Tag: satellite imagery

Blank Map Tiles Point to Locations of Xinjiang Detention Centres

Published on by Jonathan Crowe

As part of their investigation into China’s practice of detaining Uighur and other Muslim minorities in Xinjiang, Buzzfeed News journalists compared blanked-out areas in Baidu Maps with uncensored imagery from Google Earth and satellite data providers, and, after sorting through some 50,000 possible locations using custom web tools, built a database of some “428 locations in Xinjiang bearing the hallmarks of prisons and detention centers.” This article explains the methodology.

Blurring or removing map data to prevent people from seeing something important or sensitive is a pretty loud signal that there’s something important or sensitive to see there. Some five million Baidu Maps tiles were masked in Xinjiang alone—there’s a lot the Chinese government considers sensitive—which made the unmasking considerably harder. But not impossible.

NASA Maps the Damage from the Beirut Explosion

Published on by Jonathan Crowe
NASA/JPL-Caltech/Earth Observatory of Singapore/ESA

NASA has released a map of the likely extent of damage from Tuesday’s explosion in Beirut.

Synthetic aperture radar data from space shows ground surface changes from before and after a major event like an earthquake. In this case, it is being used to show the devastating result of an explosion.

On the map, dark red pixels—like those present at and around the Port of Beirut—represent the most severe damage. Areas in orange are moderately damaged and areas in yellow are likely to have sustained somewhat less damage. Each colored pixel represents an area of 30 meters (33 yards).

The map is based on data from the European Space Agency’s Copernicus Sentinel program, and was analyzed by NASA’s Advanced Rapid Imaging and Analysis team and the Earth Observatory of Singapore.

Himalayan Ice Loss Measured with Cold War Spy Photos

Published on by Jonathan Crowe

nepal-sikkim in 1975 by glaciers on Sketchfab

Satellite imagery only goes back so far. To measure the rate of ice loss across the Himalayan glaciers, researchers turned to recently declassified spy satellite photos from 1975. The photos were used to create a digital elevation model (above) which was compared with more recent data. They concluded that the rate of ice loss was accelerating: it was twice as much from 2000 to 2016 than it was from 1975 to 2000. Columbia University, Science News. [Geography Realm]

Satellite Mode, Aerial Mode, Bird Mode

Published on by Jonathan Crowe

A lot of what we refer to on online maps as “satellite imagery” actually isn’t: the high-resolution stuff is usually taken from airplanes. This can be a point of confusion for some—and, according to this Twitter thread from Google Maps co-creator Bret Taylor, also a point of contention for the Google Maps team before it launched. Some engineers felt that calling the layer “Satellite” was factually incorrect—because of that aerial imagery—and therefore shouldn’t be used; others argued for “Satellite” based on label size and usability studies. It nearly got called “Bird Mode” as a compromise. [Boing Boing]

Satellite Image Guide for Journalists and Media

Published on by Jonathan Crowe

Pierre Markuse’s Satellite Image Guide for Journalists and Media:

So you would like to use a satellite image in your article and you would like to explain it to your viewers? Here is a short guide covering some of the most frequently asked questions and giving some general explanations on satellite images. It by no means covers all aspects, as there are far too many types of satellite images, but should give you a good start to find out more on your own and maybe motivate you to create your own images, which has become quite easy and quick even with no prior knowledge of it.

Complete with examples of imagery, examples of how to use it properly, and links to resources.

California Wildfire Roundup

Published on by Jonathan Crowe
San Francisco Chronicle (screenshot)

The San Francisco Chronicle’s 2018 California Fire Tracker is an interactive map of ongoing and contained wildfires—notably, at this moment, the Camp and Woolsey fires. It includes fire perimeter and air quality data. (Note: it’s glitchy on desktop Safari.)

Two Esri maps: a general wildfire map and a map of smoke from wildfires [Maps Mania]. Add to that a map of field damage reports in the area hit by the Camp Fire [Maps Mania].

NASA/JPL-Caltech

The Jet Propulsion Laboratory has produced a map of the damage from the Camp Fire based on satellite radar images. NASA Earth Observatory has maps and animations showing the impact of the Camp Fire on air quality and satellite images of the Woolsey Fire burn scar.

NOAA

The New York Times has a map tracking air quality in California. Smoke from the fires has reached the east coast: an outcome predicted by atmospheric models (see above map).

This interactive map from NBC News that superimposes the Camp Fire on any location to help people outside California get a sense of how big these fires are. [Maps Mania]

Mapping the Sulawesi Earthquake and Tsunami

Published on by Jonathan Crowe
The New York Times (detail)

Last week a magnitude-7.5 earthquake struck the Indonesian island of Sulawesi, triggering a tsunami that struck the city of Palu with far more force than expected. The New York Times has multiple maps and aerial images of the damaged areas; NASA Earth Observatory has before-and-after Landsat imagery.

The Changing Padma River

Published on by Jonathan Crowe
Padma River erosion animation
NASA Earth Observatory

Landsat observations have charted the erosion of the banks of the ever-changing Padma River, a major distributary of the Ganges in Bangladesh. This is vividly shown in this animation produced by NASA Earth Observatory, which “shows 14 false-color images of the Padma river between 1988 and 2018 taken by the Landsat 5 and 8 satellites. All of the images include a combination of shortwave infrared, near infrared, and visible light to highlight differences between land and water.” More on the erosion of the Padma River here.

Mapping the Northern California Wildfires

Published on by Jonathan Crowe
Washington Post (screenshot)

The Washington Post maps the largest of the wildfires burning in northern California: the Carr Fire threatening the city of Redding and surrounding communities. The Redding Record Searchlight has drone footage of the destruction wreaked by the Carr Fire in Shasta County. NASA has natural and false-colour imagery (Earth Observatory, Visible Earth) of the Carr Fire, as well as the Ranch and River Fires to the south, the so-called Mendocino Complex. See the Mercury News’s fire map of the Mendocino Complex, whose two fires’ combined acreage is now larger than the Carr Fire. Meanwhile, German astronaut Alexander Gerst observed the California wildfires from the International Space Station. [San Francisco Chronicle]