Feed on
Posts
Comments

The Chilean newspaper El Mercurio has released an article about Heidelberg’s research on VGI and Neogeography in their Science and Technology section in the issue of 14 July 2014.

El Mercurio, Santiago de Chile (No. 41.265), p. A11: Neogeografía: La geografía evoluciona al alero de las redes sociales.

The GIScience together with colleagues from Health & Society participated as team Geo4Health in the charity Run Against Cancer (NCT-LAUFend gegen Krebs) on 11 July 2014 organized by the National Center for Tumor Diseases (NCT). The run took place on university campus Im Neuenheimer Feld (2.5 km lap around the Theoretikum and University Hospital).

We are happy that we contributed - apart from our donation - 50 km to the incredible amount of total kilometers of all participants together. Results of the NCT run can be found here: http://my4.raceresult.com/details/index.php?page=4&eventid=25779&lang=de

We would also like to congratulate our GIScience student assistant Sophie Crommelinck and her team for the amazing performance over 5km and 10km!

A case study in rural Ghana

Access to skilled attendance at childbirth is crucial to reduce maternal and newborn mortality. Several different measures of geographic access are used concurrently in public health research, with the assumption that sophisticated methods are generally better. Most of the evidence for this assumption comes from methodological comparisons in high-income countries. We compare different measures of travel impedance in a case study in Ghana’s Brong Ahafo region to determine if straight-line distance can be an adequate proxy for access to delivery care in certain low- and middle-income country (LMIC) settings.

We created a geospatial database, mapping population location in both compounds and village centroids, service locations for all health facilities offering delivery care, land-cover and a detailed road network. Six different measures were used to calculate travel impedance to health facilities (straight-line distance, network distance, network travel time and raster travel time, the latter two both mechanized and non-mechanized). The measures were compared using Spearman rank correlation coefficients, absolute differences, and the percentage of the same facilities identified as closest. We used logistic regression with robust standard errors to model the association of the different measures with health facility use for delivery in 9,306 births.

Non-mechanized measures were highly correlated with each other, and identified the same facilities as closest for approximately 80% of villages. Measures calculated from compounds identified the same closest facility as measures from village centroids for over 85% of births. For 90% of births, the aggregation error from using village centroids instead of compound locations was less than 35 minutes and less than 1.12 km. All non-mechanized measures showed an inverse association with facility use of similar magnitude, an approximately 67% reduction in odds of facility delivery per standard deviation increase in each measure (OR = 0.33).

Different data models and population locations produced comparable results in our case study, thus demonstrating that straight-line distance can be reasonably used as a proxy for potential spatial access in certain LMIC settings. The cost of obtaining individually geocoded population location and sophisticated measures of travel impedance should be weighed against the gain in accuracy.

Reference

Nesbitt, R., Gabrysch, S., Laub, A., Soremekun, S., Manu, A., Kirkwood, B., Amenga-Etego, S., Wiru, K., Höfle, B. & Grundy, C. (2014): Methods to measure potential spatial access to delivery care in low- and middle-income countries: a case study in rural Ghana. International Journal of Health Geographics. Vol. 13 (1), pp. 1-13.

We are pleased to announce three upcoming talks. One of them is given by a guest from Melbourne, Australia. The other two talks are held by colleagues from university-internal partner institutions. All talks will be held in English. See more details on each talk below:

Talk 1:

“Sustainability Research in a World at Risk: The Melbourne Story (so far)“

Prof. Brendan Gleeson

Director | Melbourne Sustainable Society Institute, University of Melbourne

Wed. 9.7.2014, 14.15 h

Location: Institute of Geography Lecture Hall, Berliner Str. 48



Talk 2:

“Image Processing Approaches for Measuring Atmospheric Transport Processes from Satellite Remote Sensing”

PD Dr. Christoph S. Garbe

Image Processing and Modeling, IWR, Heidelberg University

Thu. 10.7.2014, 13.15 h

Location: Institute of Geography, Lecture Hall, Berliner Str. 48


Talk 3:

“Archaeological Information Systems and Digital Cultural Heritage”

Dr. Armin Volkmann

Cluster of Excellence “Asia and Europe in a Global Context”, Heidelberg University

Thu. 17.7.2014, 16.15 h

Location: Institute of Geography, Lecture Hall, Berliner Str. 48

Mr. Mon-Shieh Yang, a senior PhD candidate from the National Cheng Kung University (NCKU), Department of Earth Sciences, has been awarded a grant of the National Science Council (NSC) of Taiwan to join the LiDAR Research Group (LRG) of the Chair of GIScience Heidelberg from July 2014 to April 2015.

His research will focus on the investigation of LiDAR point cloud data to develop novel 3D GIScience methods for the extraction of surface properties (e.g. surface roughness), which are of major relevance for geomorphological, hydraulic and engineering applications in Taiwan.

Mon-Shieh, Welcome to Heidelberg and our GIScience team!

Talk within the Colloquium GIScience on

An Attempt to Use InSAR Methods to Detect Vertical Movements in Arctic Permafrost Regions

by Inga May, Alfred-Wegener Institute (AWI) Potsdam

Wednesday, 23.07.2014, 11:15-12:00h, Hörsaal Geogr. Institut, Berliner Str. 48

As permafrost is a subsurface phenomenon, and not directly visible from space, surface features, representing the permafrost situation underneath, have to be identified. Therefore a variety of ground-truth measurement is required to interpret the satellite images and to assess potential changes in the permafrost. One common approach is the analysis of optical imagery at different scales, taking into account changes in the vegetation, snow cover, and geomorphological units such as thermokarst ponds and frost mounds. A rather new method is the use of InSAR methods to detect frost-heave or subsidence caused by thawing. InSAR has been applied in Polar Regions to identify horizontal displacements of e.g. glaciers, but vertical movements have not been studied before. For her PhD thesis Inga explored the possibilities to use TerraSAR-X data to generate differential interferograms that could provide information about such changes in the relief. High precise GPS records served as reference. The study revealed that due to the many factors influencing the radar signal, it is very complicated to get adequate results, and the outcomes have to be taken with care. However some interesting results showing frost-heave in winter and subsidence during the summer months could be achieved.

Dr. Inga May studied Physical Geography at the University of Munich, got his PhD in polar research and works today as postdoc at the Alfred-Wegener Institute in Potsdam. Her research focus is mainly on studying to which extend optical and radar satellite data is feasible to detect permafrost dynamics in high latitudes.

Last friday our former team member Arne Schilling successfully defended his PhD! Congratulations for that! The topic was about “3D Spatial Data Infrastructures for Web-Based Visualization” and included his work on developing SDIs for 3D landscape and city models evaluating and advancing OGC proposal for 3D visualization like the Web 3D Service (W3DS) and integrating it with further OGC web services for building web-based 3D GIS applications. His work in projects like “GDI-3D” also included developing several new algorithms for processing 3D terrain and landscape models. Results can be experienced by downloading the W3DS client XNavigator that allows to visualize e.g. Heidelberg-3D, Sutren-3D or OSM-3D.

If you followed our previous posts (#1, #2) concerning high quality cartographic label placement, then this post is worthy of notice.

Topographic maps are arguably one of the most information-dense, yet intuitively usable, graphical artifacts produced by mankind. Cartography as science and practice has developed and collected a wealth of design principles and techniques to cope with the problems of high graphical density, especially for the case of label placement. Many of the more sophisticated techniques that take into account figure-ground relationships for lettering have not been fully operationalized until now. We present a novel generic quality evaluation model that allows full automation of refined techniques for improving map feature overlap, visual contrast and layer hierarchy. We present the objective function as a set of metrics corresponding to the design principles and provide exemplary parameterization via the set of experiments on global real-world datasets. The approach designed for labeling of point-like objects and can potentially be applied to linear and areal features. It has a low computational and memory requirement. Furthermore, it is conceivably applicable to annotate any kind of visualization beyond maps. The results of the conducted tests and comparison with a commercial labeling package such as Maplex illustrate the ability to produce highly legible and readable map lettering with our approach. Presented method heeds more cartographic design principles and is computationally less costly compared to commercially available methods (e.g., ESRI’s Maplex or Maptext’s Label-EZ).

Below we provide two images which demonstrate some capabilities of the proposed approach.

A sample label placement without considering background features.

A sample label placement without considering background features.

A sample label placement with considering background features.

A sample label placement with considering background features.

A web map labelled using the presented approach is available at OpenMapSurfer web page (see OSM Roads layer, zoom levels 2-12).

Reference: Rylov, M. & Reimer, A. (accepted) “Improving Label Placement Quality by considering Basemap Detail with a Raster-Based Approach.GeoInformatica. doi: 10.1007/s10707-014-0214-6.


News for the GIScience PhD students in Heidelberg: the formal examination rules for PhD dissertations at our faculty now officially include the topic “Geographic Information Systems” as one of only four areas of specialization (next to Physical Geography, Human Geography and Regional Science) for PhDs at the Institute of Geography.

  • How can we explore geographical relations between social media and authoritative data to enhance information extraction for disaster management?
  • How can collaborative maps of OpenStreetMap be used for supporting risk analysis and emergency planing?

These two questions were explored recently by researchers of the GIScience group working on the use of Volunteered Geographic Information for Disaster Management and in the AGORA project.

Prof. João Porto de Albuquerque, visiting professor at Heidelberg, presented two papers related to the use of volunteered geographic information for disaster management at the conference Information Systems for Crisis Response and Management (ISCRAM 2014). The first one is entitled “Does the spatiotemporal distribution of flood-related tweets correspond to the spatiotemporal distribution of floods? A study about the River Elbe Flood in June 2013“. It explores the use of geographical relations between twitter messages and sensor data from official water gauges to reveal that the distribution of flood-related tweets is well related to the distribution of flooded areas, as we can notice in the figures below.

Spatiotemporal distribution of flood affected catchments

Spatiotemporal distribution of flood affected catchments

Spatiotemporal distribution of non-related and flood-related tweets

Spatiotemporal distribution of non-related and flood-related tweets

A work further elaborating on this research question called “Exploring the geographical relations between social media and flood phenomena to improve situational awareness: A study about the River Elbe Flood in June 2013 was presented as a full paper at AGILE conference in Castellón (Spain) by Benjamin Herfort, undergraduate research assistant of the GIScience group.

Another paper presented at ISCRAM 2014 was related to “Identifying Elements at Risk from OpenStreetMap: The Case of Flooding“, where we examine how OSM can be used for risk analysis and emergency planing. This topic was also presented at State of the Map Europe, the main conference related to OpenStreetMap in Europe. The video recording of this talk is available here.

Last but not least, we are currently running a course on Disaster Mapping 2.0, for which the students are having very interesting discussions in a blog. Everybody is welcome to contribute!

Paper References:

HERFORT, B., ALBUQUERQUE, J. P., SCHELLHORN, S., ZIPF, A. (2014) Does the spatiotemporal distribution of flood-related tweets correspond to the spatiotemporal distribution of floods? A study about the River Elbe Flood in June 2013. In 11th International ISCRAM Conference – University Park, Pennsylvania, USA.

HERFORT, B., ALBUQUERQUE, J. P., SCHELHORN, S., ZIPF, A. (2014) Exploring the geographical relations between social media and flood phenomena to improve situational awareness: A study about the River Elbe Flood in June 2013. In 17th AGILE Conference on Geographic Information Science: Connecting a Digital Europe through Location and Place.

SCHELHORN, S. J.; ALBUQUERQUE, J. P.; ZIPF, A.; LEINER, R.; HERFORT, B. (2014): Identifying Elements at Risk from OpenStreetMap: The Case of Flooding. In 11th International ISCRAM Conference – University Park, Pennsylvania, USA.

Older Posts »