# Aitoff

## Description

The Aitoff projection is a modified azimuthal projection. It is a compromise projection whose graticule takes the form of an ellipse. This projection is appropriate for small-scale mapping of the world. It was developed by Russian cartographer David A. Aitoff in 1889.

The Aitoff projection is available in ArcGIS Pro 1.0 and later and in ArcGIS Desktop 8.0 and later.

## Projection properties

The subsections below describe the Aitoff projection properties.

### Graticule

The meridians are equally spaced and concave toward the central meridian. The central meridian is a straight line and half the length of the equator. The parallels are equally spaced curves, concave toward the poles. The projection outline forms a shape of an ellipse. The poles are presented as points, and they are co-vertices of the ellipse (located on the minor axis). The graticule is symmetric across the equator and the central meridian.

### Distortion

The Aitoff projection is neither conformal nor equal-area. That means that shapes, areas, distances, directions, and angles are all somewhat distorted. Scale is correct along the equator and the central meridian. Distortion values are symmetric across the equator and the central meridian.

## Usage

The projection is appropriate for small-scale mapping not requiring accurate area measurements.

## Limitations

The Aitoff projection is supported on spheres only. For an ellipsoid, the semimajor axis is used for the radius.

## Parameters

Aitoff parameters are as follows:

• False Easting
• False Northing
• Central Meridian

## Sources

Snyder, J. P. (1993). Flattening the Earth. Two Thousand Years of Map Projections. Chicago and London: University of Chicago Press.

Snyder, J. P. and Voxland, P. M. (1989). An Album of Map Projections. U.S. Geological Survey Professional Paper 1453. Washington, DC: United States Government Printing Office.