Sometimes we stumble upon interesting things and we don’t necessarily know how we should use what we have just found. A series of maps; snow cover in Canada was an interesting find but not really all that useful for any of my personal projects. However, I eventually came back to it when I realized that not all geovisualizations occur within a GIS environment.
Natural Resources Canada (NRC) released a series of snow cover map collections on their GeoGratis portal. I proceeded to connect to the portal via FTP and downloaded the 2007 snow cover series. The maps are .HDF.PNG format, which easily import into a GIS for processing, however this was not my goal. I wanted to create a video timeline of the snow cover extent in Canada from the 365 maps that I just downloaded.
Using ffmpeg, I was able to string the series of maps together into a video. If you’re interested, the code looks a little bit like this:
ffmpeg -r 10 -b 1800 -i %03d.png test1800.mp4
This code only works if your series of images start at 001.png! Make sure that there aren’t any missing files in your series (ie. If image 012.png is missing, the video will stop encoding after image 011.png). To change the filenames of the maps that I downloaded, I used Automater (built into Mac OS X) to process a batch conversion.
Heres the video!