Polyconic
| Name | Polyconic |
| Model | Conic |
| Type | n/a |
| Meridians | Complex curves concave toward a straight central meridian |
| Parallels | Non-concentric circles except for a straight equator |
| Spacing Meridian | Equal and decreases toward the poles Graticule spacing compromises all properties |
| Spacing Parallels | Spaced true to scale on central meridian Spacing increases toward the east and west |
| Linear Scale | True along each parallel and along central meridian 7% maximum scale error on U.S. |
| Specialties | Where other conic definitions are based on a cone of 1 or two tangency parallels, Polyconic is based on an infinite number of cones with an infinite number of tangency parallels Area is deformed (i.e., not equal area) Angle is deformed (i.e., not conformal) |
| Uses | Area of interest has a predominantly North-South extent Mosaicking is limited |
| Example |
