Today, services like Google Maps rely on sophisticated imaging equipment from Earth Observation satellites. There are currently hundreds of Earth Observation satellites on orbit, each observing a small portion of Earth at a time. But how were maps created before satellites?
Historically, triangulation and surveying were the primary methods used to produce maps. Maps from Babylon times were made by measuring and surveying the positions of different objects on the surface of the Earth. The distances and angles between those points were calculated by using ropes, while the angles were measured using magnetic compasses. Magnifying glasses or small telescopes attached to compasses were also used.
Starting in the 15th century, explorers traversed the world creating maps of places they visited. As military initiatives became a part of exploration in the 16th century, the Ottoman cartographer Piri Reis created The Piri Reis map, a pre-modern world map. It was not until the 18th century that the modern mapping of countries began. This mapping was done primarily by building networks of trigonometry pillars across regions like the UK.
A theodolite, a measuring instrument, was used to calculate the angles between each pillar and the distance seen between them. This tool was used both on land and in the sea. While trigonometry pillars were phased out after the Global Positioning System (GPS) was launched in the 70s, theodolites are still used today alongside other devices. GPS still uses the same basic techniques of trigonometry to measure the earth's surface.
For generations, mapping was land oriented, before migrating to aerial and space-based mapping. As we have experienced tremendous advancements and cost reductions in the space industry in recent years, satellite imaging has become accessible to the private sector, not just governments. Satellite imaging startups like Planet Labs, Terra Bella and Astro Digital continue to disrupt the industry, making satellite imagery accessible to all.