Transverse Mercator Projection
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Introduction
Transverse Mercator projection is a conformal cross-cylindrical projection that cuts the Earth ellipsoid along the meridian (central meridian) and unfolds it into a plane. It is widely used in large-scale topographic mapping and national coordinate systems (such as the UTM coordinate system) in mid-latitude regions.
Projection Basics
- Projection Basics
- Projection method: Conformal transverse cylindrical projection, which cuts the ellipsoid along the central meridian (meridian) and unfolds it into a plane.
- Earth model: Based on an ellipsoid (such as WGS84), not a sphere.
- Key parameters
- Central meridian (λ₀): The axis of symmetry of the projection, with minimal deformation.
- Latitude of origin (φ₀): Usually the equator (φ₀=0°), but can be adjusted.
- Scale factor (k₀): The scale on the central meridian (usually 1.0, that is, no scaling).
- Coordinate system
- Plane coordinates:
- Easting (X): Along the central meridian, in meters.
- Northing (Y): Perpendicular to the central meridian, in meters.
- Coordinate origin: Usually located at the intersection of the central meridian and the latitude of the origin.
Pros
- Conformal characteristics: keep angles and shapes without deformation, suitable for surveying and mapping that requires precise direction and shape;
- High local accuracy: extremely small deformation near the central meridian, suitable for high-precision surveying and mapping of small and medium-sized areas;
- Zone control: effectively limit projection deformation through zone technology (such as UTM’s 6° zone), and improve accuracy in large areas.
Cons
- Deformation increases with distance: the farther away from the central meridian, the greater the deformation of area and distance;
- Complex cross-zone processing: Zonal projection requires complex conversion of cross-zone areas, increasing the difficulty of data processing;
- Not applicable to polar regions: deformation is significant in high-latitude areas and needs to be combined with other projection methods.
Application Scenario
It is suitable for large-scale topographic maps, engineering surveys, national surveying and mapping systems and high-precision navigation in mid-latitude areas.
Example
- Transverse Mercator projection.
- Transverse Mercator projection.
Related GIS Projections
Lambert Azimuthal Equal-Area Projection