Presentation on theme: "“Alternative” Data Structures. Information Spaces / Spatialization www.smartmoney.com."— Presentation transcript:
“Alternative” Data Structures
Information Spaces / Spatialization
Information Spaces / Spatialization Chen et al. 1998
Information Spaces / Spatialization
Alternative Data Structures (especially w/ increased processing speeds, storage)
Thiessen (Voronoi) Polygons and Delaunay Triangles they divide the space between the points as ‘evenly’ as possible –market area delimitation, rain gauge area assignment, VIPs DTs are as near equiangular as possible, thus minimizes distances for interpolation elevation, slope and aspect of triangle calculated from heights of its three corners A Thiessen neighbors of point A share a common boundary. Delauney triangles are formed by joining points to its Thiessen neighbors. A Thiessen Polygons Delaunay Triangles
partition areas based on “influence” of sample points (Thiessen polys) all sample points connected w/ 2 nearest neighbors to form triangles connect centroids of Thiessen polygons market area delimitation, rain gauge area assignment, trusted elevation benchmarks or VIPs, etc.
1.Draw lines connecting the points to their nearest neighbors. 2.Find the bisectors of each line. 3.Connect the bisectors of the lines and assign the resulting polygon the value of the center point Thiessen Polygon Start: 1) 2)3)
Sampled locations and values Thiessen polygons Daniel P. Ames, Dept. of Geosciences (Geology), Idaho State University
Visualization of Theissen Concept Arthur J Lembo, Jr., Bowne
Inverse Distance Weighting Arthur J Lembo, Jr., Bowne
Kriging Arthur J Lembo, Jr., Bowne
Perspective Plot from TIN
TIN (Triangulated Irregular Network) avoids redundancy of raster while still producing a continuous surface more efficient than raster for some terrain analysis –slope and aspect (faces of triangles) –contouring Measurements are irregularly spaced with more sampling in areas of greater complexity –requires fewer points or grid cells
Contours from TIN (triangles can be many and extremely small with a good sampling of points)
Computers love rasters A cell on 1 map is at same position on all others Easy query, neighborhood ops., etc.
Consistency/Uniformity great for computers but what about human psyche? Can we bear such generalization? Cartographic Heresy?
Compression: Run Length Encoding based on spatial autocorrelation –nearby things tend to be more similar than distant things data entered as pairs –run length & value 40 items instead of 70
way of encoding irregularity of vector in raster form step beyond run-length-encoding compression compress in row AND column directions
Raster to Quadtree
Divide into sub-quadrants focusing on irregularity
Quadtrees of Chloropleth Raster Map NWNESWSE NWNE SWSE Marc van Kreveld, U. of Utrecht
Gateway to the Literature “information spaces” Information space partitioning using adaptive Voronoi diagrams, Information Visualization, Reitsma, R. and Trubin, S., Information space partitioning using adaptive Voronoi diagrams, Information Visualization, Dodge, M., and R. Kitchin, Code and the transduction of space, Annals AAG, 95 (1), , Fabrikant, S.I., and B.P. Buttenfield, Formalizing semantic spaces for information access, Annals AAG, 91 (2), , Skupin, A., On Geometry and Transformation in Map-Like Information Visualization. In: Börner, K., Chen, C (Eds.) Visual Interfaces to Digital Libraries. Lectures in Computer Science Springer Verlag, Berlin , 2002 Skupin, A., On Geometry and Transformation in Map-Like Information Visualization. In: Börner, K., Chen, C (Eds.) Visual Interfaces to Digital Libraries. Lectures in Computer Science Springer Verlag, Berlin , 2002.
Gateway to the Literature “natural spaces” Chen, J., C. Li, Z. Li, and C. Gold, A Voronoi-based 9-intersection model for spatial relations, Int. J. Geog. Inf. Sci., 15 (3), , voronoi_ijgis.pdf Chen, J., C. Qiao, and R. Zhao, A Voronoi interior adjacency-based approach for generating a contour tree, Comp. Geosci, 30, , –voronoi_contour_tree.pdf Gold, C.M., and A.R. Condal, A spatial data structure integrating GIS and simulation in a marine environment, Mar. Geod., 18 (3), , Mostafavi, M.A., C. Gold, and M. Dakowicz, Delete and insert operations in Voronoi/Delauney methods and applications, Comp. Geosci, 29, , voronoi_2003.pdf Zhang, H., and C. Thurber, Adaptive mesh seismic tomography based on tetrahedral and Voronoi diagrams: Application to Parkfield, California, J. Geophys. Res., 110 (B04303), doi: /2004JB003186, seismic_mesh.pdf
Dynamic Segmentation multiple attributes to a single arc... attribute to a portion of an arc...
DynSeg: Measures & “Events”
DynSeg: Point Events
DynSeg: Single Arc, Multiple Attributes
Heceta Bank, Oregon
Heceta Bank Fisheries Investigations M.S. Theses: Nasby, 2000; Whitmire, 2003 At what scales are there quantifiable relationships between groundfish populations and seafloor morphology/texture? What are the factors that control these relationships? What changes may have occurred in the fish populations after a decade? What are the characteristics and extent of natural refugia?
EM 300 Multibeam Bathymetry Depth Range: – m Gridded to 5 and 10 m Nasby, 2000; Whitmire, 2003