Maps and routing: a glossary

Jeff Vasishta Oct 15, 2021 · 9 min read

While much of EV terminology seems as strange and daunting as hieroglyphic markings on ancient cave walls, you’ll be relieved to know that navigation still relies on good old maps. Here’s a glossary to help you dive in, or fill the gaps!


No prizes for guessing that an altimeter is used to mention altitude, i.e. distance of a point above sea level. Knowing your altitude is essential if you’re climbing Everest or coming in to land at Heathrow. But it’s also important information when routing electric vehicles!

Firstly, a bit about altimeters and how they work. Frenchman Louis Paul Cailletet invented the first altimeter sometime around the turn of the century (last century not this one). American Lloyd Espensceid invented the radio altimeter, which measures the distance between an aircraft and the ground below it in 1924, though they weren’t sold until 1937. The first barometric altimeter, which measures altitude by calculating air pressure around it, was invented in 1928 by German-born American Paul Kollsman.

Types of Alimeter

Barometric altimeters have been widely used for the best part of a century. At its most basic, it includes a sealed metal chamber, a spring, and of course, a pointer indicating meters or feet. It works by the chamber expanding as air pressure decreases, and contracting as it increases. This forces the spring to bend and thus move the pointer. Because of its simplicity, it can be used equally by aircraft and mountaineers alike.

A radar altimeter calculates the height of a plane above ground by measuring the time for an electromagnetic pulse to travel from the aircraft to the ground and back.

Electrically powered GPS altimeters are used in conjunction with an EV’s navigation system and they are essential for judging battery usage when ascending and brake-powered recharging when descending.


The ancient science of making maps and charts. Loosely speaking the term doesn’t just refer to the actual finished map, but all the steps involved in producing the map. This includes the planning, aerial photography, field surveys, etc up to the final printing. However, mapmakers often leave out the early stages of map-making and refer to cartography as the editing and printing process.


Elevation is a fairly broad, catch-all term that can be used to measure the distance of something above a fixed reference point — usually sea level or the horizon. While elevation and altitude are often used fairly interchangeably, the main difference between them is that altitude is used to describe the vertical distance between an object and reference point as opposed to the height above sea level in the case of elevation.


Global Positioning System. There was a time when the term GPS was only used by people involved in America’s space program or the military. These days it’s as common in an average everyday car as an airbag or automatic window.

The Global Positioning System is a satellite-based radio navigation system owned by the US government and operated by the US Space force. It allows anyone on or near earth with a receiver to receive geolocation - providing there’s an unobstructed line of sight to four or more GPS satellites.

The GPS project was started by the US Department of Defence in 1973 and the first full constellation of 24 satellites became operational in 1993. A receiver measures just over 1.5 square cm (or slightly more than half a square inch) in size and its use is extensive. These days GPS receivers are used in conjunction with cartography to allow drivers to navigate.


Otherwise known as the GPS Exchange Format, this is an XML schema (used to describe and validate XML data — data that can be read by both humans and machines. It’s somewhat similar to HTML which describes a website’s structure, displaying information). It’s essential for navigation as it can be used to describe waypoints, tracks, and routes.


If you’ve ever wondered how certain locations can be placed on a map with pinpoint accuracy, the answer is a grid, also known as a grid reference system, grid reference, or grid system. It’s the same idea that you learned back in geography class in school. It defines locations in maps using Cartesian coordinates based on a specific map projection. Numbered lines provide the reference for a location on a map using easting and northing coordinates.


We often take maps for granted. These drawings of the earth’s surface, showing all or some of the earth including different regions, countries, as well as natural features such as rivers and mountains and man-made ones like roads and bridges, are constantly being modified. They are as essential for vehicle navigation today as they were for navigating the globe by ship hundreds of years ago.

Mercator Projection

Named after Flemish cartographer, Gerardus Mercator, way back in 1569, The Mercator Projection represents the earth as an ellipsoid on a flat rectangular surface (a map). This is achieved by distorting the size of sections of the globe the further you get from the equator, making the North and South Poles the most distorted. Thus, on Mercator’s maps — Greenland appears to be the same size as Africa, whereas in reality, Africa is 14 times larger.


This is the study of forms and features, both natural and artificial, that appear on land surfaces. Generally speaking, the topography of an area is often thought to be the relief or terrain of an area and is depicted on most maps with elevation contours. In addition, topographic maps also have hypsometric tints and relief shading.


No, not the same thing that you use to cover the floors in your bathroom, unless you factor in that both consist of squares over a flat surface. A map tile is a map that’s divided into a series of squares arranged in a grid. When the map moves to a new location it calculated which tiles are being utilized and translates the specific information from that tile for use. This allows limited data usage. It also allows zooming in for more detail. At zoom level 0, the entire world appears on a single tile. The magnification is increased by a factor of 2 with each zoom level. So, at zoom level 1 a map will appear as a grid of 2x2 tiles, at zoom level 2 is will be 4x4, and so on.


AR Navigation

Augmented Reality navigation is already being used in Teslas and it’s only a matter of time before it becomes widely used as a navigation means in all cars. The use of cameras along with computer-generated perceptual information means that objects not shown on standard GPS navigation systems such as pedestrians, road closings can make for a visually enhanced driving experience. Adding the data used to create and display AR objects such as latitude, longitude, elevation, pitch, roll, and yaw creates a three-dimensional movement of an object. This can then be used to determine camera positioning in real-time as movement is occurring to increase accuracy.

AR’s capabilities are immense. Working in conjunction with satellite imagery it will be possible to determine if parking spaces are available before you arrive at the location and have a more immersive experience displayed on the windscreen as you drive, without the use of another separate screen.


The process of converting addresses (like a street address) into geographic coordinates (like latitude and longitude), which you can use to place markers on a map, or position the map.


An isochrone map is a map that depicts the area accessible from one point within a certain time. In short, it allows drivers to know, via their navigation system, how long it will take them to travel from point A to point B. The navigation maps on our phones also have isochrone maps showing the time it will take to travel via foot, car, bicycle, or public transport. Before they were digitized in cars, isochrone maps were drawn up for use by public transport.

Car Navigation

Car navigation systems are standard in all vehicles and most phones now. They generally rely on GPS (Global Positioning System), using radio signals from satellites that send their position and the time of transmission. The GPS receiver in the car catches the signal, calculating the time, and is then able to calculate the distance from the satellite. GPS systems need to cross-reference between four satellites to accurately calculate your car’s position and predict the route and distance to your desired location which is shown on the digital maps in the GPS receiver.


OpenStreetMap is a community-driven open data platform that is formally operated by the OpenStreetMap Foundation. Contributors include enthusiast mappers, GIS professionals, engineers running the OSM servers as well as humanitarians mapping disaster-affected areas amongst many others. They contribute data about everything from roads to trails to restaurants, public transport hubs, etc., throughout the world. Its use in cars is paramount for finding specific locations not available in standard navigation systems.


Point of Interest. These can be anything from supermarkets to tourist attractions to gas stations. This function has been a staple on car navigation systems for many years.

Routing Engine

With a routing engine, we indicate all the different software, algorithms, and data lakes that together allow for routes to be computed. If you read EV routing engine, that means the routing engine is designed specifically for Electric Vehicles, like Chargetrip’s one.

Route map

A route map is a transportation map. It shows the main roads in a particular area including the main routes used by buses, trains and all forms of transport in a certain area.

Telemetry data

According to Wikipedia telemetry is the collection of measurements or other data at remote or inaccessible points and their automatic transmission to receiving equipment for monitoring. Telemetry can be relayed using radio, infrared, ultrasound, GSM, satellite, or cable.

Generally speaking telemetry works via sensors that measure physical data (rainfall, air pressure, or temperature). Once the data is converted into electrical voltages it can be combined with timing data and transmitted. It’s useful for mapping in creating accurate actionable analytics such as weather and climate reports or user interaction with a specific app.

Telematics data

Telematics data is the technology used to monitor information relating to a single vehicle or an entire fleet of them. This data can be collected using GPS, sensors, and vehicle engine data and includes everything from vehicle location, driver behaviour, engine diagnostics, and vehicle activity. It’s then possible to see this data visually on software platforms which helps fleet or vehicle operations departments manage their resources effectively.

Turn-by-turn navigation

This is probably the most regularly used feature of a GPS navigation system where directions to a destination via a selected route are presented to the user in both visual and spoken instructions.