State Plane Coordinate System State Plane Coordinate System The State Plane Coordinate System (SPS or SPCS) is a set of 124 geographic zones or coordinate systems designed for specific regions of the United States. Each state contains one or more state plane zones, the boundaries of which usually follow county lines. There are 110 zones in the contiguous US, with 10 more in Alaska, 5 in Hawaii, and one for Puerto Rico and US Virgin Islands. The system is widely used for geographic data by state and local governments. Its popularity is due to at least two factors. First, it uses a simple Cartesian
Tilted plane focus the distance between lens and the sensor or film plane, focus in the space in front of the camera is not on a point but rather on a plane parallel to the film plane. Spherical construction of lenses, rather than the ideal parabolic construction which is rarely and expensively achieved, means that this plane is slightly concave—more so in simple single element lenses and increasingly so with lenses of lower quality construction and materials. Compound lenses are built to correct this "spherical aberration" or "curvature of field". Varying the distance between the lens and sensor or film plane across the