||Hexagon Mosaic Maps for Display of Univariate and Bivariate Geographical Data.
Carr, D. B. ;
Olsen, A. R. ;
White., D. ;
||ManTech Environmental Technology, Inc., Corvallis, OR. ;Technical Resources, Inc., Rockville, MD. ;George Mason Univ., Fairfax, VA. Center for Computational Statistics.;Corvallis Environmental Research Lab., OR.;National Science Foundation, Arlington, VA.
||EPA-68-C8-0006 ;EPA-68-C0-0021; EPA/600/J-94/167;
Mosaic mapping ;
Geographic distribution ;
Statistical data ;
Acid rain ;
Ray-glyph maps ;
||Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy.
The paper presents concepts that motivate the use of hexagon mosaic maps and hexagon-based ray-glyph maps. The phrase 'hexagon mosaic map' refers to maps that use hexagons to tessellate major areas of a map, such as land masses. Hexagon mosaic maps are similar to color-contour (isarithm) maps and show broad regional patterns. The ray glyph, an oriented line segment with a dot at the base, provides a convenient symbol for representing information within a hexagon cell. Ray angle encodes the local estimate for the hexagon. A simple extension adds upper- and lower-confidence bounds as a shaded arc bounded by two rays. Another extension, the bivariate ray glyph, provides a continuous representation for showing the local correlation of two variables. The theme of integrating statistical analysis and cartographic methods appears throughout the paper. Example maps show statistical summaries of acidic deposition data for the eastern United States. These maps provide useful templates for a wide range of statistical summarization and exploration tasks. Correspondingly, the concepts in the paper address the incorporation of statistical information, visual appeal, representational accuracy, and map interpretation.