Improving the Quality of Height Data Transformation
About the project
Project title: Improving the Quality of Height Data Transformation
Acronym: HRTrans
Type and funding: institutional research project, funded from resources of the National Recovery and Resilience Plan 2021-2026.
(Source 581 Recovery and Resilience Facility).
Implementation period: 1 October 2025 - 30 September 2029
Project Manager: Ivan Razumović
The introduction of new national reference coordinate systems creates the need to ensure continuity in the use of spatial data. The Croatian height transformation model HTMV is the basic and official infrastructure for the transformation of height data between the old HVRS1875 and the new HVRS71 height reference system of the Republic of Croatia. The Croatian height transformation model is integrated into the T7D, the official software for the unified transformation of positional and height coordinates of points in the territory of the Republic of Croatia, whose official use has been prescribed by the State Geodetic Administration of the Republic of Croatia. HTMV was realized as a grid transformation model based on separate modelling of datum and distortion components of height differences. The main objective of the project an independent analysis of external accuracy of the Croatian height transformation model in the territory of the Republic of Croatia and improvement of quality of the existing transformation model by implementing the concept of hierarchical decomposition of a homogeneous transformation grid into sub-grids with smaller cell sizes for particular local areas covered by the model that are adapted to the number and positional distribution of benchmarks in the area where they are located. The focus is on larger towns along the coast of the Republic of Croatia (Pula, Rijeka, Split, Dubrovnik), but also in the interior (Osijek) where there are larger city levelling networks with a large and adequately homogeneous benchmark field, for which areas an independent analysis of the quality of the HTMV does not exist.
Research team
Ivan Razumović – Project Manager.
Ivan Razumović is an associate professor at the Chair of Analysis and Processing of Geodetic Measurements of the University of Zagreb Faculty of Geodesy. He received his PhD in 2014 with a dissertation entitled The analysis of high accuracy transformation as a basis for the transformation of height reference systems. The areas of his scientific research are largely related to the reference coordinate systems, transformation models and the coordinate transformation of high accuracy. He actively participated in the realization of several scientific and scientific-professional projects related to height reference systems and the transformation of height data.
Ivka Kljajić
Ivka Kljajić is an associate professor at the Chair of Geoinformation of the University of Zagreb Faculty of Geodesy. The areas of her scientific research are digital cartography and geoinformation systems, visualization of spatial data and analysis of cartographic representations from different periods. She actively participated in the realization of several scientific and scientific-professional projects.
Blaženka Bukač
Blaženka Bukač is a senior assistant at the Chair of Analysis and Processing of Geodetic Measurements of the University of Zagreb Faculty of Geodesy. Her scientific interest is primarily related to the height component of reference systems, computational data processing and the quality of geo-data. She received her PhD in 2025 with a dissertation dealing with the realization and analyses of the relationship between Croatian and European vertical reference systems and the creation of the corresponding transformation models.
Ivan Ljubičić
Ivan Ljubičić has been an assistant at the Chair of Land Surveying of the University of Zagreb Faculty of Geodesy since 2022. His activities in the implementation of the project are primarily related to the collection, preparation and analysis of available benchmark data and their transformation from the analogue to digital form.