Interactive video maps: <i>A year in the life of Earth's CO₂</i>

<p>This article introduces interactive video maps for the web. The main component of video maps is a video stream that is <i>areally</i> georeferenced to a spatial reference system in the same way rectified raster orthoimages are georeferenced. The areal georeference allows for interactivity that goes beyond the play, pause, and stop functionality of video player software. We highlight two types of functionality, allowing the user to (1) combine the video stream layer with other raster and vector map layers and (2) adjust the projection of the map in real time. We exemplify video maps by <a href="http://dx.doi.org/10.1080/17445647.2016.1157323" target="_blank"><i>A Year in the Life of Earth's CO₂</i></a>, an interactive video map that visualizes the results of a high-resolution NASA computer model of global atmospheric carbon dioxide distribution. The map shows how carbon dioxide travels around the globe over the course of one year. We use a combination of WebGL, a programming interface to the hardware-accelerated graphics pipeline, and HTML5 video for adding an areally georeferenced video layer to other map layers, and for the on the fly projection of the video stream in the web browser.