Cylindrical Equal Area Projection
Aug 27,2026

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Introduction

Cylindrical Equal Area Projection, also commonly known as the Lambert Cylindrical Equal Area Projection, is a type of cylindrical projection that preserves area. It was proposed in 1772 by the Swiss mathematician Johann H. Lambert. This projection maps the Earth's meridians and parallels onto a cylindrical surface, which is then unrolled into a plane. Meridians appear as equally spaced, parallel vertical lines, while parallels are horizontal straight lines perpendicular to the meridians. The spacing between parallels decreases toward the poles, and the poles are projected as straight lines with the same length as the Equator. This projection strictly ensures that relative areas on the map are consistent with those on the ground, but shape and angle distortion increase significantly with latitude. It is more suitable for large-scale mapping near the Equator and is often used in scenarios requiring precise area comparisons, such as climate maps and population distribution maps.

Projection Basic

The most common normal aspect of the Cylindrical Equal Area Projection places the cylinder tangent to the Equator. It strictly adheres to the equal-area condition, projecting the spherical graticule onto the cylinder, which is then cut along a generatrix and unrolled into a plane. During projection, the width of any infinitesimal area on the sphere is enlarged by a factor of 1/cos φ, while its height is correspondingly reduced by cos φ, ensuring that the area remains exactly equal before and after projection. The final result is a planar grid structure where meridians are equally spaced parallel straight lines and parallels are straight lines perpendicular to the meridians.

Pros

Equal-area property: The area of any region on the map is exactly consistent with that on the ground, facilitating accurate area comparisons and statistical analysis.
Suitable for thematic mapping: Highly suitable for thematic maps that require precise area representation, such as population density, land use, and climate distribution.
Regular grid: The graticule consists of orthogonal parallel straight lines, with a simple structure that facilitates map overlay and coordinate calculations.
Low-latitude shape preservation: Shape distortion is relatively small near the Equator, and surface features are better preserved.

Cons

High-latitude distortion: Shape distortion increases sharply with latitude, and features in high-latitude regions are severely stretched horizontally.
Angle distortion: Significant distortion in angles and directions makes it unsuitable for nautical navigation requiring precise bearing.
Narrow applicability: Good geometric accuracy is maintained only in narrow areas near the Equator or standard parallels.
Visual distortion: High-latitude regions appear extremely elongated and flattened, lacking intuitive geographic recognition.

Application Scenario

The Cylindrical Equal Area Projection, with its strict preservation of area, is widely used in thematic map production requiring accurate representation of regional area proportions, such as global or regional population density maps, land use and agricultural cover maps, climate zone and vegetation classification maps, and resource reserve and economic statistics maps. It performs particularly well in tropical and low-latitude regions near the Equator, making it also commonly used for national-level statistical maps in regions such as Africa, South America, and Southeast Asia. In addition, its regular grid structure makes it convenient for area overlay and comparative analysis in GIS spatial analysis and remote sensing data processing.