Animated Acancia-Hurricane Interactions

Despite the lack of support for temporal GIS in the free, non-subscription version of ArcGIS Online, ArcMap does support the creation of videos that can be uploaded to free blogs like this one or to video sites like YouTube. To create a video, users zoom to the desired area of the GIS, such as the North Atlantic, and then open the Time Slider window to set controls such as time extent, interval, and window. They then use the Animation toolbar to select Create Time Animation. The Animation Controls and Animation Manager, available through the same toolbar, allow adjustment of variables like the length of the animation in real time and playback time. Export Animation opens a dialog box to set the video format, choose compression options, and save the video.

I exported such a video focused on the North Atlantic with the route and daily position symbols for the Acancia and the HURDAT layers turned on using August 1 through September 5, 1893 as the time extent and 1 day as the time interval and window. The result was AcanciaAug1893.avi, which shows the vessel's day-by-day progress along its route line with hurricanes tracking nearby. Since each 24-hour time window has two noontime position markers, the current and previous day's noontime positions are visible on each frame, allowing users to visualize the daily progress of the Acancia along its route. Similarly, since each hurricane has several positions per day in HURDAT, at 6 hour intervals, the time settings allow users to visualize the evolution of the hurricane tracks through time and space even without the equivalent of a hurricane route line.

AcanciaAug1893.avi was 950 MB in size, however, far in excess of the 100 MB upload limit for this blog. I therefore opened it in Windows Live Movie Maker, included in the most recent versions of MS Windows and available from Microsoft as a free download, to reduce the file size. After adding some title frames, I saved it as AcanciaAug1893.wmv, only 8.3 MB, and uploaded it to this blog.

The result allows readers to view an animated version of the crossing of the North Atlantic by the Acancia in August of 1893 that is fairly identical to what they would see using the time slider in ArcMap. The resolution is lower and the user cannot pan, zoom, or control the time animation as fully as in ArcMap, but the video nonetheless visualizes vessel-hurricane interactions. As the Acancia passed north of Bermuda into the mid Atlantic with its cargo of aguardiente, a tropical storm formed in its wake and tracked northward. To the south, several hurricanes arced westward from the Cape Verdes toward the Caribbean, Florida, and the Atlantic Seaboard. As the Acancia turned southward toward its destination, Montevideo, it sailed directly across that cordon of hurricanes, and on August 26th at noon came within 50 miles (80 km) of the eye of a category 2. After an eastward excursion from its southward course, the Acancia continued southward toward Montevideo.

Since users have much more limited control to pan, zoom, and so on than if ArcMap could be time enabled on ArcGIS Online, I created another video that focuses more closely on the mid-Atlantic encounter between the hurricane, the Acancia, and its crew in late August 1893.

In future posts, I will explore other ways to share the temporal aspects of the GIS on the Web.