Mar 5th, 2014 by Günther Sagl
Identifying and characterizing variations of human activity – specifically changes in intensity and similarity – in urban environments provide insights into the social component of those eminently complex systems. Using large volumes of user-generated mobile phone data, we derive mobile communication profiles that we use as a proxy for the collective human activity. In this paper, geocomputational methods and geovisual analytics such as Self-Organizing Maps SOM are used to explore the variations of these profiles, and its implications for collective human activity. We evaluate the merits of SOM as a cross-dimensional clustering technique and derived temporal trajectories of variations within the mobile communication profiles. The trajectories’ characteristics such as length are discussed, suggesting spatial variations in intensity and similarity in collective human activity. Trajectories are linked back to the geographic space to map the spatial and temporal variation of trajectory characteristics. Different trajectory lengths suggest that mobile phone activity is correlated with the spatial configuration of the city, and so at different times of the day. Our approach contributes to the understanding of the space-time social dynamics within urban environments.
- 3D visualization of mobile phone activity
Sagl, G., Delmelle, E., and Delmelle, E. (2014) Mapping collective human activity in an urban environment based on mobile phone data. Cartography and Geographic Information Science, pp. 1-14.
Mar 3rd, 2014 by Bernhard Höfle
Watch the video: http://youtu.be/TaCUaG5XEas
We use methods like laser scanning and GIS in combination with computer science to simulate the sun’s path and the respective shadows that are cast by 3D objects. Thereby, we can assess the solar potential for certain areas and surfaces. Solar potential assessments can play a crucial role in studies that have a connection to solar irradiation. The case studies presented in the video include an examination of highway noise barriers concerning their suitability for producing energy via solar panels, and the estimation of real estate value when taking into account solar income at a real estate object. Through the ability to use 3D models for shadow analyses, studies using 3D geodata are of higher quality than common 2D shadow simulations since even shadows of non-solid obstacles like vegetation can be calculated. Methods dealing with 3D geodata will become more important in the future especially for countries that try to shift to renewable energy supply and therefore need accurate evaluations of solar potential.
- Helbich, M., Jochem, A., Mücke, W. & Höfle, B. (2013): Boosting the Predictive Accuracy of Urban Hedonic House Price Models Through Airborne Laser Scanning. Computers, Environment and Urban Systems. Vol. 39(0), pp. 81-92.
- Höfle, B. & Jochem, A. (2012): 3D Laser Scanning Point Clouds and GIS - Current Developments. gis.SCIENCE. Vol. 25(2), pp. 91-100.
- Jochem, A., Höfle, B. & Rutzinger, M. (2011): Extraction of Vertical Walls from Mobile Laser Scanning Data for Solar Potential Assessment. Remote Sensing. Vol. 3(4), pp. 650-667.
- Jochem, A., Höfle, B., Rutzinger, M. & Pfeifer, N. (2009): Automatic roof plane detection and analysis in airborne LIDAR point clouds for solar potential assessment. Sensors. Vol. 9(7), pp. 5241-5262. MDPI Publishing
Mar 3rd, 2014 by Bernhard Höfle
OpenStreetMap (OSM) currently represents the most popular project of Volunteered Geographic Information (VGI): geodata are collected by common people and made available for public use. Airborne Laser Scanning (ALS) enables the acquisition of high-resolution digital elevation models that are used for many applications.
Our new study combines the advantages of both ALS and OSM, offering a promising new approach that enhances data quality and allows change detection: the mainly up-to-date 2D data of OSM can be combined with the high-resolution – but rarely updated – elevation information provided by ALS.This case study investigates building objects of OSM and ALS data of the city of Bregenz, Austria. Data quality of OSM is discerned by the comparison of building footprints using different true positive definitions (e.g. overlapping area). High quality of OSM data is revealed, yet also limitations of each method with respect to heterogeneous regions and building outlines are identified. For the first time, an up-to-date Digital Surface Model (DSM) combining 2D OSM and ALS data is achieved. A multitude of applications such as flood simulations and solar potential assessments can directly benefit from this data combination, since their value and reliability strongly depend on an up-to-date DSM.
Reference: Klonner, C., Barron, C., Neis, P. & Höfle, B. (accepted): Updating digital elevation models via change detection and fusion of human and remote sensor data in urban environments. International Journal of Digital Earth. DOI: 10.1080/17538947.2014.881427.
OpenStreetmap for young pupils
We organize a practical workshop for children between the age of 9 and 12 years within the “kids university” at Heidelberg University.
The workshop will be on Saturaday 15.03.2014 at the department of Geography and the title is “Navigieren mit der offenen Weltkarte – OpenStreetMap“. It provides an introduction to Crowdsoucing and Citizen Science in general and includes practical mapping activites for OpenStreetMap. Let’s map your world!
Further info on OSM projects for schools can be found here.
cc-asa OpenStreetMap Wiki http://wiki.openstreetmap.org/w/images/e/ea/Einweisung.jpg
Natural disasters like floods are a worldwide phenomenon and a serious threat to mankind. Flood simulations are applications of disaster control, which are used for the development of appropriate flood protection. Adequate simulations require not only the geometry but also the roughness of the Earth’s surface, as well as the roughness of the objects hereon. Usually, the floodplain roughness is based on land use/land cover maps derived from orthophotos. This study analyses the applicability of roughness map derivation approaches for flood simulations based on different datasets: orthophotos, LiDAR data, official land use data, OpenStreetMap data and CORINE Land Cover data. Object-based image analysis is applied to orthophotos and LiDAR raster data in order to generate land cover maps, which enable a roughness parameterization. The vertical vegetation structure within the LiDAR point cloud is used to derive an additional floodplain roughness map. Further roughness maps are derived from official land use data, OpenStreetMap and CORINE Land Cover datasets. Six different flood simulations are applied based on one elevation data but with the different roughness maps. The results of the hydrodynamic–numerical models include information on flow velocity and water depth from which the additional attribute flood intensity is calculated of. The results based on roughness maps derived from LiDAR data and OpenStreetMap data are comparable, whereas the results of the other datasets differ significantly.
Dorn, H., Vetter, M. & Höfle, B. (2014): GIS-Based Roughness Derivation for Flood Simulations: A Comparison of Orthophotos, LiDAR and Crowdsourced Geodata. Remote Sensing. Vol. 6(2), pp. 1739-1759. DOI:10.3390/rs6021739
We offer a new position in a new DFG project. More Info here.
Prof. Dr. Alexander Brenning from the University of Waterloo (Canada) is spending a research stay as Visiting Professor from February to August 2014 at the GIScience Research Group at Heidelberg University. This was made possible through a grant from the prestigious Humbold-Foundation. His research will focus on “Statistical GeoComputation: Linking Physical and Human Geographical Approaches“. Prof. Brenning is currently Assoc. Professor in Geomatics at the Department of Geography and Environmental Management, University of Waterloo, Ontario, Canada and has a track record in Geocomputation. Within his research stay he is particularily interested in spatial prediction modeling and spatial pattern and trend detection. These are important tasks in a data-rich world in a variety of areas including quantitative geography, environmental science, and econometrics. This fits nicely into our PhD graduate school (RTG) “CrowdAnalyser: Spatio-temporal Analysis of User-generated Content” and we are looking forward to fruitful exchange and discussions. Welcome to Heidelberg, Alexander and have a nice stay at the oldest university in Germany!
A new German Society for supporting “Citizen Science” has been founded in Heidelberg: “Verein zur Förderung von Bürgerwissenschaft e.V.”. Among the founding members are several persons with links to the Department of Geography or the GIScience Research Group, such as Dr. Richard Leiner, Clemens Jakobs and Prof. Alexander Zipf.
The society wants to strenghten the linkage between Citizen Science and institutionalized scientist and improve the involvement of citizens in sciencitific tasks. The focus will be mostly on Germany.
A first web site has ben set up to explain the ideas in some detail:
Spread the word and join the team!
Prof. Dr. Joao Porto, a computer scientist from University of Sao Paulo, Brazil has received a grant by Heidelberg University funded through the DFG Initiative of Excellence that allows him to stay as visiting professor at the GIScience Research Group of Heidelberg University through 2014 and then returning to Heidelberg several times until 2017. His reseach will focus on “Disaster Mapping 2.0: Collaborative Geographic Information Systems for Building Resilience against Disasters“. Joao has been at the GIScience Reseach Group already in 2013 as Humboldt scholar working on similar topics (Project AGORA). He was active with our crisis mapping activities through Typhoon Yolanda, e.g. the definition of elements at risk maps from OpenStreetMap and teaches courses related to disaster mapping. We are looking forward to further fruitful discussions and research through the next years! Welcome to Heidelberg (again).
Feb 3rd, 2014 by Bernhard Höfle
We invite you to participate in our workshop Digital Earth: What the hack?, as part of the 17th AGILE Conference on Geographic Information Science, 3-6 June 2014, Castellón, Spain.
The proposed workshop will prepare hackathons including geospatial information and processing across a variety of possible disciplines and thereby implementing Digital Earth applications. Hackathons are a promising tool for communicating (geospatial information) science and the engagement of society in research. They require detailed preparations and especially need clear challenges and methods in order to succeed. With this event, we initiate a coordinated discussion on the topic and provide the required groundwork for future realisations. We will particularly investigate possibilities for organizing parallel events as competitions between (smart) cities.
Further infos are provided here: Detailed Workshop Program
Rob Lemmens, ITC, University of Twente
Sven Schade, European Commission, Joint Research Centre
Florian Hillen, Universität Osnabrück Institut für Geoinformatik und Fernerkundung
Bernhard Höfle, Universität Heidelberg
Yola Georgiadou, ITC, University of Twente
Christine Richter, University of Amsterdam