1. A brief introduction to map projections By Mark VanderVen vanderm6@cc
A brief introduction to map projections By Mark VanderVen 

2. We’ll define it as the study, science, history, and art of map-making.
Cartography
No simple, easy definition
We’ll define it as the study, science, history, and art of map-making. 

3. Cartography Comprised of many techniques and methods.
Includes measuring the earth's shape, distances, and features
Collect and store information about terrain, places and people
Create and design processes for graphical representation of data
Print and publish spatial information.
Adapt three-dimensional features to flat models

4. A spherical surface (or section of) cannot be transformed to a planar (flat) surface without incurring some distortion

5. Projection
“A mathematical development of one surface onto another. In the cartographic context, one surface is the earth and the other is a flat surface such as a map. The mathematics usually convert from the spherical coordinates of latitude and longitude to a Cartesian coordinate system. The projection is one element of a coordinate system definition.” Norm's GIS Glossary

6. Second Defintion
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. Maps cannot be created without map projections. All map projections necessarily distort the surface in some fashion.

7. …more simply put…
A map projection is a flat map surface representing all or part of a spherical surface (Earth).

8. REMINDER
A spherical surface (or section of) cannot be transformed to a planar (flat) surface without incurring some distortion

9. Map properties that can be distorted
Shape
Area
Distance
Direction

10. Distance ?

11. Area

12. Shape?

13. Direction?

14. For a web page on coordinate systems see:

15. Comparisons
ESRI “No Projection” (Lat/Long)
Mercator

16. Conclusions Different projections are used to preserve
Shape
Area
Distance
Direction
No projection can do all simultaneously.

17. For More What on Earth are Map Projections Prof. Alan Saalfeld
Geography
Ohio State University
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