Coordinate systems, map projections and Datums

What are the common cartographer tools?

Dividers, Douglas Protractor, scale rule, compass

True or False: Accuracy refers to the level of detail of a measurement

False: Accuracy refers to how the observed value compares to the true value

Azimuths

Defined as a horizontal angle measured clockwise from a north base line or meridian

How are azimuths read in north America

read from north in a clockwise direction

an azimuth of 030 means…

that the direction points 30 degrees clockwise from true north

Quadrant bearing

divide the world into four quadrants

heading

The direction that you are currently going - the direction that you would face

bearing

the direction that you would face to look at something or to travel to a specific location

you can express bearings in two ways:

Relative and Absolute

relative:

The position of something in relation to the way you are facing or travelling

Absolute

The compass direction you would face to look at something

The fundamentals components of modern day mapping

Coordinate system, map projections, datums

Geographic coordinate system:

defines the locations of features on a model of the earth - round objects

Projected coordinate system

used on planar or flat items

map projections

turns round objects into a flat object

Lambert conformal conic projection

Conic map projection common in Canadian maps

Albers Equal-Area Conic projection

uses a conic method of projection - scale and shape are not preserved - distortion is minimal between standard parallel lines

Mercator Projection

divides earth into 60 zones and projects each to the plane - UTM coordinate system

Datums

serves as a reference which allows us to describe points or locations and measure distance

Horizontal datums

deal with the X and Y components of a reference system

What are the two common horizontal datums

The north American Datum of 1983 (NAD 83) and the world Geodetic System of 1984 (WGS 84)

NAD 83 consist of a network of ———- reference points with —— satellite stations

250,000 reference points including 600 satellite stations

Vertical Datums

used for measuring the elevational component of points on the earths surface referred to as the Z coordinate

Vertical datums are either….

tidal (based on sea levels) or geodetic (ellipsoid models of the earth

most common vertical Datums used

Height Above Sea Level (HSL), Height above Ellipsoid (NAE) and mean sea level (MSL)