Eagle Summit alpine tundra ~ortho mosaic by Chris Fastie

Canon Powershot A590 IS

This is a handmade more or less ortho photo mosaic of three 20x20m above-treeline alpine tundra study plots in the White Mountains of Alaska near Eagle Summit. There are five plots along this transect, all of which can be seen in this half-spherical gigapan: gigapan.org/gigapans/83270/ (which was made from a different set of photos).

This mosaic is made of 43 somewhat vertical photos taken by a Canon PowerShot A590 hanging from the line beneath a 9 foot delta kite. I manually aligned the photos over a grid of GPS points of the corners of the plots, which are flagged and visible in the photos. These points were from a consumer GPS receiver, so I nudged the corners into a tidy square for the two plots on the right. The images of the leftmost plot were uncomfortable being square, so I let them relax a bit. The alignment was done in Photoshop because I can't afford PhotoScan, and because the Cartagen Knitter (cartagen.org /) seemed to offer no advantage over PhotoShop for this effort.

The camera was 20-30 m above the ground, and the lens was zoomed all the way wide (35mm eq.). I then brought the camera closer to the ground and captured higher resolution photos of the center plot, outlined by a white tape, and parts of the other two plots. These photos are aligned on top of the larger photos, so the resolution varies across the image.

More info on the process is here: fastie.net/?p=1077 .