# McBryde-Thomas Flat-Polar Quartic

## Description

This equal-area projection is primarily used for world maps.

## Projection method

A pseudo cylindrical equal-area projection in which all parallels are straight lines and all meridians, except the straight central meridian, are equally spaced, fourth-order (quartic) curves.

## Linear graticules

All parallels are unequally spaced straight lines that are closer together at the poles. The poles are straight lines one-third as long as the equator. The central meridian is a straight line 0.45 times as long as the equator.

## Properties

### Shape

Shapes are stretched north–south along the equator, relative to the east–west dimension. This stretching decreases to zero at 33°45' N and S at the central meridian. Nearer the poles, features are compressed in the north–south direction.

### Area

Equal area.

### Direction

Distorted except at the intersection of 33°45' N and S and the central meridian.

### Distance

Scale is distorted everywhere except along 33°45' N and S.

## Limitations

Useful only as a world map.

## Uses and applications

Thematic maps of the world.

## Parameters

### Desktop

- False Easting
- False Northing
- Central Meridian

Supported on spheres only.

geographic_coordinate_systems.pdf | A geographic coordinate systems pdf file which contains lists of supported gcs and vcs. |

projected_coordinate_systems.pdf | A projected coordinate systems pdf file which contains lists of supported pcs. |

geographic_transformations.pdf | A geographic transformations pdf file which contains lists of supported geographic and vertical transformations. |

### Workstation

- Longitude of projection's center

Supported on spheres only.

geographic_coordinate_systems.pdf | A geographic coordinate systems pdf file which contains lists of supported gcs and vcs. |

projected_coordinate_systems.pdf | A projected coordinate systems pdf file which contains lists of supported pcs. |

geographic_transformations.pdf | A geographic transformations pdf file which contains lists of supported geographic and vertical transformations. |