GPS Map Projections: Understanding 2D Distortion

What GPS Map Projections Are

Map projections are mathematical methods used to represent a three-dimensional Earth surface on a two-dimensional plane. These projections are essential for creating maps that can be easily read and understood by humans.

Different map projections have varying properties, such as preserving angles (conformal), areas (equiareal), or distances (equidistant).

Why Tissot’s Ellipses Matter

Tissot’s ellipses are a powerful tool for visualizing the distortion of map projections. By plotting these ellipses at various points on a map, one can observe how shapes and sizes change under different projections.

Each ellipse represents the local deformation of a small circle on the Earth's surface when projected onto the plane.

How Map Projections Distort 2D Space

Map projections inherently introduce distortions because they cannot perfectly represent all properties (area, shape, direction, and distance) simultaneously. These distortions are particularly noticeable in regions far from the projection's central meridian or center latitude.

The Tissot’s ellipses help identify these distortions by showing how circles on the Earth become distorted into ellipses under different projections.

Real-World Applications of Map Projections

Map projections are crucial in various fields, including navigation, cartography, and geographic information systems (GIS). They enable accurate representation and analysis of spatial data.

For example, the Mercator projection is widely used for nautical charts due to its property of preserving angles, but it distorts areas near the poles significantly.

Frequently asked questions

Try it live

Everything above runs in your browser — open GPS Map Projections: 2D Distortion Explorer and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.