DataTerminology.comNEW
Also known as: Cartographic Projection
A mathematical transformation of Earth’s curved surface to a flat map, trading off distortions in area, shape, distance, or direction.
DESCRIPTION
Map projections convert geographic coordinates on the ellipsoid or sphere into planar coordinates for visualization and analysis. Different projections optimize properties like area preservation, shape fidelity, or distance accuracy. Choices include Mercator, equal-area, and conformal families. Cartographers select projections based on region size, purpose, and accuracy requirements. Misapplied projections can distort metrics and mislead analysis.
ALTERNATIVE DEFINITIONS
USGS
A map projection is a method for representing part of the surface of the earth or a celestial sphere on a plane.
Defines projection as representation method onto a plane.
Wikipedia
A map projection is a systematic transformation of the latitudes and longitudes of locations from the surface of a sphere or an ellipsoid into locations on a plane.
Emphasizes systematic transformation and geodetic basis.
RELATED TERMS
Projected Coordinate System Mercator Web Mercator Lambert Conformal Conic Equal-Area Projection Conformal Projection Geodesy Datum Coordinate Reference System
COMPETING TERMS
RELATIONS
- Broader: Projection
KNOWLEDGE AREAS
Domain & Business Context Data Visualization Data Architecture
TARGET AUDIENCE
Data Scientist BI Specialist Data Engineer Solution Architect Data Analyst
EXTERNAL SOURCES
- Wikipedia - Map projection
- EPSG - Coordinate reference system registry
- PROJ - Projection library documentation
- Esri - Guidance on choosing projections
TOP QUESTIONS
Why are Map Projections necessary for analysis?
They enable spatial computations and visualization on flat surfaces. Without projections, planar measurements and map-based analytics are inconsistent.
Category: Relevancy
What distortions occur in Map Projections?
Area, shape, distance, and direction can be distorted. Different projections preserve specific properties while sacrificing others.
Category: Example
What is a common mistake in choosing Map Projections?
Using Web Mercator for area comparisons misleads results. Prefer equal-area projections for thematic mapping of regions.
Category: Mistakes
What risks arise from misapplied Map Projections?
Misinterpretation of distances, areas, and directions can distort policy or business decisions. Validate projections for intended use.
Category: Risks
How do I select a Map Projection for a country-scale map?
Use projections tuned to mid-latitudes or region geometry, such as Lambert Conformal Conic, balancing shape and area considerations.
Category: Requirements
Are Map Projections standardized?
Yes, EPSG codes identify coordinate reference systems and projections. Libraries like PROJ implement them consistently.
Category: Opinion
How do datums relate to Map Projections?
A datum defines Earth’s shape and origin; projections transform coordinates defined under a specific datum to a plane.
Category: Example
Where can I learn about Map Projections?
Start with USGS and EPSG resources, then explore PROJ docs and GIS vendor guidance.
Category: Requirements
What’s a misunderstanding about Map Projections?
No single projection is best universally; the optimal choice depends on geography and analytic purpose.
Category: Misunderstanding