Projection Wizard: Map Projection Selection Tool

Bojan Šavrič
Bernhard Jenny
Helen Jenny
Oregon State University
Cartography & Geovisualization Group
NACIS PCD Pittsburgh 2014

projectionwizard.org

The selection criteria for map projections are a mystery to most GIS users. Map projections ought to be selected based on the map's geographic extent and the required distortion properties. This presentation will introduce the Map Projection Selection Tool, a web based tool that facilitates the selection of a projection. The user can select a map's geographic extent by adjusting the rectangular border on a web map or by entering the extent's geographic coordinate boundaries into the user interface. Based on the selected distortion property, the application returns a proposed projection, along with the projection parameters and, if applicable, a PROJ.4 library code. Leaflet open-source JavaScript library and National Geographic Basemap by Esri are used for the web map.

Transcript

1. Projection Wizard: Map Projection Selection Tool Bojan Šavrič Bernhard Jenny Helen Jenny NACIS PCD, Pittsburgh October 8, 2014
2. Furuti, C. (2013). Map Projections. Online: http://www.progonos.com/furuti/MapProj/CartIndex/cartIndex.html (accessed April 23, 2013)
3. Snyder’s Selection Guidelines Snyder, J. P. (1987). Map Projections – A working manual. US government printing office: p. 383.
17. Selection Criteria •  Extent of the geographic area •  Central latitude of the rectangle
18. Selection Criteria •  Extent of the geographic area •  World, small-scale map •  Hemisphere, medium-scale map •  Continent or smaller areas, large-scale map
19. Selection Criteria •  Small-scale map projection •  World projections, normal aspect
20. Selection Criteria •  Medium-scale map projection •  Azimuthal projection, oblique aspect
21. Selection Criteria •  Large-scale map projection •  Aspect ratios and map orientations: •  East-west extent, landscape-oriented map •  North-south extent, portrait-oriented map •  Equal extent, square-shaped map
22. Selection Criteria •  Equal extent, square-shaped map •  Azimuthal projection •  Polar areas: polar aspect •  Equatorial areas: normal aspect •  Other areas: oblique aspect
23. Selection Criteria •  North-south extent, portrait-oriented map •  Cylindrical projection, transverse aspect
24. Selection Criteria •  East-west extent, landscape-oriented map •  Polar areas: •  Azimuthal projection, polar aspect •  Equatorial areas: •  Cylindrical projection, normal aspect •  Other areas: •  Conic projection, normal aspect
25. Selection Criteria •  Distortion properties •  World extent •  Equal-area, equidistant, compromise •  Hemisphere extent •  Equal-areas, equidistant •  Continent or smaller areas •  Equal-area, conformal, equidistant
27. Credits •  Leaflet (web map) •  National Geographic, Esri, etc. (web map tiles) •  Leaflet.draw plugin (modified) •  D3 (preview map) •  jQuery (user interface)
28. Thank you! projectionwizard.org cartography.oregonstate.edu