Jan Russnák

Comparison of Standard- and Proprietary-Based Approaches to Detailed 3D City Mapping

3D information is essential for a number of applications used daily in various domains such as facility management, including energy management, urban planning, telecommunications, and safety and security, etc. This paper is devoted to 3D modelling at the level of city districts with the campus and buildings modelling use case. Different methods and technologies commonly used in this area are first analysed and discussed. Emphasis is placed on the comparison of the standardized approach, represented by the CityGML (City Geography Markup Language), and proprietary technologies (developed by Masaryk University as a part of facility management called the Building Documentation System). This comparison is demonstrated on a sample 3D model of the Faculty of Science at Masaryk University in Brno, the Czech Republic, situated on Kotlařska Street. Both types of 3D models were developed while focusing on their benefits and limitations. The conclusions drawn from the study present a concept of 3D city mapping with an emphasis on where the use of CityGML reaches its limits and the point from which proprietary-based solutions should be implemented. Recommendations on future CityGML development are given at the end of the article. Some of our current recommendations have been incorporated into version 2.0 of the CityGML implementation specification by the Open Geospatial Consortium. Furthermore, we are participating in the ongoing development of CityGML version 3.0.

The Design and Testing of 3DmoveR: an Experimental Tool for Usability Studies of Interactive 3D Maps

Various widely available applications such as Google Earth have made interactive 3D visualizations of spatial data popular. While several studies have focused on how users perform when interacting with these with 3D visualizations, it has not been common to record their virtual movements in 3D environments or interactions with 3D maps. We therefore created and tested a new web-based research tool: a 3D Movement and Interaction Recorder (3DmoveR). Its design incorporates findings from the latest 3D visualization research, and is built upon an iterative requirements analysis. It is implemented using open web technologies such as PHP, JavaScript, and the X3DOM library. The main goal of the tool is to record camera position and orientation during a user’s movement within a virtual 3D scene, together with other aspects of their interaction. After building the tool, we performed an experiment to demonstrate its capabilities. This experiment revealed differences between laypersons and experts (cartographers) when working with interactive 3D maps. For example, experts achieved higher numbers of correct answers in some tasks, had shorter response times, followed shorter virtual trajectories, and moved through the environment more smoothly. Interaction-based clustering as well as other ways of visualizing and qualitatively analyzing user interaction were explored.

Evaluation of User Performance in Interactive and Static 3D Maps

Interactive 3D visualizations of geospatial data are currently available and popular through various applications such as Google EarthTM and others. Several studies have focused on user performance with 3D maps, but static 3D maps were mostly used as stimuli. The main objective of this paper was to identify differences between interactive and static 3D maps. We also explored the role of different tasks and inter-individual differences of map users. In the experimental study, we analyzed effectiveness, efficiency, and subjective preferences, when working with static and interactive 3D maps. The study included 76 participants and used a within-subjects design. Experimental testing was performed using our own testing tool 3DmoveR 2.0, which was based on a user logging method and open web technologies. We demonstrated statistically significant differences between interactive and static 3D maps in effectiveness, efficiency, and subjective preferences. Interactivity influenced the results mainly in ‘spatial understanding’ and ‘combined’ tasks. From the identified differences, we concluded that the results of the user studies with static 3D maps as stimuli could not be transferred to interactive 3D visualizations or virtual reality.

Flood Modelling and Visualizations of Floods through 3D Open Data

This paper is devoted to 3D modelling at the city level from data sources considered as open. The open data presented in this paper enable free usage, modifications, and sharing by anyone for any purpose. The main motivation was to verify feasibility of a 3D visualization of floods purely based on open technologies and data. The presented state-of-the-art analysis comprises the evaluation of available 3D open data sources, including formats, Web-based technologies, and software used for visualizations of 3D models. A pilot Web application visualizing floods was developed to verify the applicability of discovered data sources. 3D visualizations of terrain models, 3D buildings, flood areas, flood walls and other related information are available in a pilot application for a selected part of the city of Prague. The management of different types of input data, the design of interactive functionality including navigation aids, and actual limitations and opportunities for future development are discussed in detail at the end.

Measurement of snow cover depth using 100 × 100 meters sampling plot and Structure from Motion method in Adventdalen, Svalbard

We tried to verify the concept of Structure from Motion method for measuring the volume of snow cover in a grid of 100 × 100 m located in Adventdalen, Central Svalbard. As referencing method we utilized 121 depth measurements in one hectare area. Using avalanche probe a snow depth was measured in mentioned 121 nodes of the grid. We detected maximum snow depth of 2.05 m but snowless parts as well. From gathered depths’ data we geostatistically (ordinary kriging) interpolated snow surface model which we used to determine reference volume of snow at research plot (5 569 m3 ). As a result, we were able to calculate important metrics and analyze topography and spatial distribution of snow cover at the plot. For taking photos for Structure from Motion method, bare pole in hands with a camera mounted was used. We constructed orthomosaic of research plot.

Visualization and spatial analysis of police open data as a part of community policing in the city of Pardubice (Czech Republic)

ABSTRACT Different types of spatial analyses and visualizations can be used in the police practice for investigation, crime prediction, and planning of police forces. The public availability of crime data is one of the often discussed issues for the police, general public and academia. The efforts to open police data are rooted in the philosophy of the so-called ‘community policing’. In this article, we demonstrate the possibilities of spatial analysis and cartographic visualization of open crime data. We provide two use cases based on the data gathered by the municipal police in Pardubice, Czech Republic. We investigate the impact of gambling sites on crime offence intensity and found that gambling sites considerably influence their surroundings within 100 m. The other use case is focused on traffic offences caused by cyclists. We extracted hot spots of these offences and tried to identify their causation, since the police should not only carry out repressive measures, but also strive to eliminate the causes (e.g. add cycle lanes, bike paths, underpasses or overpasses). Different types of cartographic visualization have been designed and discussed for both use cases. The advantages, limitations and future development of the described concepts are commented on in the conclusion.