<P> Three dimensional modeling of loudspeaker output patterns can be used to predict their performance . A number of polar plots are required, taken at a wide selection of frequencies, as the pattern changes greatly with frequency . Polar plots help to show that many loudspeakers tend toward omnidirectionality at lower frequencies . </P> <P> The spherical coordinate system is also commonly used in 3D game development to rotate the camera around the player's position . </P> <P> To a first approximation, the geographic coordinate system uses elevation angle (latitude) in degrees north of the equator plane, in the range − 90 ° ≤ φ ≤ 90 °, instead of inclination . Latitude is either geocentric latitude, measured at the Earth's center and designated variously by ψ, q, φ ′, φ, φ or geodetic latitude, measured by the observer's local vertical, and commonly designated φ . The azimuth angle (longitude), commonly denoted by λ, is measured in degrees east or west from some conventional reference meridian (most commonly the IERS Reference Meridian), so its domain is − 180 ° ≤ λ ≤ 180 ° . For positions on the Earth or other solid celestial body, the reference plane is usually taken to be the plane perpendicular to the axis of rotation . </P> <P> The polar angle, which is 90 ° minus the latitude and ranges from 0 to 180 °, is called colatitude in geography . </P>

At what point on or inside the earth are longitude and latitude angles measured
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