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Equal-area maps take a different approach and distort the shape of the features in order to retain their size relative to one another. Conformal maps retain the true local shape of the features being depicted but distort their size. This distortion can affect the size and/or shape of the areas being depicted.

To avoid creating a fragmented map cut into such small sections that nothing is connected, Earth’s surface must be stretched or distorted in order to flatten it into the form of a map. If you have ever tried to remove an orange peel in one piece, you know that you cannot make something round completely flat without cutting or stretching it. In other words, elevation, or height is ignored, and the surface of Earth is modeled by an ellipsoid that is then projected onto a flat surface. While we know that the Earth is a smooth ellipsoid shape, a datum, an ellipsoid model tied to the earth at a specific location, works well to map the two-dimensional coordinates of the Earth. Approximating Earth’s Shape and Flattening itĪ calculated ellipsoid model of the Earth is used to approximate the shape of the planet. However, since all maps use some form of projection to compress and stretch the Earth onto a flat surface, the geodesy behind projections and the impacts of different projection methods should be considered when creating any map. Being a complex science, geodetics is often overlooked by GIS practitioners when creating a map. Geodesy is the study and mathematics behind the modeling of Earth.

Luckily, Global Mapper and Geographic Calculator from Blue Marble Geographics can help you manage the geodetic characteristics and projection for any GIS or mapping project.

Hopefully, the fact that the Earth is not flat is not news to you, but it is an important fact to consider when mapping and modeling any area on Earth. Earth is a geoid, an irregular and lumpy, roughly ellipsoidal shape that is difficult to map and model in its entirety. Globes portray the Earth in a spherical model, but in reality, Earth is not exactly a sphere either. A commonly accepted fact is that the Earth is not flat.