Cartographic visualization.ppt

1、Cartographic visualization,Dmitry Nekrasovski March 24, 2004,So what is it?,Which of these is a cartographic visualization?,Different maps, same domain,Visualization methods for interacting with geographic information(MacEachren, 1998),Applying cartographic principles to visualization of non-geograp

2、hic information (Skupin, 2000),Why cartographic viz?,Dynamic, interactive visualization of geospatial information F+C, linked highlighting, fluid navigation Spatial visualization of non-geospatial data Cartographic principles,Papers,Cartographic Perspectives on Information Visualization (Skupin, 200

3、0) Where on Earth is the Internet? (Dodge & Shiode, 1998) HealthVis (MacEachren et al., 1998),Map metaphors for non-geo data,Timeline Late 1800s: Intellectual domains (Otlet) 1980s: Early hypertext systems 1990s: Mapping/spatial metaphors in infoviz Cartographic principles rarely applied “Readings i

4、n Infoviz”: 3 references,Scaling,“The major usability problem” Tradeoffs between: Number of features Size of symbols Size of display area Cartographic generalization: Preserve meaning at different scales,Example,Projection,Cartography: 3D-2D Mercator: angular relationships (directions) Peters: relat

5、ive area Infoviz: nD-2D Multi-dimensional scaling (MDS): distance Self-organizing maps (SOM): topology,Labeling,Infoviz issues: Space, label positions, label terms Cartography Conventions to deal with these issues Coastal cities vs. cities near the coast Labels can add meaning to features Labels can

6、 help in evaluating visualizations Terrain visualization with only ridges labeled?,Paper critique,Strong points: Good overview of related issues/ideas in cartographic research Many basic cartographic references Weak points: Few specific guidelines No examples of actual systems When do these ideas no

7、t apply?,Papers,Cartographic Perspectives on Information Visualization (Skupin, 2000) Where on Earth is the Internet? (Dodge & Shiode, 1998) HealthVis (MacEachren et al., 1998),Where on Earth is the Internet?,Internet typically perceived apart from real-world geography Map Internet “real estate” ont

8、o real geospace Where are domains actually located? Possible impacts on cities/areas with high concentration?,Dataset,Domain registration records Not geographically referenced But contain physical contact information Postal codes extracted, mapped to location Also IP address allocation for each doma

9、in Entire UK domain registry as of 1997 10,183 records 44 million allocated IP addresses,Visualization 1,Density surface map Dot = record No context, low information density,Visualization 2,IP address density, more context,Paper critique,Strong points Map metaphor for non-geographic data Real-world

10、dataset Weak points Accuracy: IP allocation vs. actual use No interaction/navigation/filtering No time component No evaluation,Papers,Cartographic Perspectives on Information Visualization (Skupin, 2000) Where on Earth is the Internet? (Dodge & Shiode, 1998) HealthVis (MacEachren et al., 1998),Healt

11、hVis,Exploratory map-based visualization of variations in health statistics Death rates for various causes, risk factors Goal: Spatial and temporal analysis Spatial: easily find regions/clusters Time: compare changes over time Space+time: trends in regions/clusters over time,Linked views,Cross map,A

12、nimation for time series,Demo,Evaluation,Task-based exploration with domain experts Results: Spatial tasks easy with linked highlighting Animation good for noticing time trends Space+time trends more difficult,Paper critique,Strengths: Good analysis of issues in multivariate geographic data exploration Real dataset Detailed qualitative evaluation Weaknesses: Dense, some unclear terminology Effectiveness of cross maps? Evaluation focused on task, not system,Questions?,