Celms, A.Trevoho, I.Kolodiy, P.Pukite, V.Virkavs, M.Lidumnieks, T.2024-02-192024-02-192023-06-012023-06-01Assessment of qualitaty of quasigeoid models in Riga city / A. Celms, I. Trevoho, P. Kolodiy, V. Pukite, M. Virkavs, T. Lidumnieks // Modern Achievements of Geodesic Science and Industry. — Lviv : Lviv Politechnic Publishing House, 2023. — No II (46). — P. 47–54.https://ena.lpnu.ua/handle/ntb/61357The study of the shape and size of the globe on a global scale is crucial to understanding the challenges and impacts of climate, the life sciences, hydrology, hydrography and geology on the planet as a whole. The Earth's topography – the surface, the relief topography that characterizes two different types of regions and certain local urban areas - is varied and changes occur periodically. The practical significance is to create a homogeneous geodetic reference system and geodetic frame based on certainty and reliability. A dynamic model of the globe could solve many future problems. Determining the topographic surface of the Earth - the altitude above sea level – using precise levelling methods is laborious task. Today, satellite-based measurement methods - GNSS - are used. GNSS allows to determine ellipsoidal heights using satellite systems and the global ellipsoidal model parameters (X,Y,Z). The geoid – surface of the mean sea level will enable to derive normal height from ellipsoidal heights; Then compared with the normal heights of the geometric levelling method. The need for a geoid or quasigeoid model in the economy is important for construction, navigation, logistics, users and maintainers of geographic information systems. A high-precision geoid or quasigeoid model would make a qualitative contribution to real-time GNSS measurements. The theoretical part of the study gives an overview of the shape and modelling of the globe; technological methods for the development of geoid and quasigeoid models; characteristics of geoid and quasigeoid models. The study includes GNSS measurements on known Class 1 leveling line points - obtaining ellipsoidal height values at 8 selected points in the southern part of Riga city. The obtained measurements were processed and the data were compared with available geoid and quasi-geoid models.47-54engeoidquasigeoidheight systemsGNSS/levellingArticle© Західне геодезичне товариство, 2023© Національний університет “Львівська політехніка”, 20238528.45(474.362.2)Assessment of qualitaty of quasigeoid models in Riga city / A. Celms, I. Trevoho, P. Kolodiy, V. Pukite, M. Virkavs, T. Lidumnieks // Modern Achievements of Geodesic Science and Industry. — Lviv : Lviv Politechnic Publishing House, 2023. — No II (46). — P. 47–54.