Interpolated SRTM V3 compared to US SRTM (N45W111)

After all DEM input data set were interpolated to the consistent resolution of 1 arcsecond, overlapping regions were mathematically analyzed and compared to determine the output product’s quality. The interpolated SRTM V3 DEM overlaps with the high resolution US SRTM in the United States. As shown on the right, the two DEMs differ very little. As expected the US SRTM is slightly more detailed compared to SRTM V3, which had an original resolution of 3 arc seconds.

SRTM V3 Interpolated from 3 to 1 arc-second

US SRTM 1 arc-second

Interpolated SRTM V3 compared to US SRTM (N45W111)

Cross-Section at 45.6861 ° N

This profile plot shows elevation variations along a cross-section of both DEMs. The plot demonstrates the effectiveness of interpolation; the interpolated SRTM V3 closely matches the level of detail in US SRTM.

Interpolated GTOPO30 compared to Interpolated SRTM V3 (N45W121)

Cross-Section at 45.7222 ° N		GTOPO30 Interpolated from 30 to 1 arc-second		SRTM Interpolated from 3 to 1 arc-second
		The relative lack of detail present in GTOPO30 is expected since the input DEM was interpolated from 30 to 1 arcsecond. Compared to SRTM V3, GTOPO30 is very coarse indicating that its interpolation was only useful in establishing a consistent global resolution of 1 arcsecond. Despite its relative low quality, GTOPO30 serves as a useful supplementary DEM in regions not covered by higher quality DEMs.

Interpolated Alaska DEM compared to SRTM V3 (N55W160)

The comparison of the interpolated Alaska DEM to SRTM V3 demonstrate the slightly better quality of the Alaska DEM. Not only is the Alsaka DEM more detailed, but it also serves as supplement to SRTM’s missing data north of 60°. Cross-Section at 55.9722 ° N		Alaska DEM Interpolated from 2 to 1 arc-second
		SRTM Interpolated from 3 to 1 arc-second

Interpolated Canada DEM compared to SRTM V3 (N56W120)

The interpolation of the Canada DEM, which was originally had a resolution of 3 x 6 arc second, allowed for a consistent resolution along both longitude and latitude. Interpolation was effective as shown by the comparisons; the interpolated Canada DEM closely matches the level of detail in the interpolated SRTM V3 DEM. Cross-Section at 55.9722 ° N		Canada DEM Interpolated from 2 to 1 arc-second
		SRTM Interpolated from 3 to 1 arc-second

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