Map Projections Explained: Mercator, Robinson & Winkel Tripel

Beyond cylindrical projections, cartographers use conic and azimuthal systems for specific mapping needs. The conic projection wraps a cone around Earth, tangent at mid-latitudes, making it ideal for mapping large territorial areas in the mid-latitudes like the United States, China, Canada, and Russia. However, it cannot accurately represent equatorial regions like Brazil. The azimuthal (planar) projection represents any Earth surface portion with high fidelity, particularly polar regions. The United Nations uses this projection for its flag, placing the North Pole at the center. In this system, parallels are concentric circles while meridians radiate from the pole. This projection symbolizes equal representation of all countries, as every nation appears equidistant from the central point. It is particularly relevant for topics like Arctic resource exploration and Antarctic research.

This section introduces the Transverse Mercator (TM) projection family, including Universal (TM), Regional (RPM), and Local (LTM) variants. All are conformal projections using transverse secant cylinders. The fundamental difference between systems is fuso amplitude: TM uses 6° zones, RPM uses 2° zones, and LTM uses 1° zones. Each fuso has a central meridian and two secant meridians at approximately 1°37' from center. The ellipsoid projects from outside to inside between secant meridians, and from inside to outside beyond them, causing distance reduction near center and expansion at borders.

Three main cartographic projections exist: (1) Mercator Cylindrical - oldest projection, suitable for low latitudes (0-30°), causes deformation at higher latitudes; (2) UTM (Universal Transverse Mercator) - most widely used, divides Earth into 60 zones of 6° each, used by Peru for national cartography; (3) Conic (Lambert) - suitable for mid-latitudes (30-60°), used by US, Canada, Chile, Argentina; (4) Azimuthal Polar - suitable for high latitudes (60-90°), deformation increases at lower latitudes. Each projection has specific advantages and limitations based on geographic location.

Las proyecciones cartográficas transforman matemáticamente la superficie curva de la Tierra en planos. Tipos principales: cónica (zonas tropicales), azimutal (polares), y cilíndrica (más usada por mayor superficie terrestre). La proyección UTM (Universal Transversal de Mercator) divide la Tierra en zonas de 6° longitud y bandas de 8° latitud. El Perú se encuentra en zonas 17-19 y bandas M-L-K. Los códigos EPSG identifican combinaciones específicas de datum, proyección, zona y hemisferio.

Map projections are systems of meridians and parallels on which maps are drawn. Three main types exist: cylindrical projection (wraps Earth in a cylinder touching at the equator, best for 0-30° latitude), conic projection (uses a cone touching at mid-latitudes 30-60°, best for mid-latitudes), and azimuthal/polar projection (represents high latitudes 60-90°). The UTM (Universal Transverse Mercator) is a cylindrical projection dividing the world into 60 zones of 6° longitude each, representing from 84°N to 80°S with minimal deformation. Peru uses UTM zones 17, 18, and 19 since 1958.

EPSG (European Petroleum Survey Group) codes provide standardized identification for coordinate reference systems, enabling software interoperability. WGS 84 uses EPSG code 4326. ETRS 89 (European Terrestrial Reference System 1989) for Germany uses codes 25832 and 25833 for zones 32 and 33. Historical German surveying systems used codes 31466 and 31469. In GIS software, the project CRS defines how all layers display and analyze within the workspace. Users enter EPSG codes to set the project CRS, with software displaying coverage indicators. Layers can have different CRS than the project, requiring awareness of reprojection implications. Understanding these codes ensures correct coordinate interpretation across geographic information systems.

Coordinate Reference Systems (CRS) define how geographic locations are represented mathematically. QGIS uses EPSG codes to identify specific projections, such as EPSG:4326 for WGS84 geographic coordinates and EPSG:3857 for Web Mercator used by web maps. Changing the project CRS affects how all layers are displayed and measured. Most web mapping services use Web Mercator (EPSG:3857), so changing the project CRS to match ensures proper alignment with basemaps and accurate measurements.

Every spatial dataset must be associated with a Coordinate Reference System (CRS) that defines how locations are measured and displayed. CRS selection involves choosing between geographic coordinates (latitude/longitude) and projected coordinates (like UTM). Each region has specific appropriate CRS codes; for example, João Pessoa, Brazil uses EPSG:31985 (UTM Zone 25S). Selecting the correct CRS ensures accurate measurements and proper alignment with other spatial data. The EPSG code uniquely identifies the specific coordinate system for a given location.

Common CRS and their EPSG codes: WGS84 (4326) for GPS/GPX files, JGD2000 (2443-2460) and JGD2011 (666-6687-5) for forest maps, JGS (3857) for legacy maps. JGD2011 was introduced after the Great East Japan Earthquake to correct reference point positions. Web Mercator (EPSG:3857) is used for internet maps but causes area distortion. Understanding these codes is essential for accurate GIS work and data interoperability.

EPSG codes are numerical identifiers for coordinate reference systems. EPSG:3857 represents Web Mercator with WGS84 datum, commonly used for web mapping. EPSG:4612 represents JGD2000 with Japanese Plane Coordinate System, used for Japanese government map data. Changing CRS in QGIS involves using the globe icon selector to search and select the desired EPSG code. The coordinate system affects how data is displayed and analyzed.

Traditional world maps, such as the Mercator projection commonly used in schools, distort geographic sizes and place Europe at the top, creating a Eurocentric worldview that has historically marginalized African and other non-European regions; this bias can be challenged by using alternative map orientations that place Africa at the top, as demonstrated by historical maps from around 1100 AD and modern cartographers like Stuart McArthur who created maps with Australia at the top.

Eurocentrism refers to the practice of evaluating other states and cultures from a European perspective, with Europe serving as the central reference point for all measurements. This concept explains why traditional world maps appear to center Europe, making other continents appear smaller than they actually are. For example, Greenland appears nearly the same size as Africa on standard maps, even though Greenland is actually 14 times smaller. This distortion occurs because it is mathematically impossible to perfectly represent a spherical Earth on a flat 2D surface without some form of distortion.

Map projections reveal how cartography reinforces European centrality. The Mercator projection places Europe in the center with the equator at the bottom, making Europe appear larger than it actually is. This is because Europe was 'caput mundi' (head of the world) and needed to appear proportionally larger. The projection also makes the Mediterranean Sea appear contained by land, reinforcing the idea of Europe as the center of the world. This demonstrates how seemingly neutral representations of space actually encode specific political and cultural perspectives that privilege certain groups while marginalizing others.

All world maps are fundamentally imperfect because they attempt to project a spherical Earth onto a flat surface, creating unavoidable trade-offs between accurate distance representation and true area depiction. Historically, world maps were never intended for navigation but served as tools for imagining and constructing unknown territories. Maps have functioned as instruments of power, smuggling ideologies about trade routes, geopolitical boundaries, and threats. Western cartography has traditionally been Eurocentric, privileging European and North American perspectives. These maps project worldviews more than they depict reality, making them deeply connected to colonialism and empire. The classroom political maps that dominate education perpetuate these biases, shaping how generations perceive global geography and reinforcing cultural hierarchies.

Regionalization divides geographic space into regions based on common characteristics, serving administrative and planning purposes. The IBGE divides Brazil into five regions: North, Northeast, Central-West, Southeast, and South. Regionalization criteria vary by perspective—economists use economic indicators while biologists use ecological criteria. World maps conventionally place North at the top, but this is an arbitrary convention rather than geographical necessity. The Mercator projection, commonly used in schools, exaggerates polar regions while minimizing equatorial areas. Eurocentrism is the practice of placing Europe at the center of maps, creating visual hierarchies where European countries appear larger and more central while other regions appear smaller and peripheral. No map is perfectly accurate—all involve distortion, and the choice of projection carries political and cultural implications reflecting and reinforcing European colonial perspectives.