Watch Ka Roimata o Hine Hukatere, Franz Josef Glacier, as it flows from high in the mountains, pushing up over bedrock bumps, and down through the once Great Icefall, now separated in two by the 'Black Hole', a bedrock knob. Some ice melts at the surface, some is lost at the edges of the Black Hole, some falls into a waterfall at the glacier margin, but most of the ice continues down to feed the terminus. But this great flow of ice is not enough to maintain glacier's length -- more ice melts at the low-elevation terminus than is supplied from snowfall at the top, so the glacier retreats.
The image sequence, taken over a year and a half (January 2013 to June 2014), is repeated four times in this video. Made by Victoria University of Wellington with the support of Franz Josef Glacier Guides, Department of Conservation, Snowgrass Solutions, and the Marsden Fund.
The camera system used to take these images consists of a Raspberry Pi (raspberrypi.org), a low cost credit-card sized computer, controlled by an Arduino (arduino.cc/), an open-source electronics platform. The arduino acts as a GPS-synchronised timer, booting up the raspberry every hour and passing the time through the serial port. The raspberry uses the gphoto2 library to capture the image (on a Nikon D5100 camera), and the photos are uploaded to the internet through a wireless telemetry system. The first camera system, installed in November 2013, has taken 14 photos a day for more than 2 and a half year without fail (and without any maintenance!).