Visual Design of Small-scale World Map Projections

Project in collaboration with Tom Patterson, U.S. National Park Service.

Goals

Algorithms and methods for customizing cylindrical, pseudo-cylindrical and polyconical map projections for world maps. Methods for rating and comparing map projections for specific use cases.

Results

An interactive method for the customization of the shape of projection graticules was developed. The length and vertical distribution of parallels, as well as the concave or convex bending of parallels, and the distribution of meridians can be adjusted interactively. New projections can be generated from scratch, or existing ones can be changed. A projection mixer allows for the blending of selected features to combine advantageous properties of two projections. Specialized tools for the evaluation of projection characteristics and for the comparative rating of projections have been developed.

The method was implemented in Flex Projector, an open-source application developed in Java.

flexprojector

The Flex Projector interface.


naturalearth

Natural Earth projection designed with Flex Projector by Tom Patterson.

Detailed Project Description

The design of new map projections has until now required mathematical expertise that has limited this activity to a small group of specialists. The Institute of Cartography developed a new software-based method, enabling cartographers to easily design new world map projections. A new projection is designed interactively in an iterative process, which allows the designer to graphically and numerically assess the representation of the continents and the graticule (the network of lines of latitude and longitude upon which a map is drawn). The devised concepts were implemented in Flex Projector, a specialized free and open-source software application for the design of new world map projections. It enables users to quickly create new map projections and modify or combine existing projections. Flex Projector also offers complementary visualizations and numerical evaluation methods that illustrate the distribution and amount of the inevitable areal and angular distortion and help the projection designer optimize a projection. Flex Projector was used to create various new map projections, for example the Natural Earth projection, which is a pseudocylindrical projection with a balanced appearance of major landmasses. It was decided to give the corners, where the pole lines and bounding meridians meet, a rounded appearance. The rounded corners suggest that the projection represents a spherical earth, and reduce the size of polar areas, thereby reducing the areal exaggeration of Antarctica.

Publications

Jenny, B., Patterson, T. and Hurni L. (s.d). Graphical design of world map projections. International Journal of Geographic Information Science [accepted for publication].

Jenny, B., Patterson, T. and Hurni L. (2008). Flex Projector—Interactive software for designing world map projections. Cartographic Perspectives, 59, p. 12-27 and 68. PDF.


Website

Flex Projector (2007) www.flexprojector.com
Flex Projector is software for the design of small-scale map projections.
Authors: Bernhard Jenny, Tom Patterson (US National Park Service)