Mapping Toolbox™

Using Map Projections and Coordinate Systems

All geospatial data must be flattened onto a display surface in order to visually portray what exists where. The mathematics and craft of map projection are central to this process. Although there is no limit to the ways geodata can be projected, conventions, constraints, standards, and applications generally prescribe its usage. This chapter describes what map projections are, how they are constructed and controlled, their essential properties, and some possibilities and limitations.

What Is a Map Projection?	Flattening the Earth to comprehend its features
Quantitative Properties of Map Projections	What properties of maps the geometric construction of map projections influences and constrains
The Three Main Families of Map Projections	Making maps by projecting the globe onto cylinders, cones, and planes
Projection Aspect	How the orientation vector affects map displays
Projection Parameters	What parameters projections can have and how they influence the appearance and properties of maps
Visualizing and Quantifying Projection Distortions	Calculating and communicating the kinds of spatial error that map projections can have
Accessing, Computing, and Inverting Map Projection Data	Projecting coordinates using objects and retrieving projected coordinates from figure objects
Working with the UTM System	Understanding the Universal Transverse Mercator family of map projections
Summary and Guide to Projections	The properties of each supported Mapping Toolbox™ map projection

If you are not acquainted with the types, properties, and uses of map projections, read the first four sections. When constructing maps—especially in an environment in which a variety of projections are readily available—it is important to understand how to evaluate projections to select one appropriate to the contents and purpose of a given map.

Manipulating Raster Geodata

What Is a Map Projection?