The Validity of Open-Source Elevations for Different Topographic Map Scales and Geomatics Applications

This paper presents an analysis of four open-source Global Digital Elevation Models (GDEMs) and compares them on two topographic profiles (nearly flat, hills regions) for mapping geomatics applications. The chief intention is to investigate if GDEMs-based heights, contour intervals, slopes, are valid all map scales mapping, which constitutes a major issue in activities. Two case studies, the Nile delta Egypt Makkah city Saudi Arabia, have been utilized represent flat moderate-topography patterns. investigated GDEMs include most-recent released models: ASTER v.3, ACE 2, SRTMGL1 NASADEM_HGT v.1 2019 2020 with spatial resolutions 1 3 arc seconds. Available accurate Ground Control Points (GCP) consist 540 stations 175 Makkah. Based available datasets study areas, it has found that accuracy over known checkpoints ranges from ±2.5 ±5.1 meters region, while varies between ±8.0 area. That indicates utilization differs significantly hilly regions. Therefore, recommended avoid using developing maps scale 1:25,000 or larger regions 1:50,000 Additionally, accomplished results showed GDEM-based slopes do not match actual GCP cross section’s length up 30 kilometers. Thus, concluded appropriate heights’ source at medium large scales, could be profiling precise engineering