Spatiotemporal data animation

[From @pzwang, 11/2015]

Could basically look like this, with some graphical controls to change aspects of the animation. Really, parameters of the animation are just additional variables for the transfer function.

http://earth.nullschool.net/#current/wind/surface/level/orthographic=-94.43,29.75,1806

Would be awesome to just be able to use their front-end code (not sure about license, feasibility, or desirability from a code quality perspective). Otherwise we'd have to do some webGL-fu on our end...

I don't think this animated form should be the _only_ view of spatiotemporal data, but it should be one of the main ones available (possibly even the default view). Mating this to the backend engine in a generic way for many datasets will be the bulk of the work.

Another potential UI paradigm that we should think about is based on the Mac OS/iTunes "coverflow" approach, where we offer a time slider and the user can move back and forth between different time points: http://vanderlee.github.io/coverflow/ Each image itself would be an interactive view of the map at that point in time.

The UI should also include a time track that shows histogram of all points/tracks regardless of position (could be called "motion histogram"). The user can draw selection regions to drill down and filter what is shown in the main map view (whether that main view is doing the animated nullschool thing, or is represented as coverflow, or something else). This should use datashader, so the user can script filters that only tracks of a certain length or with a certain average velocity, get shown.