Damir Medak

Lifestyles - An Algebraic Approach to Change in Identity

This paper proposes a unified formal environment for spatiotemporal databases and modeling the change in identity of objects. The real world is represented as a set of snapshots consisting of identifiable objects and relations among objects. A database needs transaction time for the consistent management of temporal links among identifiers. Four basic operations affecting object identity are proposed: create, destroy, suspend, and resume. Their compositions are either applicable on a single object (evolve), or on a group of objects (constructive and weak fusion, fission, aggregate and segregate). These operations build a finite set of identity affecting operations - lifestyles. Executable algebraic specifications, written in the functional programming language Haskell, are provided both for the database model and for lifestyles. The specifications of typical lifestyles can be re-used for various application domains.

PROCESSING OF GEODYNAMIC GPS NETWORKS IN CROATIA WITH GAMIT SOFTWARE

This paper presents geodetic results for the area around the city of Zagreb. After three series of GPS measurements, the analysis of the first results with scientific software GAMIT show significant geodynamic activity in the research area. Horizontal velocities of several millimeters per year were obtained, whereas the error budget of GPS observations was smaller by an order of magnitude. Comparison of geodetic results with geologic research show that the motions at the surface and under the ground have opposite directions. The velocity magnitudes are compatible with recent seismic activity in the Medvednica area. In order to get more reliable results, new measurements have been planned.

Gravity Field Determination in Croatia — Status Report

The first serious works on the determination of the Earth’s gravity field in Croatia began at the Faculty of Geodesy, University of Zagreb, nearly twenty years ago and they have been extremely intensified in the last few years. Detailed review of all efforts and preparations can be found in (Colic et al., 1993a). This poster presents the short survey of those investigations with the most interesting achievements. The final results for Croatian gravity field parameters, including the combination of different kinds of data - gravity anomalies, vertical deflections, satellite altimetry, topography, ... - are planned to be made public in the year 1995.

Comparison of interpolation methods and image correlation in the collection of data for digital elevation model

Digital Relief Model (DRM) is the name used officially in Croatia, and we distinguish between the original and derived DRM. Referring to the regular raster structure of elevations stored in the derived DRM, the term digital elevation model (DEM) was used for this model. Three geomorphometrically different landscapes have been tested. The elevation points were created using two methods, interpolation from the data obtained in the photogrammetric survey and image correlation, in two resolutions (5x5 and 25x25 meters). The paper presents the differences in the application of two methods of calculating DEM. The causes of differences discussed and the relative estimation of the accuracy of each method elaborated by comparing the height of points on new models with the heights on original DRM. The recommendation for the usage of the acceptable method is given related to the accuracy, the speed of data collection and a higher degree of automation.

Influence of pit removal algorithms on surface runoff simulation

Preduvjet za hidroloske analize je digitalni model reljefa (DMR) s uklonjenim depresijama. U radu su istražena su dva algoritma za uklanjanje depresija, metoda prokopavanja i metoda popunjavanja na tri geomorfometrijski razlicita podrucja. Ulazni podaci su digitalni modeli visina (DMV) nastali interpolacijom iz podataka fotogrametrijske izmjere u prostornoj rezoluciji 5 x 5 metara. Na osnovi geomorfometrijskih i statistickih analiza dana je preporuka za uporabu prihvatljivije metode kreiranja DMV-a bez depresija uz minimalne geomorfometrijske promjene, cime je dokazana važnost odabira ispravnog algoritma.

Geospatial monitoring of green infrastructure – case study Zagreb, Croatia

This paper presents current research done under the GEMINI (Geospatial monitoring of green infrastructure using terrestrial, airborne and satellite imagery) project. GEMINI is a scientific project of the Faculty of Geodesy, University of Zagreb and Croatian Forest Research Institute funded by the Croatian science foundation. The project aims to explore new knowledge about the green infrastructure (GI) monitoring. The study area of the research is the capital of Croatia, the city of Zagreb. One of the main goals of the project is to explore the possibilities of data integration of all available remote sensing platforms: satellite, aerial and UAV (Unmanned Aerial Vehicles) imagery, terrestrial imagery and ground truth data. UAV-based remote sensing offers great possibilities to acquire field data for monitoring of GI within the urban areas in a fast and easy way. The main objective of this research is to establish an innovative, multidimensional system for monitoring of urban green infrastructure. It will integrate the latest means of data collection (multispectral satellite imagery improved and calibrated with high resolution terrestrial and airborne multispectral sources), advanced spatial analysis with the aim to improve decision support system for better management of urban GI. This project will improve the current state of the inventory and monitoring of the urban GI to support decision making and preservation of GI benefits, through the establishment of comprehensive procedures for integration of different sources of imagery at different resolution scales: satellite, terrestrial and airborne. This research will focus on novel methods for GI monitoring on the integration of different multispectral imagery sensors. It will require a highly multidisciplinary approach, leading to improvements in methods and procedures for automatic and semi-automatic processing of a large number of geospatial imagery data in the field of urban forest management with expected impact in forestry, arboriculture, urban and geospatial science.

Comparing Various Solutions for the Mohorovičić Discontinuity Shape in the Dinaric-Pannonian Region

Strong linear relationships between gravity anomalies, absolute geoid undulations, topographic heights and Mohorovicic discontinuity depths have been detected on the Dinaric—Pannonian territory almost a decade ago. The prediction of Moho depths using the existing seismic data and these relationships has been gradually improved. This paper enlightens the present state of the art.