If the road grid in online maps of China doesn’t line up with the aerial/satellite imagery layer, Anastasia Bizyayeva explains in a Medium post earlier this year, it’s because China’s map data uses a different geodetic datum, GCJ-02, rather than WGS-84. “GCJ-02 is based on WGS-84, but with a deliberate obfuscation algorithm applied to it. The effect of this is that there are random offsets added to both latitude and longitude, ranging from as little as 50m to as much as 500m.” Chinese map companies are obliged to use GCJ-02 so their maps and imagery line up; outside China, companies can choose to use Chinese data and imagery and have alignment artifacts at the Chinese border, or use Chinese data with images aligned with WGS-84 and have the roads appear offset from the imagery. [Kottke]
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Atlas of Ungulate Migration

The U.N. has launched an online Atlas of Ungulate Migration. “Driven by tracking data on ungulate migrations, the Atlas of Ungulate Migration serves as a repository for up-to-date migration maps that can inform conservation planning, infrastructure development and policy making. The maps detail high, medium and low-use migration corridors for a diversity of species, ranging from the iconic Serengeti wildebeest and African elephant, to the saiga of the Central Asian steppe. Most importantly, the maps illustrate where critical migration routes intersect with linear barriers like roads or railways. This atlas represents the best available science for extant migrations, with downloadable maps each accompanied by a factsheet describing the migration in detail, the data analysis, and its specific threats. The atlas is living, and continually updated.” News release.
Two Map Books from the Bodleian

Some coverage of two map books published earlier this year by Bodleian Library. First, Atlas Obscura interviews Kris Butler, whose Drink Maps in Victorian Britain looks at how the temperance movement used maps to fight excessive alcohol consumption. They were, apparently, directly inspired by John Snow’s cholera map. From the interview:
Drink maps were specific to targeting the U.K. magistrates, to try to get these lawmakers to stop granting licenses. So it had a really specific legislative, regulatory goal. […] In one case [in 1882, in the borough of Over Darwen in Lancashire, England], after looking at a drink map, the magistrates decided to close half of the places to buy alcohol. Their rationale was, even if we close half of these, you still don’t have to walk more than two minutes to buy another beer, which I just think is the most beautiful rationale I’ve ever read. It was challenged, and it held up on appeal.
Meanwhile, the Bodleian’s own Map Room Blog (no relation) points to Debbie Hall’s Adventures in Maps, a book about maps and travel and exploration. From the book listing: “The twenty intriguing journeys and routes featured in this book range from distances of a few miles to great adventures across land, sea, air and space. Some describe the route that a traveller followed, some are the results of exploration and others were made to show future travellers the way to go, accompanied by useful and sometimes very beautiful maps.” I reviewed Debbie Hall’s Treasures from the Map Room (also no relation) in 2016.
Adventures in Maps by Debbie Hall: Amazon (Canada, UK) | Bookshop
Drink Maps in Victorian Britain by Kris Butler: Amazon (Canada, UK) | Bookshop
See also: Map Books of 2024.
New Leventhal Exhibition: Processing Place
An exhibition exploring the history of computerized mapping, GIS and remote sensing opened at the Boston Public Library’s Leventhal Map Center last Friday. Processing Place: How Computers and Cartographers Redrew our World runs until March 2025.
In the long history of mapmaking, computers are a relatively new development. In some ways, computers have fundamentally changed how cartographers create, interpret, and share spatial data; in others, they simply mark a new chapter in how people have always processed the world. This exhibition features objects from the Leventhal Center’s unique collections in the history of digital mapping to explore how computers and cartographers changed one another, particularly since the 1960s. By comparing maps made with computers to those made before and without them, the exhibition invites us to recognize the impacts of digital mapping for environmental management, law and policy, navigation, national defense, social change, and much more. Visitors will be encouraged to consider how their own understanding of geography might be translated into the encodings and digital representations that are essential to processing place with a computer.
The online version of the exhibition is here.
Thematic Mapping and the 2024 U.K. Election

There’s more than one way to depict data on a map. At the last Esri user conference, Sarah Bell, Kenneth Field and John Nelson demonstrated different ways to map the results of the last U.K. parliamentary election, and how they changed from the previous election. The video of their presentation is attendee-only, but Ken and John have posted about how they each went about their tasks: here’s Ken’s post and here’s John’s; plus, as is his wont, John has posted a video.
A Look Back at the SRTM
Last month NASA Earth Observatory ran a two-part series about the Shuttle Radar Topography Mission, which produced a high-resolution digital elevation model of the Earth based on radar data collected by the shuttle Endeavour in 2000. The first part looks at how Endeavour gathered the data, the second part at how it’s been used.
Nearly a quarter century after the mission to map the world, the SRTM’s data still yields results. Just this year, it aided in wildfire forecasting for Iran’s Zagros Mountains, tracking soil erosion in South Africa, assessing flood risk on the coast of Brazil, and even determining how the locations of power-generating wind turbines affect real estate values. Tens of thousands of research papers are published every year that rely on SRTM maps for these and other environmental, economic, agricultural, and public safety studies.
The Map Men on Gerrymandering
The Map Men look at gerrymandering on U.S. electoral district maps. A reasonably comprehensive primer on the subject even if comes from a couple of Brits baffled by the subject. And they finish with a surprisingly sharp point: gerrymanderers wouldn’t know how to draw maps like these if voting intentions weren’t predictable.
Online Maps Roundup: August 2024
Apple Maps has launched real-time transit information for Tokyo. Meanwhile, MacRumors takes a look at what’s coming to Apple Maps in iOS 18, with an additional look at the upcoming “search here” function. Google and Waze updates announced at the end of the last month: Google Maps gets easier incident reporting and destination guidance (the building you’re heading to is highlighted on the map); Waze upgrades include new camera alerts, event-based (e.g. concerts and sporting events) traffic notification and reporting, and locked-screen navigation. Also, the Google Maps app now has a simplified tab bar. And they’ve changed the pin design too. What can I say: updates are a little less earth-shattering than they used to be.
A History of the Harvard University Institute of Geographical Exploration
“The Harvard University Institute of Geographical Exploration was one of the first and most well-wrought private institutions in aerial photography in the first half of the 20th century. Its short institutional life at Harvard was replete with materials, stories and scandal, and its pieces remain scattered today throughout the Harvard Archives and Libraries system and beyond.” Ana Luiza Nicolae tracks down what records, photos and other materials can still be found on the Harvard campus that once belonged to Alexander H. Rice’s HUIGE, which was not closely affiliated with Harvard’s geography department but was shut down at roughly the same time.
Multispectral Analysis Reveals Lost Details on a 16th-Century Portolan Chart

The Library of Congress reports on how its Preservation Research and Testing Division used multispectral imaging to bring out previously illegible place names on a 16th-century portolan chart of the east coast of North America. Initially the PRTD was brought in to confirm that the chart was legit before the Library purchased it (which it did last fall), but the faded iron gall ink in some areas of the map suggested obscured details that further analysis could draw out and place names that could be made legible again. According to the article, this represents the first time the Library has posted an enhanced image of one of their holdings.
‘An Impossibly Heavy, Large Silver Globe’
“Of all the globes in the Geography & Map Division’s collections, there is one that has always caught my eye: an impossibly heavy, large silver globe tucked away in our stacks, that stands without any depiction of the earth’s physical features at all. The large silver orb instead displays only a coordinate system grid composed of unlabeled latitude and longitude lines.” Meagan Snow writes about the unlikeliest of globes in the Library of Congress’s collection: a precisely machined 34-inch blank metal globe. What on earth it was it used for? Answer unclear: “The intended use of the globe is described as ‘for earth study.’”
Geofence Warrants Found Unconstitutional by One U.S. Federal Court
A U.S. federal court has held that geofence warrants are unconstitutional under the Fourth Amendment, finding that they fit the definition of general warrants that are “categorically prohibited” by that Amendment. EFF, TechCrunch. Geofence warrants, you may recall, require a data provider (usually Google) to identify all users in a given area during a given time period. While ruling them unconstitutional, the U.S. Fifth Circuit Court of Appeal nonetheless allowed evidence collected under a geofence warrant in the case under consideration, citing the good-faith exception, given the novelty of such warrants at the time and the lack of legal guidance available to law enforcement: see the court’s decision.
Geofence warrants are now in something of a grey area: the Fourth Circuit upheld geofence warrants’ legality, at least under certain circumstances, only last month. The two cases may not be an apples-to-apples comparison, but even so the constitutionality of location data searches may take a while (and the Supreme Court, eventually) to sort out.
OpenStreetMap Is 20 Years Old
OpenStreetMap is celebrating its 20th anniversary today. It was originally created in response to restrictive Ordnance Survey licensing in the U.K., in a context that seems unrecognizable today. Founder Steve Coast writes about the anniversary (mirror link). “Allowing volunteers to edit a map in 2004 was simply anathema and bordering on unthinkable. Map data was supposed to be controlled, authorized and carefully managed by a priesthood of managers.”
Tim Walz Is a Huge GIS Nerd
Yesterday, U.S. Vice President and Democratic presidential nominee Kamala Harris announced Minnesota Governor Tim Walz as her running mate. Among other things, Walz is a former social studies teacher and early adopter of GIS as a teaching tool, and has nerded out on geography and GIS throughout his political career, both in the U.S. House of Representatives and as governor. Walz even spoke at the 2024 Esri User Conference in San Diego last month (as someone married to a high school teacher, I can say this: he totally talks like a high school teacher). See also this summary of the talk, and Walz’s map nerdery in general, in the Minnesota Reformer.
The Babylonian Map of the World
The British Museum has posted this video about the Babylonian Map of the World, a nearly 3,000-year-old clay tablet inscribed with Akkadian script and a schematic map that is often called the oldest map in the world. The video, part of the Museum’s Curator’s Corner series, focuses on the discovery in 1995 of a missing section of the tablet, and what the inscriptions mean. Here’s the Museum’s collection listing for the tablet.
Previously: An Ancient Map of the Mesopotamian World.