Most of the work I have done in the last month has involved creating suggested sample applications in the spirit of learning the ropes. Andrew Bell has been giving me assignments. First up, create a globe and map earthquake data onto it.
I had done something similar a while back in Processing but my data was limited to California and Nevada. Now I would be working with 7 days worth of data from all around the world for any earthquakes with a magnitude of 2.5 or higher. It isn’t a huge amount but I would have to find ways to deal with the clusters that are associated with any earthquake data visualization.
Creating the actual globe was great fun. I was pointed towards NASA’s Blue Marble project. There you can download Earth textures at astronomical sizes. Some are available at 86400×43200 pixels. I grabbed a color map and a height map. Using NormalMappr, I created an additional normal map from the height map.
The one drawback of the NASA data is the river systems aren’t as prominent as I would have liked. I ended up adding in the rivers and smaller lakes using this image as a source.
As I mentioned earlier, earthquakes come in clusters. The Dominican Republic had a few dozen 3.0M to 4.0M quakes in that week. If I just stuck pins exactly over the epicenter, all of the Dominican Republic pins would be reduced to a single blurry pin which would not give an accurate summary of the area.
I decided to go back to my old friend Magnetism. In order to keep the quakes grouped but individually distinct, I anchored the pin to the epicenter but allowed the other end to drift a short distance away. This distance would be determined by making each pin-head magnetic so that it pushes away its neighbors’ pin-heads.