Even though several examples of great circle visualizations exist by now, I had not seen the code of one made with ggplot2. Both solutions offered, here using plot and here using lattice, basically loop through the great circle lines ordered from low to high number of flights and overplot the lines with fewer counts, which are plotted in a light color with those with higher counts, which are plotted in a dark color.
In ggplot we can simply use the alpha parameter for transparency in combination with scale_colour_gradient to obtain a similar effect.
After last year’s experience with taking iPad to the field I am finally getting around to reporting back on the 4 week long field research experience with iPad this summer, when we were able to equip our whole field school team (the faculty, a graduate student TA, three undergraduate students and myself) with iPads. Goal for this year was to more extensively explore iPad as a team and to see where it might be useful as a research tool.
Recently I went over the page kindly maintained by jeffschuler to get a sense of the status of the Drupal Geospatial Modules. If I consider investing in developing a Drupal Webmapping, how much can I rely on modules to exist in the future?
The graph below shows that many more geospatial modules exist in versions for Drupal 6 than Drupal 7 — Drupal 7 looking more similar to Drupal 5. However, there are two new modules that exist only for Drupal 7, Geofield (alpha release, seeking co-maintainers) and Address field (beta release, actively maintained).