Geographic Coordinates & UTM Coordinates Flashcards
Coordinate Systems
- GCS
- Pro…
Datums
projected
A Coordinate System is a ? used to identify locations on a map (paper or digital) that are equivalent to grid locations on the earth.
grid
What is a Coordinate System?
A grid used to identify locations on a map (paper or digital) that are equivalent to grid locations on the earth.
Each 2D location is described by a pair of coordinates (x,?).
3D locations are described by a set of 3 coordinates?.
y
(x,y,z)
There are two types of coordinate systems:
- ??- commonly referred to as Latitude/Longitude (LL)
- P… C…
- most common is a form of ??? (UTM)
- Geographic Coordinates
- Projected Coordinates
- Universal Transverse Mercator (UTM)
- What are Geographic Coordinates commonly referred to as?
- What is the most common form of Projected Coordinates
- commonly referred to as Latitude/Longitude (LL)
- most common is a form of Universal Transverse Mercator (UTM)
Datums
- Every Coordinate System references a ?,
- which is typically named by the ? and the ?? it represents (eg. NAD83).
- Datum
- year; geographic region
- What is a datum? A Datum is a
- Consists of a:
- and its position and orientation with respect to the ?
- mathematical model of the earth’s shape
- spheroid
- earth
The Shape of the Earth
Most of us picture the earth, as a ball or sphere.
- Why can’t GPS use a sphere?
- What do we use instead?
- Because t would be off by several hundred meters
- a more refined shape
What is the Mean Equatorial Radius?
6,378 km
What is the Equatorial circumference?
40,000 km
Shape of the Earth
- Does the earth have a bigger diameter at the equator than through the poles?.
- The shape is called a ?.
- Position on earth is commonly calculated using the geometry of a ?.
- Yes
- Spheroid
- spheriod
A spheroid is a smooth, ? shape, used to approximate the shape of the ?.
Many spheroids have been defined for the Earth.
Examples:
Clarke 1866 spheroid
GRS 1980 spheroid
mathematical
earth
- Remember that a Datum is a mathematical model of the earth’s ? which consists of a
- spheroid AND its position and ? with respect to the earth
shape
orientation
We’ve defined the spheroid.
What about the position and orientation?
with respect to the earth
Some Common Datums
- WGS84 (The World Geodetic System 1984)is the datum that is…
- NAD83 (North American Datum 1983)is a datum frequently used for …(Uses the GRS80 spheroid)
- NAD27 (North American Datum 1927) is a datum that has been used on ? North American projects and maps. (Uses the Clarke 1866 spheroid)
- fundamentally used with GPS.
- North American datum and maps
- older
two Considerations for GPS Work
- Select and use a suitable datum.
- Select and use the right coordinate system.
- Set up…
- Understand…
- Need to know the…
- Select and use a suitable datum.
- Select and use the right coordinate system.
- Set up the appropriate coordinate system in the GIS software you are using.
- Understand the coordinate system being used by the map.
- Need to know the datum that the coordinates are referencing.
Choose a Suitable Datum
- You need to configure your GPS to use a Datum that is consistent with any other ?? you are working with.
- For instance, if you have a well survey plan that shows GCS NAD27 coordinates, then set your GPS unit to NAD27 ? if you want to navigate to the well centre.
- any other position information you are working with.
- Datum
datum
- You also will need to configure the GPS to display coordinates suitable for the ? you are doing.
- What are the two types of coordinate systems are used?
- project
1. Geographic Coordinates (Lat/Long)
2. Projected or Grid coordinates
- Geographic Coordinates refer to ? and ? (angular positions on the globe).
- Measured in ?,?,?
- ? uses Geographic Coordinates.
- You can set up a ? to display a coordinate system that is better suited to your work.
- Geographic Coordinates are not well suited for measuring ? or ? (eg. in metres or km).
- Latitude and Longitude
- Degrees, Minutes, Seconds.
- GPS
- GPS
- areas or distances
Geographic Reference Lines
The Primary Axes
- Equator: ? degrees Latitude.
- Prime Meridian: 0 degrees ?
Units
- ? Eg. 51° 30’ 00”
- or ?? Eg. 51.50 °
- 0
- Longitude
- Degrees, Minutes, Seconds
- Decimal degrees
Geographic Coordinates
- What is “Latitude”?
- Lines of Latitude are referred to as ‘’ (eg. Our border with the USA is the 49th parallel).
- the angular position from 0 at the Equator to 90 degrees North (+) or South (-) at the Poles.
- Parallels
Geographic coordinates
Longitude is the angular position from 0 to …………………………….. or West (-) of the ??.
Lines of Longitude are referred to as ‘?’.
180 degrees East (+) or West (-) of the Prime Meridian
Meridians
Prime and Other Meridians
- A meridian is an ? on the earth’s surface passing from the N Pole to the South Pole.
- The Prime Meridian is ? degrees longitude.
- It passes through ? , England from pole to pole.
- All other Meridians of Longitude are specified from 0 to ? degrees west (-) and east (+) of the Prime Meridian.
- The Meridian at 180 degrees is called the “???”
- arc
- zero
- Greenwich
- 180
- International Date Line.
Locations in Geographic Coordinates
If we use Olds College as an example, our location in Geographic Coordinates, using the WGS84 datum, are:
Lat: 51º 47’ 35” N Long:114º 05’ 40” W (in ?,?,?)
or 51.793055º, -114.094444º (in ? ?)
Degrees, Minutes, Seconds
decimal degrees
Converting DMS to Decimal Degrees
- There are 60 minutes in one?
- There are 60 seconds in one ?
- Therefore - there are 3600 secs in 1 degree
Example: 114º33’ 50” W can be converted to decimal degrees as follows:
- = 114 degrees +. 33/? + 50/?
- = 114 + 0.55 + 0.01388888
- = 114.56389 (Rounded to 5 decimal places)
- degree
- minute
- 33”= 33/60; 50’ =50/3600
_114º_33’ 50” W = 114 + 0.55 + 0.01388888 = 114.56389
Projected or Grid Coordinates
- A map projection is a representation of the ??, on a flat surface.
- Coordinate systems for map projections are some variation of ?-? c referenced to a pair of axes.
- ? units, commonly metres, are used.
- Grid coordinants are NOT well suited for measuring ? and ? on a map.
- curved earth
- X-Y coordinates
- Linear
- distances and areas
Projected Coordinates
There are numerous projected coordinate systems.
You can see a list when you configure your GPS receiver.
- One commonly used coordinate system is the UTM Coordinates (Universal Transverse ? ).
Mercator
UTM Zones
- In the UTM Coordinate system, the earth is divided into longitudinal zones, each ? degrees wide.
- Zones begin at the ???,
- and count up every ? degrees to the East.
- 6
- International Date Line
- 6
UTM Coordinate Maps
UTM coordinates may be used when the map fits within a ?.
So, UTM is used for a ?? like a county or a project, not for a large area like a ? or a continent.
For example, the Town of Olds is entirely inside UTM Zone 11, so UTM coordinates can be used for a town map.
zone
local map
country
UTM Reference Lines
- Locations are specified within a ?.
- Each zone has primary reference
- Equator: like the X-axis.
- Central Meridian: like the Y-axis.
- zone
- axis
