Historic England’s Aerial Photo Explorer

Historic England’s new Aerial Photo Explorer allows users access to an archive of some 400,000 digitized aerial photographs taken over the past century. From their announcement: “Aerial imagery provides a fascinating insight into the development and expansion of the nation’s urban centres and changes to the rural landscape. It can also reveal striking discoveries—such as ‘cropmarks’ showing hidden, archaeology beneath the surface.” I notice that it also includes aerial photos of World War II bomb damage.

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]