🔎 Transversal universel par Mercator: Définition et déclarations (2024)

FAQs

What is the difference between Mercator and transverse Mercator? ›

The transverse Mercator projection, also known as the Gauss-Krüger projection, is similar to Mercator except that the cylinder touches the sphere or ellipsoid along a meridian instead of the equator. The result is a conformal projection that does not maintain true directions.

The Universal Transverse Mercator (UTM) is a map projection system for assigning coordinates to locations on the surface of the Earth. Like the traditional method of latitude and longitude, it is a horizontal position representation, which means it ignores altitude and treats the earth surface as a perfect ellipsoid.

Noun. Mercator (plural Mercators) (chiefly attributive) An orthom*orphic map projection, in which meridians appear at right-angles to the equator, and lines of latitude are horizontal lines whose distance from each other increases with distance from the equator.

The UTM (Universal Transverse Mercator) coordinate system divides the world into sixty north-south zones, each 6 degrees of longitude wide. UTM zones are numbered consecutively beginning with Zone 1, which includes the westernmost point of Alaska, and progress eastward to Zone 19, which includes Maine.

Unlike the ellipsoidal Mercator, however, the Web Mercator is not quite conformal. This means that angles between lines on the surface will not be drawn to the same angles in the map, although they will not deviate enough to be noticeable by eye.

The central meridian in each UTM zone has a scale factor of 0.9996, which means that measurements along it fall short of true scale by 4 units in 10,000 (or 1 unit in 2,500). This is the maximum scale error anywhere within the zone and is the accuracy standard that the system was designed to meet.

This map, with its Mercator projection, was designed to help sailors navigate around the globe. They could use latitude and longitude lines to plot a straight route. Mercator's projection laid out the globe as a flattened version of a cylinder. All the latitude and longitude lines intersected at 90-degree angles.

The Gall-Peters projection, while also cylindrical, was designed to preserve area rather than bearing. The effect is a map that looks extremely odd, because the shapes are all wrong. Countries near the equator are vertically stretched, while countries near the poles are vertically squished, to a shocking degree.

In a Mercator projection, landmasses such as Greenland and Antarctica appear far larger than they actually are relative to landmasses near the equator. Despite these drawbacks, the Mercator projection is well-suited to marine navigation and internet web maps and continues to be widely used today.

This projection is good for navigation as directions are preserved; for example, on any point on the map, north points to the top of the chart. This makes Mercator projections the standard for navigational charts. The drawback to this projection is that size and distance are distorted at high latitudes.

What is Mercator also known as? ›

All teaching at the school was in Latin and he would read, write and converse in Latin, and give himself a new Latin name, Gerardus Mercator Rupelmundanus, Mercator being the Latin translation of Kremer, which means "merchant".

Distances from the origin are generally measured in feet, but sometimes are in meters. X distances are typically called eastings (because they measure distances east of the origin) and Y distances are typically called northings (because they measure distances north of the origin).

The Eastings start at the Central meridian at the number 500,000 (called the False Easting), not zero, thus eastings are never negative numbers. Northings are referenced from the Equator. Northings increase northward and decrease southward.

The UTM system itself was developed by the United States Army Corps of Engineers in the 1940s as part of a larger effort to create a standardized mapping system for military purposes. It was first used in the 1950s during the Korean War, and has since become widely adopted for civilian mapping and navigation.

About the projection

Ordinarily, in a Transverse Mercator projection, the central meridian is a line of true scale. In the UTM system, however, the projection is secant, so two lines of true scale are created—one on each side of the central meridian.

Because the linear scale of a Mercator map in normal aspect increases with latitude, it distorts the size of geographical objects far from the equator and conveys a distorted perception of the overall geometry of the planet.

The Peters projection is known for its area accuracy - no countries incorrectly in proportion to one another. On the other hand, the Mercator projection map by Gerardus Mercator has been around since it was developed in 1569, preserving angles and shapes with grace and ease.

Both examples are coordinate systems. The difference is that WGS 84 is a geographic coordinate system, and UTM is a projected coordinate system. Geographic coordinate systems are based on a spheroid and utilize angular units (degrees).