Pause Show land Use Tissot's Indicatrix Use Gedymin faces
This page is designed to illustrate map distortion using Tissot's indicatrix and the Gedymin faces. This web page is based on a few important sources. First, I made some changes to Jason Davis' code of the map projection transitions, which has been tremendously useful. Additional projections (mainly conic and azimuthal) were also used in this page following these examples. Second, I used Matthew T. Perry's Python code to create the Tissot's indicatrices in a shapefile. Third, the shapefile for the faces were created by Paul B. Anderson who also maintained a great repository for Gedymin faces. Fourth, the shapefiles were converted to GeoJSON in QGIS, and then to TopoJSON using a tool called topojson on Mac. The indicatrices data is available at here and the faces are available at here. The world countries data is from Natural Earth. The original Projection Transitions is made by Mike Bostock. In this version of the code, transitions to the azimuthal projections still need further adjustment. If anybody has a fix to that, please drop me a line.
Ningchuan Xiao | OCT 17 2015 | gis.osu.edu