Geoscience Reference
In-Depth Information
Figure 9.8 Tissot Indicatrix of Web Mercator Auxiliary Sphere projection with dis-
tortion realized in Google Earth. Source: Based on Google Earth mapping service
© 2012 Google and Image © 2012 TerraMetrics, Data SIO NOAA US Navy NGA
GEBCO, ©2012 Cnes/Spot Image. Altered base image from Arlinghaus, S. L. and
Kerski, J. 2012.
Software in which one can traverse an image of the globe, such as Google
Earth, offers a dynamic way to both see Tissot-style distortion and simul-
taneously consider an inventory of what is available on the globe through
digital imagery. Figure 9.8 shows a visual sampling of projection distortion,
using Tissot's Indicatrix, of the Web Mercator Auxiliary Sphere projection
(Arlinghaus and Kerski, 2012). What appears to be poleward distortion in
the screen capture in the figure will change as one rotates the linked image
within the Google Earth software. Why is that? The igure in the topic is a
static image. Try moving (using a link at the end of this chapter) the Google
Earth surface around to see what happens to the pattern of red circles!
9.8 Sampling the environment: The degree confluence project
The Tissot Indicatrix samples the graticule at the global, or at least, the
small-scale level. A more recent project, called the Degree Confluence Project
Search WWH ::
Custom Search