La selección de las proyecciones cartográficas – Instituto Geográfico Nacional

Summary

The video discusses how different map projections represent the Earth’s surface. It highlights the challenges of representing a spherical Earth on a flat plane, with various projections conserving different geometric properties, such as angles or surfaces. The Mercator projection, commonly used in navigation, distorts the size of continents but has historical significance, especially in the context of colonialism. In contrast, the Gall-Peters projection offers a more accurate size representation, though it is controversial among cartographers. The choice of projection can reflect not only technical needs but also political, moral, and economic values.

Takeaways

• 😀 The Earth's shape is close to an oblate spheroid, slightly flattened at the poles.
• 😀 Cartographic projections are mathematical formulas that help represent the Earth's surface on a flat plane.
• 😀 It is impossible to preserve all geometric properties (angles, surface areas, distances) when transforming a 3D sphere into a 2D map.
• 😀 Different map projections preserve different properties depending on their intended use.
• 😀 Political, moral, and economic values can influence the choice of cartographic projection.
• 😀 The size and shape of continents vary between different world maps, even though they may seem identical at first glance.
• 😀 By focusing on the equator, one can observe how the portion of territory represented in each hemisphere changes.
• 😀 The Mercator projection distorts sizes and shapes, especially near the poles, but has been historically used for navigation.
• 😀 The Mercator projection was popular in the 19th century, during the period of European colonialism and imperialism.
• 😀 The Gall-Peters projection preserves the relative size of landmasses, although it is controversial among cartographers due to concerns about its scientific accuracy.
• 😀 Different map projections serve various purposes, and the way a map represents the world can shape how we perceive it.

Q & A

What is the main idea behind cartographic projections?

Cartographic projections are mathematical formulations used to represent the Earth's three-dimensional surface on a two-dimensional plane, while preserving certain geometric properties such as angles, distances, or areas. However, it is impossible to preserve all properties simultaneously.

Why is it impossible to represent a sphere exactly on a plane?

A sphere cannot be represented exactly on a plane because the surface curvature of the sphere does not match the flatness of a plane. This leads to distortions in the representation of certain properties such as size, shape, or distance.

How do cartographic projections vary based on their intended purpose?

Different projections are selected depending on the specific purpose of the map. Some projections are designed to preserve angles (for navigation), while others may focus on accurately representing areas or distances. Each projection makes compromises in the accuracy of other properties.

What are the two key map projections discussed in the transcript?

The two key map projections discussed are the Mercator projection and the Gall-Peters projection. The Mercator projection is widely used for navigation but distorts sizes near the poles, while the Gall-Peters projection preserves areas but distorts shapes.

What is a major drawback of the Mercator projection?

A major drawback of the Mercator projection is that it distorts the size of continents, especially those near the poles. For example, it makes landmasses like Greenland appear much larger than they are in reality, which can skew perceptions of the world.

How does the Mercator projection reflect a Eurocentric worldview?

The Mercator projection tends to place Europe at the center of the map, giving it a larger and more prominent appearance compared to regions closer to the equator, such as Africa or Latin America. This central positioning has been linked to colonial and imperialist perspectives.

What does the Gall-Peters projection aim to represent more accurately?

The Gall-Peters projection aims to represent the relative sizes of continents more accurately by preserving their areas. This projection avoids the distortions found in the Mercator projection but does distort shapes, especially near the poles.

What controversy surrounds the Gall-Peters projection?

The Gall-Peters projection is controversial among cartographers due to its questionable scientific accuracy. While it preserves area proportions, the distortion of shapes, particularly near the poles, has led to debates over its legitimacy as a reliable map projection.

How have political and economic factors influenced the choice of map projections historically?

Political, economic, and cultural factors have historically influenced the choice of map projections. For example, the Mercator projection was commonly used during the colonial era because it emphasized European powers, making it easier for navigators and colonizers to map the world from a Eurocentric perspective.

How do different projections affect our perception of the world?

Different projections can significantly alter our perception of the world by distorting the size, shape, or position of continents and countries. The way a map is designed can shape how we understand global relationships, regional importance, and even historical narratives.