Mapping Denali in Detail

Matt Nolan and his family have created a topographic map of Denali, the highest peak in North America, using a form of stereo photogrammetry Nolan calls fodar: they repeatedly overflew the peak in a small airplane and took photos of the terrain below with a digital SLR. The end result is a 20-cm terrain model they’re touting as the best ever of the mountain, far more detailed than previous maps. Nolan outlines their endeavour in two blog posts: one focusing on the personal, the other on the technical; the latter also has lots of terrain models and comparisons with USGS data.

He’s also running a crowdfunding campaign to underwrite the costs of additional map flights. [WMS]

LIDAR Mapping Reveals a Far Greater Mayan Civilization

A 2016 aerial survey of ten sites in Guatemala’s Maya Biosphere Reserve used LIDAR to digitally remove the tree canopy from the landscape, revealing, National Geographic reports, “the ruins of a sprawling pre-Columbian civilization that was far more complex and interconnected than most Maya specialists had supposed”—and one that likely supported a much higher population than previously thought. The survey and its findings are the subject of a documentary special premiering tomorrow on the National Geographic channel. More coverage: CBC NewsThe New York Times, The VergeThe Washington Post.

Urban Scratchoff

Using an interactive interface to compare present-day and historical maps and aerial imagery is done all the time—on this website I use a slider plugin—but Chris Whong’s Urban Scratchoff uses a familiar metaphor to compare present-day aerial images of New York City with imagery from 1924. Give it a try. More on how Chris did it. [via]