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GeoNode – Incorporating Geovisualization in Support of SDI

Edward PICKLE

Abstract

GeoNode is open source geospatial software that provides free, robust software for devel- oping spatial data infrastructures. Originally engineered by OpenGeo and now a growing GeoNode developer community, its contributors are increasingly tasked with enhancing geovisualization – adding cartographic features to make compelling data displays, particu- larly of time series and natural disaster data, as vital to the project as enabling SDI. This pa- per provides an overview of how adding features to support visualization to an open source, collaborative software stack offers both considerable technical challenges and benefits in data discovery, spatio-temporal data viewing, data publishing and collaboration.

1 GeoNode: Origin, Development and Community Growth

The GeoNode software stack originated as an initiative of software provider OpenGeo and the World Bank to reduce disaster risk in Central America (CAPRA 2009). The GeoNode concept was that developing free open source software encourages spatial data infrastruc- ture creation by providing data holders with tools to easily load, visualize and share infor- mation, thus increasing the availability of data needed for disaster risk modeling (WORLD BANK 2010). GeoNode is based on open source components including GeoServer, GeoNet- work, Django, and GeoExt to provide web-based spatial visualization and analysis (PICKLE 2010). In 2010–2011 OpenGeo worked with numerous organizations to adopt the GeoNode plat- form and further grow the GeoNode open source community (PICKLE 2011). AIFDR, a transnational project to strengthen Indonesian capacity for natural disaster management, joined with OpenGeo, Geoscience Australia and the World Bank to develop a flexible, free, open source toolbox – “Risk in a Box” – to help evaluate disaster risks and build resilience. These tools included Risiko – an impact calculation engine and calculator, and TsuDAT, a Tsunami modeling tool (RISK IN A BOX 2012), and spurred GeoNode community work on bulk data uploading, versioned data editing, map/PDF integration, and crowd sourcing of exposure data.

Another addition to the GeoNode community was the Harvard WorldMap program (RUELL 2012). WorldMap heavily customizes GeoNode to create a “permeable membrane for data sharing across the research lifecycle” (LEWIS 2011), and serves a global base of scholars seeking to more generally explore, visualize, edit, collaborate with, and publish geospatial information. WorldMap moves GeoNode towards an important visualization element – allowing for the georeferencing of paper maps, a previously inaccessible geospatial re- source – online using the WorldMap WARP tool (WORLDMAP WARP 2012). The tool

Jekel, T., Car, A., Strobl, J. & Griesebner, G. (Eds.) (2012): GI_Forum 2012: Geovizualisation, Society and Learning. © Herbert Wichmann Verlag, VDE VERLAG GMBH, Berlin/Offenbach. ISBN 978-3-87907-521-8. 126 E. Pickle allows scanned historical maps to be geo-rectified for overlay on common online base maps (, etc.), and shared via WorldMap (Fig. 1).

Fig. 1: WorldMap Geo-referencing of Historical Giza Map on Google Base Map

2 Geovisualization Challenges for Spatio-Temporal Data

Cartographers have a of innovative visualizations to convey spatio-temporal data. Minard’s 1861 depiction of Napoleon’s invasion of and retreat from Russia (TUFTE 1983) is an ingenious portrayal of human loss against a field of space and time (and temperature) and pushes the limits of pen and ink “technology.” Computerization has enabled enhanced options for displaying dynamic data. In the 1970’s geographers used holographic techno- logy to portray US population change over time and space, and in the 1960’s used motion pictures to portray dynamic land change information over space (CHRISMAN 2006). Computer visualization creates a medium for portraying complex time/space data, a means of exposing knowledge from web enabled communications and collaboration (LANGEN- DORF 2001), and expanded methods for drawing discoveries from complex multi-dimen- sional data sets (MCCORMICK, et al. 1987). But, enabling cartographic visualizations on the modern, collaborative web means equipping both expert and non-expert cartographers with tools for preparing and visualizing data. GeoNode was developed for web-based collabora- tion and spatial data creation, but a recent community member, The MapStory Foundation, brought new, complex visualization requirements. GeoNode had been successfully used by AIFDR’s GeoNode-based TsuDAT tool to make compelling visualizations to local decision makers (e.g., city planners) that combined data provided from the federal level about global/regional phenomena (tsunamis) with their own data (DEMs, etc.) to determine what could affect them spatially (inundation) and under what temporal conditions (wave speed) (RISK IN A BOX 2012). However, the time element is generated by model calculations, not inputted time series data. MapStory required GeoNode to increase its capabilities by re- quiring cartographic animation and new, more flexible data handling needs for a hetero- geneous user base.

3 MapStory: New Visualization Needs and Challenges

The MapStory Foundation engaged OpenGeo to further develop GeoNode to power re- search into socio-cultural dynamics, promote better education on population groups and more (MAPSTORY 2012). Key to MapStory’s requirements is visualization of spatio-tempo- GeoNode 127 ral data by users possessing a wide range of technical expertise. This leads to an entirely new and challenging line of GeoNode software development. MapStory’s mission contains an analog to GeoNode’s mission – providing better geospatial tools to data holders so that they are motivated and equipped to upload and web-enable information – but extends it to include the sharing and visualization of dynamic data. In MapStory’s case these include data on populations and cultures heretofore locked away in academic papers, on desktop computers, and other environments isolated from the web and potential collaborators. MapStory’s ambitious vision is to develop MapStory as an online social media platform that enables a community of experts to “crowd source” socio-cultural data within a geo- spatial and temporal framework and to enable students, teachers and practitioners to com- municate sociocultural dynamics and data as powerful narrative “MapStories,” providing not just map portrayals but also shared data and web services. MapStory requires GeoNode to represent data in a standardized, searchable format (including geospatial and temporal/chronological searches) and in such a way that data can easily be accessed, analyzed and visualized – particularly geospatially and temporally. Many of these requirements are standard GeoNode functionality or are already on the de- velopment roadmap. However, the temporal aspects imply new functionality including easier uploading of data with specialized tools for time series and time-stamped geo-refer- enced user annotations, simple to use time controls, more flexible and robust data styling, and fast caching for animation. In order to support proper display and visualization of temporal information, users must be able to upload datasets with appropriate temporal encoding into GeoNode and have them properly configured in GeoServer for use with (WMS). Before MapStory, GeoNode’s upload functionality was based on GeoServer’s REST configuration API, but the MapStory use case indicated that user prompts for input would be essential for the majority of users to successfully load temporal data, requiring new software code. New functionality also makes temporal data with a time attribute encoded as ISO 8601 easily handled, while for other formats a facility for users to manually identify the time attribute and request "Best Guess" during the import process was added.

Also, while the current GeoNode uploader accepts Shapefiles as individual files or in zip- ped form (along an optional SLD), it was refactored to be more extensible, making future format support significantly easier to implement. A timeline (which runs along the bottom of the map and shows temporal context) was integrated to provide users with broader tem- poral context while the map shows the state of things at a specific time (or in a specific range) (Fig. 2).

Fig. 2: Visualizing phenomena in map and time series simultaneously 128 E. Pickle

Additionally, spatially referenced annotations allow further context to be inserted inde- pendent of the data. As a result of these code improvements, MapStories can be told on the map, in the timeline, or both, with queries triggered on the map triggered on the timeline, and vice versa. As a result of MapStory requirements, OpenGeo has extended GeoNode software to not simply display spatial or temporal data, but to allow a complete visualization of temporal, social, and narrative content in a dynamically inclusive way. For example, a map showing how type of government and areas of conflict change over time and space in twentieth-cen- tury could inform further inquiry about the relationship between both seemingly un- related datasets. These hypotheses and a wealth of others can then be animated and anno- tated to tell stories that encourage feedback from peers across the MapStory site.

References

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