On the Accurate Determination of the Orthometric Correction to Levelled Height Differences - A Case Study in Hong Kong

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F49777513%3A23520%2F25%3A43976758" target="_blank" >RIV/49777513:23520/25:43976758 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.mdpi.com/2673-7418/5/4/71" target="_blank" >https://www.mdpi.com/2673-7418/5/4/71</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3390/geomatics5040071" target="_blank" >10.3390/geomatics5040071</a>

Jazyk výsledku

angličtina

Název v původním jazyce

On the Accurate Determination of the Orthometric Correction to Levelled Height Differences - A Case Study in Hong Kong

Popis výsledku v původním jazyce

Orthometric heights are practically determined from levelling and gravity measurements by applying orthometric corrections to levelled height differences. Currently, Helmert’s definition of orthometric heights is mostly used, with the mean gravity computed only approximately from observed surface gravity by applying the Poincaré-Prey gravity reduction. In this study, we compute orthometric corrections by applying the state-of-the-art method that utilizes advanced numerical procedures to account for the topographic relief and 3D mass density variations, while adopting the Earth’s spherical approximation. The non-topographic contribution of masses inside the geoid is evaluated by solving geodetic boundary-values problems. We apply this numerical procedure for the first time to practically determine orthometric heights of levelling benchmarks from levelling and gravity measurements and digital terrain and rock density models. Results obtained after readjustment of newly determined orthometric heights at the levelling network covering the Hong Kong territories are compared with Helmert’s orthometric heights. Comparison reveals that errors in Helmert’s orthometric heights vary between -3.13 and 0.95 cm. Such errors are very significant when compared to accurate values of the cumulative orthometric correction between -1.88 and 0.84 cm. Moreover, large errors (up to 1 cm) occur already at levelling benchmarks at very low elevations (&lt; 100 m). These findings demonstrate that an accurate determination of orthometric heights is crucial even for regions with moderately elevated topography.

Název v anglickém jazyce

On the Accurate Determination of the Orthometric Correction to Levelled Height Differences - A Case Study in Hong Kong

Popis výsledku anglicky

Orthometric heights are practically determined from levelling and gravity measurements by applying orthometric corrections to levelled height differences. Currently, Helmert’s definition of orthometric heights is mostly used, with the mean gravity computed only approximately from observed surface gravity by applying the Poincaré-Prey gravity reduction. In this study, we compute orthometric corrections by applying the state-of-the-art method that utilizes advanced numerical procedures to account for the topographic relief and 3D mass density variations, while adopting the Earth’s spherical approximation. The non-topographic contribution of masses inside the geoid is evaluated by solving geodetic boundary-values problems. We apply this numerical procedure for the first time to practically determine orthometric heights of levelling benchmarks from levelling and gravity measurements and digital terrain and rock density models. Results obtained after readjustment of newly determined orthometric heights at the levelling network covering the Hong Kong territories are compared with Helmert’s orthometric heights. Comparison reveals that errors in Helmert’s orthometric heights vary between -3.13 and 0.95 cm. Such errors are very significant when compared to accurate values of the cumulative orthometric correction between -1.88 and 0.84 cm. Moreover, large errors (up to 1 cm) occur already at levelling benchmarks at very low elevations (&lt; 100 m). These findings demonstrate that an accurate determination of orthometric heights is crucial even for regions with moderately elevated topography.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10508 - Physical geography

Projekt

<a href="/cs/project/GA23-07031S" target="_blank" >GA23-07031S: Elipsoidické modelování planetárních gravitačních polí</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Geomatics

ISSN

2673-7418

e-ISSN

2673-7418

Svazek periodika

5

Číslo periodika v rámci svazku

4

Stát vydavatele periodika

CH - Švýcarská konfederace

Počet stran výsledku

34

Strana od-do

1-34

Kód UT WoS článku

001648287100001

EID výsledku v databázi Scopus

2-s2.0-105026386455