# EAS221 Lecture Notes - Lecture 6: Universal Transverse Mercator Coordinate System, Lambert Conformal Conic Projection, North South Mrt Line

## Document Summary

Globes best represent earth surface,but are not practical. A projected coordinate system georeferences locations on the earth"s curved surface onto a flat surface. An imagery light @ centre of sphere, projecting location of features onto a flat plane. Developable surface aspect: what is the orientation of the developable sfc axis relative to the ellipsoid axis: ellipsoid axis: rotational axis of earth, developable surface axis: axis of symmetry. Oblique: only used for azimuthal developed surfaces. Transverse: axes are perpendicular to the rotational axis + How does map projection actually work: input unprojected angles (latitude/longitude) -> 2. apply a pair of functions (to calculate projected x,y -> 3. output a position in projected coordinates (e. g. mercator projection) Map projections always introduce some amount of error and distortion. But distortion can be minimized in one or more properties. Conformal projections preserve shape (of small areas) Equidistant projections preserve distance (between certain points)