Projections - A Primer of GIS: Fundamental Geographic and Cartographic Concepts - page 83

planar projections. All three projections may have oblique aspect (based on
Jones, 1997, p. 75).
Tangent
Figure 4.7 illustrates differences in how projections “touch” the developable
surface of a reference globe, another important characteristic of projections.
These places of contact between the developable surface and spheroid, ellip-
soid, or geoid are the most accurate for any projection and are called stan-
dard parallels or standard lines .
Projection Properties
Projections alter the four spatial relationships (angles, areas, distances, and
direction) found on a three-dimensional object. Most projections only main-
tain one of the properties in a specific manner—for example, equidistant
projections preserve distance from one point to all other points. Many projec-
tions, especially projections used for larger areas, compromise all these
properties.
The projections that preserve angular relationships from one point are
called conformal , but you should remember that conformal refers to the pres-
ervation of angles only, never shapes. Figure 4.8 includes a Lambert
Some possible aspects for conical, cylindrical, and planar projections.
Data source: Jones (1997).