From the course: Real-World GIS (2014)

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Using geoids, spheroids, and datums

Using geoids, spheroids, and datums - ArcGIS Tutorial

From the course: Real-World GIS (2014)

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Using geoids, spheroids, and datums

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Now let's explore the concept Geoids, Spheroids, and Datums. The earth is irregular in shape because of its rotation and its geology. The surface of the Earth undulations, that cause it to be quite irregular even though it's round in shape. Geodetic scientists have tried to model the surface of the earth and they have created the Geoid, which is an irregular-oval or egg-shaped surface that tries to approximate the surface of the earth. The Geoid offers a nice smoother surface to work with, when trying to model the earth. But because of its irregular shape, it also is difficult to use in mathematical sense for modeling the earth. Therefore, geodetic scientists have used the Ellipsoid to approximate the Geoid. So, the Ellipsoid approximates the Geoid which approximates the surface of the earth. The Ellipsoid is a very easy model to use, to model the curvature of the earth. And this can be done very easily using the concept of the semi-major axis and the semi-minor axis. If we adjust…

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