# Quartic Authalic

## Description

This pseudo cylindrical equal-area projection is primarily used for thematic maps of the world.

## Projection method

Pseudo cylindrical equal-area projection.

## Lines of contact

Many lines; all parallels of latitude in the projection.

## Linear graticules

The central meridian is a straight line 0.45 times the length of the equator. Meridians are equally spaced curves. Parallels are unequally spaced, straight parallel lines perpendicular to the central meridian. Their spacing decreases gradually as they move away from the equator.

## Properties

### Shape

Generally distorted.

### Area

Equal area.

### Direction

Direction is generally distorted.

###
**Distance**

Scale is true along the equator. Scale is also constant along any given latitude and is symmetrical around the equator.

## Limitations

Useful only as a world map.

## Uses and applications

Thematic world maps. The McBryde–Thomas flat-polar quartic projection is based on this projection.

Learn more about the McBryde-Thomas flat-polar quartic projection

## Parameters

### Desktop

- False Easting
- False Northing
- Central Meridian

Supported on spheres only.