A digital elevation Model (DEM) of the Bunger Hills with a five metre grid interval,and held in UTM Zone 47, WGS 84 horizontal coordinates and EGM 96 elevation datum. Heights are referenced to Ellipsoid EGM96. The DEM was produced by SPOT image and conforms to standard SPOT image specifications.
See PDF document SPOT DEM Product Description Version 1.2 January 1, 2005. ... SPOT DEM accuracies.
The DEM accuracy specifications below are valid for a full square degree and solely apply to DEMs generated from HRS imagery and not to DEMs derived from external sources. The SPOT DEM absolute horizontal and vertical accuracies depend on the dimensions of the area of interest or on the availability of Reference3D on this area:
Absolute planimetric accuracy:
Circular error with respect to WGS84 (confidence level 90%) 15m to 30m
Absolute elevation accuracy:
Linear error with respect to EGM96 (confidence level 90%)
flat or rolling terrain (slope - 20%) 10m to 20m
SPOT DEM products may have variable planimetric and elevation performances: Small areas: One to a few HRS stereopairs HRS intrinsic accuracies 30m @90% planimetric accuracies 20m@90% elevation accuracy
The absolute planimetric accuracy of 15m can be achieved if excellent-quality ground control points (better than 10m) are used.
NOTE: No ground control points were used in the DEM.
DEM layer corrections
SPOT DEM production systematically includes:
Automatic filtering to eliminate correlation artifacts Flattening of non-running water bodies (rivers etc excluded) exceeding 0.5km2