Open Earth Articles

The question arrives late, and it always arrives from the same place. A customer's legal team asks which licences apply to the data behind a product, whether any of them require the customer to open t...

Attribution is the cheapest obligation in open data licensing. It requires no source disclosure, no share alike propagation, and no legal review of a derived work. It asks for a credit line. It is als...

A dataset lists its date as last month. The map renders, the features look plausible, and a team builds an analysis on it. Somewhere in that dataset are buildings surveyed six years ago, roads last ve...

A building footprint has an area of 412.7364 square metres. A point of interest sits at 106.8271943, minus 6.1753621. A pipeline reports a road segment as 1,847.23 metres long. Every one of those figu...

A query returns an empty array. No hospitals inside the polygon, no pharmacies on the street, no buildings in the block. The response came back fast, the status code was 200, and nothing about it rese...

Every spatial dataset is incomplete. That much is uncontroversial and mostly harmless, because analysts are used to reasoning about noise. The problem is that spatial incompleteness is not noise. It i...

Official economic statistics are excellent and they arrive with three constraints that limit what can be done with them. They are slow, often published quarterly or annually with a lag of months. They...

Density is the most quoted number in urban analysis and one of the least specified. A city described as dense might have crowded dwellings and low buildings, tall buildings and small households, or a ...

Insurance is one of the few industries that has been doing spatial risk assessment continuously for well over a century, long before there were geospatial APIs to do it with. The methods are old, the ...

A dispatcher looks at a map and sees a line between the depot and the drop point. The routing engine has already decided that line is the best one available: shortest, or fastest, or cheapest by whate...

Most spatial analysis is about finding things. Where are the clinics, which roads connect to the port, how many buildings sit inside the flood extent. Those questions are tractable because the evidenc...

Footfall data is sold, not published. Mobile location panels, card transaction panels and sensor networks all live behind commercial contracts, and for most teams the licence is either unaffordable or...

A public hazard feed publishes a flood alert. It carries a location, a severity class, a timestamp, and an affected area expressed as a rectangle. Within a few minutes it is possible to intersect that...

Site selection is usually presented as a ranking problem. Six candidate locations go in, a score comes out for each, and the highest number wins. That framing is convenient and it is also the reason m...

An agent queries a spatial API for the buildings inside a bounding box and receives an empty array. The status is 200, the response shape is valid, the list has zero elements. Every observable propert...

Every API that answers questions has to decide how much of its answer is machine readable. The two ends of the range are familiar. A strict schema gives fields with names and types, parseable without ...

An API endpoint has a price, and the price is not the number on the pricing page. For a human developer, a call costs some milliseconds and a fraction of a quota. For an agent, a call costs three thin...

Authentication systems were built on an assumption that has held for decades: behind every credential there is a person, or a service that a person configured and is responsible for. The API key in an...

Error handling was designed for two audiences, and neither of them is a language model. Status codes were written for a client library, which needs to know whether to raise. Error messages were writte...

A geospatial API has a peculiar traffic shape. Most of the surface of the planet is never requested at all. A small set of places, the centre of a capital city, the ports, the airports, the neighbourh...

A person reading a report about an unfamiliar place applies an enormous amount of unconscious filtering. A number that seems too round gets a second look. A figure for a remote area gets discounted be...

Rate limiting was designed against a mental model of a human at a keyboard, or a script written by someone who read the docs and set a delay. The traffic it now has to survive is generated by systems ...

An API that is only documented in prose is invisible to a machine. A human developer lands on a docs site, reads the overview, works out the auth model, finds the endpoint that looks relevant, and inf...

An API designed for humans has documentation, examples, a support channel, and a developer who will read three paragraphs to work out which endpoint to call. An API designed for an agent has one descr...

A spatial model that has never been checked against the world is a hypothesis with a user interface. It emits building heights, road widths, canopy cover, population estimates, and every one of those ...

A photograph of a street contains, in principle, a great deal of commercial information. The names of the businesses, what they sell, whether they look open, whether the frontage has been refitted rec...

Tree canopy is one of the few things a city can measure from above that maps directly onto how the place feels and functions. It cools streets, intercepts rainfall, shades buildings, and occasionally ...

The question that stops a delivery, a construction job, or a fire appliance is nearly always the same one: how wide is the street. Not how long, not what it is called, not what class it was assigned. ...

Every pipeline drawing on more than one source eventually has to decide whether two records describe the same thing. A building footprint from one provider and a footprint from another. A road from an...

A map tells you what is there. A change feed tells you what happened. The second is usually the more valuable product, and it is much harder to build honestly....

Photogrammetry recovers three-dimensional geometry from a set of overlapping photographs. Given enough images of the same object from enough positions, the shape of that object and the position of eve...

A photograph of a street and a photograph of a scale model of that street can be identical. No amount of processing applied to one image can tell the two apart, because the image is a projection and p...

Two systems can both claim to find buildings in aerial imagery and mean entirely different things by it. One returns rectangles that contain buildings. The other returns, for every pixel, whether that...

A footprint tells you how much ground a building covers. Almost every question anyone actually asks needs the third dimension: how much floor area is inside, how many people it can hold, how much of i...

A building footprint is a closed polygon drawn around the outline of a structure. It is the simplest object in applied geospatial work, and it is the one that most often ships wrong, because a footpri...

A live map of ships and aircraft is the most convincing thing in open geospatial data. Thousands of icons move in real time, each with an identity, a speed, a heading, a destination. It feels like wat...

Elevation data looks like the most solid ground in geospatial work. Terrain does not move much, the files are just grids of numbers, and every provider ships something global and free. That impression...

Night lights imagery is the most seductive dataset in open Earth observation. A single global composite shows coastlines picked out in white, dense corridors between cities, dark interiors, and it loo...

A global disaster alerting system exists because most disasters are reported slowly and unevenly. An earthquake is detected by seismic networks within minutes, but who was affected, and how badly, is ...

Most people meet free satellite imagery through a screenshot: a green field, a brown scar where a forest used to be, a city glowing in false color. The screenshot is the end of a long chain of decisio...

Open map data has never lacked sources. It has lacked a source that is simultaneously broad, conventionally structured, licence-clear, and shipped in a format that a production pipeline can consume wi...

OpenStreetMap is a global, openly licensed map database built by contributors. That description is accurate and hides everything a developer needs to know, because the interesting properties of OSM ar...

Vector geospatial data has a small vocabulary. A position, a sequence of positions, and an enclosed area. Everything else, every road network, cadastral map, flood extent, and points-of-interest datab...

A conventional join needs a shared key. Two tables both hold a customer identifier, the identifier matches or it does not, and the result is unambiguous. Spatial data usually has no such key. A datase...

An address is a human instruction. It tells a person how to reach a place using shared local knowledge: which town, which street, roughly how far along, which door. A coordinate is a machine instructi...

Every flat map of the Earth is wrong, and not because cartographers have not tried hard enough. The wrongness is mathematically necessary. A curved surface cannot be laid flat without stretching, tear...

Four numbers describe a rectangle: a minimum and maximum for each axis. That rectangle is the most common object in spatial computing. It is how nearly every API accepts an area of interest, how nearl...

A pair of numbers is not a location. It becomes a location only when something states what the numbers are measured against: which model of the Earth's shape, which origin, which units, and in which o...

There are only two ways to write the world into a file. Either the world is a set of discrete things that have coordinates, or it is a surface whose value can be sampled anywhere. Everything in geospa...

A latitude and longitude pair is one of the least informative facts a system can hold. It says where something sits in a reference frame. It says nothing about whether that location is inside a flood ...

Most people meet geographic data as a picture. You open a map, you look at it, and your eyes do the interpretation. A digital twin of Earth inverts that relationship. The picture becomes secondary and...

Almost every geospatial API opens with the same sequence. Create an account, confirm an email address, generate a key, read a quota table, and only then send the first request and find out whether the...

When people first connect a language model to external data they usually write glue: a function that builds a URL, parses a response, and hands the result back as text. It works, and it is exactly the...

Open is a word that survives contact with a procurement questionnaire badly. It gets applied to data usable for any purpose with no conditions, to data usable provided the source is credited, to data ...