Goode’s Homolosine Projection is a composite, equal-area map projection that minimizes distortions for global maps. The projection is named after John Paul Goode, an American geographer. It combines elements of two distinct map projections. The sinusoidal projection is used for equatorial regions, and the Mollweide projection is used for higher latitudes. This projection is particularly valuable for thematic and global distribution maps, where precise area representation is crucial.
Characteristics of Goode’s Homolosine Projection
1. Equal-Area Projection
The primary strength of the Goode’s Homolosine Projection is that it preserves the relative area of landmasses and oceans. This makes it ideal for representing global data like vegetation, climate zones, or population distribution. Unlike conformal projections, which preserve angles but distort areas, the Goode projection ensures that every region maintains its proportional size. It does not matter how large or small the region is. Conformal projections preserve angles but distort areas. The Goode projection ensures that every region, no matter how large or small, maintains its proportional size.
2. Interrupted Projection
The Goode Homolosine projection is often displayed in an interrupted form. This means that the map is cut into multiple lobes to reduce distortion. These interruptions usually occur over oceans, where accuracy is less critical, allowing the projection to reduce distortion of landmasses. The effect is a more natural representation of continents while sacrificing continuity in oceanic areas.
3. Combination of Two Projections
- Sinusoidal Projection: The sinusoidal projection is used in the equatorial regions between approximately 40°N and 40°S latitude. This projection is an equal-area projection. It minimizes distortion along the equator but introduces more distortion as one moves toward the poles.
- Mollweide Projection: The Mollweide projection, also an equal-area projection, is used for higher latitudes, including the poles. It excels at representing the polar regions with minimal distortion in area. Still, it distorts shapes more as it moves away from the poles.
By combining these two projections, Goode’s Homolosine Projection reduces the level of distortion typically found in global projections. It ensures the true area is maintained throughout the map.
4. Minimizes Distortion in Key Areas
The interrupted design and use of two projections help reduce distortion, especially along the equator and polar regions. The Goode’s Homolosine projection is particularly well-suited for thematic maps that need equal-area representation. These maps include those showing land use, ecosystems, or population densities.
5. Shape Distortion
While Goode’s Homolosine Projection maintains exact areas, it does distort the shapes of continents. This distortion is especially noticeable near the edges of the map or in the interrupted areas. For example, Greenland and Antarctica appear stretched or fragmented compared to their more compact shapes in other projections. Yet, the focus is on area rather than shape. This focus makes it useful for applications where relative size is more important than precise contour lines.
Historical Context
John Paul Goode developed the projection in 1923 as part of his work in cartography and geography. At the time, mapmakers were searching for projections. These projections needed to balance the need for precise area representation. They also needed to reduce distortions in global mapping. Goode’s Homolosine Projection was designed to resolve the inadequacies of other map projections used at the time. For example, the Mercator projection greatly distorted the size of landmasses, particularly near the poles.
Goode’s goal was to create a map that would serve thematic purposes. It was especially designed for use in textbooks. It offers a more balanced visual representation of the world. Its equal-area properties make it ideal for maps that need to compare relative land areas. They are also useful for displaying information about environmental or demographic phenomena.
Applications for Goode’s Homolosine Projection
Goode’s Homolosine Projection is commonly used in a variety of fields where the exact representation of area is important:
- Environmental Mapping: Due to its equal-area properties, it is often used in maps related to environmental science. These maps include global vegetation, climate zones, or land use. Environmentalists and ecologists gain from the ability to accurately compare the sizes of different biomes or ecosystems across the world.
- Thematic Mapping: It is often used for thematic maps that need to show global data in an easily interpretable way. For instance, population distribution, economic data, or even disease outbreaks can be more accurately represented using this projection.
- Textbooks and Education: The projection is also commonly found in geography textbooks. Its balance between area accuracy and minimized shape distortion helps students grasp the relative size of continents and countries. This balance avoids the extreme distortions seen in other projections, like the Mercator.
- Geopolitical Studies: In the context of geopolitical studies, Goode’s Homolosine Projection provides a more realistic visualization of the world. It is preferable to projections that distort the size of countries in higher latitudes. This is useful for discussions around global resources, land usage, and geopolitical influence.
Strengths and Limitations
Strengths of Goode’s Homolosine Projection
- Equal Area Representation: Ensures that all areas are proportionately represented, making it useful for global comparisons.
- Minimizes Shape Distortion: While not shape-preserving, the projection effectively reduces shape distortion. This is especially true when compared to other equal-area projections. The effect is most notable near the equator and poles.
- Optimized for Global and Thematic Mapping: Ideal for maps that emphasize data. This includes population, biodiversity, or climate. The relative size of regions is important in these maps.
Limitations of Goode’s Homolosine Projection
- Interrupted Layout: The projection is interrupted, which means some continuity in global views (particularly for oceans) is lost. This can be problematic for certain types of maps, like those related to oceanic phenomena.
- Shape Distortion at Higher Latitudes: Although area is preserved, the shapes of landmasses in higher latitudes (e.g., Greenland, Antarctica) become more distorted.
- Not Ideal for Navigational Purposes: Goode’s Homolosine Projection does not preserve angles or distances well. It is not suitable for navigation or detailed geographic reference.
How the Goode’s Homolosine Projection Compares to Other Projections
Mercator Projection
The Mercator projection is conformal. It preserves angles and is useful for navigation. Nevertheless, it drastically distorts the size of landmasses near the poles. Greenland, for example, appears much larger than it is in reality. This makes the Mercator unsuitable for thematic or global area comparisons. In contrast, Goode’s Homolosine maintains correct area proportions but does not preserve angles, making it unsuitable for navigational purposes.
Robinson Projection
The Robinson projection, like Goode’s Homolosine, aims to strike a balance between size and shape distortions. Yet, while Robinson focuses more on reducing shape distortion across the entire map, it is not an equal-area projection. This means that landmasses are not represented in their true proportions. Goode’s Homolosine, by contrast, focuses primarily on maintaining exact area representation.
Mollweide Projection
The Mollweide projection is another equal-area projection but does not use an interrupted layout. As a result, it introduces more distortion near the edges of the map. Goode’s Homolosine projection interrupted nature allows it to handle distortions more effectively. It shows the relative sizes of landmasses with less shape distortion.
Conclusion
Goode’s Homolosine Projection is a highly effective projection for thematic mapping, particularly where the precise representation of area is essential. Its interrupted layout is not ideal for certain applications, like navigation or displaying oceanic data. But, it can preserve proportional area with minimal shape distortion. This feature is valuable in the most populated regions. Hence, it is a valuable tool for geographers, environmentalists, and educators alike.
Its historical significance is particularly notable in moving beyond the limitations of earlier projections like Mercator. This solidifies Goode’s Homolosine projection as one of the most practical solutions for global cartographic representation. This is especially true in a world increasingly focused on thematic and data-driven map usage.
Other Elizabeth Streets Projection Essays
The Mercator Projection: History, Implications, and Drawbacks