 1.0, June 14-19, 2019
Prepared by Tom Patterson, US NPS (retired)
3.3, 7.5, 15, 30, 90, 250, 500, 1,000, and 2,000
Size (height samples)
1,500 x 1,500
Albers Equal-Area / NAD83
Standard parallel 1: 55N
Standard parallel 2: 65N
Latitude of origin: 50N
Central meridian: 146.5W
The 3.3. 7.5, and 15 meter digital elevation models (DEM) derive from USGS 3DEP LiDAR at 3.33-meter resolution. The 30, 90, and 250 meter DEMs derive from 3DEP IFSAR at 5-meter resolution. The 500m DEM derives from 2-arc second 3DEP, which includes less detailed Canadian DEMs at the same resolution, although the difference is difficult to detect after downsampling to 500-meter resolution. The 1,000 and 2,000 meter DEMs derive from 3-arc second data downloaded from , which combines USGS, Canadian government, and SRTM elevation sources.
The processing of DEMs occurred in Natural Scene Designer Pro, QGIS, and Geographic Imager software and involved converting between NSD, IMG, ASCII Grid, and TIF formats. Slight elevation variations exist, ranging up to a few decimeters, between DEMs in each of the multi-resolution series. We used bicubic interpolation for downsampling and did not apply additional filtering or generalization to the DEMs.
The ocean surface was added presumably from a different source than the terrestrial LiDAR and creates an abrupt shoreline on 3.3. 7.5, and 15 meter DEMs. On the 90m DEM, a north-south data seam is visible at the terminus of Columbia Glacier west of Valdez.
All data used to prepare the DEMs found on this site are from free sources. The DEMs that derive from USGS 3DEP, Canadian government, and SRTM data are in the public domain. The DEMs deriving from have been made available by Jonathan de Ferranti under the Creative Commons Attribution 4.0 International license.