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ENV510 Landscape Ecology and GIS
Definitions
& descriptions | Concepts
& issues | Setting
up GIS | Using
GIS
| Applications
Representation
| Spatial data | Referencing
| Coordinates | Projections
| Georeferencing |
GPS | Data
issues | Accuracy
| Error | Management
Coordinate
systems are used to identify locations on the Earth's surface i.e. they provide
a common frame of reference. The usual coordinate systems use in a GIS are plane,
orthogonal cartesian
coordinates. These are orientated conventionally ie north-south and
east-west. Lines of longitude or the east-west position are related to the Greenwich
meridian and lines of latitude or the north-south position are related to the
equator.
The earth's surface is not flat but is almost spherical. In fact it is flattened at the poles so ellipsoids are used for mapping the true curved surface of the earth.
Read
http://www.geog.ubc.ca/courses/klink/gis.notes/ncgia/u26.html#UNIT26
This will provide further information on what is meant by general coordinate systems. You can think about the discussion and exam questions but you do not need to answer them.
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