The Validity of Open-Source Elevations for Different Topographic Map Scales and Geomatics Applications in Egypt and Saudi Arabia| Chapter 1 | Novel Perspectives of Geography, Environment and Earth Sciences Vol. 2

 The likeness of the Earth’ terrain in a 3D mathematical layout is a lively constituent in a expansive range of geographic, geomatics, incidental, and construction ventures. However, the veracity of aforementioned likenesses commit delineate allure relevance and validity for a particular exercise. This division presents an reasoning of four open-beginning Global Digital Elevation Models (GDEMs) and compares ruling class on two topographic sketches (almost flat, and highlands domains) for mapping and geomatics uses in two nations. The main aim search out decide either GDEMs-located altitude, outline breaks, slopes, and topographic sketches are accurate for all map of earth features scales, that is a meaningful question in plan movements. For the purpose of illustrating flat and moderate-terrain patterns, two case studies—the Nile arm of the sea in Egypt and Makkah city in Saudi Arabia—have happened secondhand. The investigated GDEMs involve ultimate-current freed models: ASTER v.3, ACE 2, SRTMGL1 v. 3, and NASADEM_HGT v.1 freed in 2019 and 2020 accompanying dimensional judgments of 1 and 3 curve seconds. There are 540 correct Ground Control Points (GCP) available in the Nile arm of the sea and 175 in Makkah.It has existed driven established the accessible datasets in two study sites that  the veracity of examined GDEMs over popular checkpoints range from ±2.5 and ±5.1 meters in the Nile arm of the sea domain, while it varies 'tween ±5.1 and ±8.0 meters in the Makkah region. This implies that the use of GDEMs in topographic plan changes considerably betwixt relating to space regions that are flat and those that are sloping. Therefore, it is advised against exploiting GDEMs to generate topographic maps at scales of 1: 25,000 or better in flat fields and 1: 50,000 or better in steep fields. Additionally, the worked out results manifested that during the whole of cross portions up to 30 kilometers in distance, no GDEM-located slope equals the evident slopes from popular GCP. This leads to the judgment that GDEMs are not the appropriate climax' beginning for topographic plan at medium and abundant map scales, and commit not be exploited for topographic create a likeness in a picture in exact manufacturing and geomatics requests. Such verdicts endure be intensely captured into account in plan and architecture requests not just in Egypt and Saudi Arabia but general also.

Author(s) Details:

Gomaa M. Dawod,
Survey Research Institute, National Water Research Center, Giza, Egypt.

Ibrahim E. Ascoura,
Umm Al-Qura Univerity, Makkah, Saudi Arabia.

Please see the link here: https://stm.bookpi.org/NPGEES-V2/article/view/9276