GEOG 2301 Coordinate Systems GIS Roots 2

1. GEOG 2301 � Coordinate SystemsGIS Roots 2 Dr. Stuart Murchison

2. Coordinate Systems

3. Coordinate Systems

4. Coordinate Systems

5. Coordinate Systems Using Latitude and Longitude, or geographic coordinates, in a GIS means that all maps can be transformed into a map projection in the same way!! It is important to note that even geographic coordinates still need to have their spheroid or datum specified, since locations change from one datum to another!!

6. The Universal Transverse Mercator The Universal Transverse Mercator or UTM coordinate system is commonly used in GIS. It has been used to map most of the US and even Mars. UTM splits the world into 60 pole-to-pole strips, each 6 degrees of Long. The first �ZONE� starts at 180 degrees (or the International Date Line) The final�zone� starts at 174 degrees east and extends to the date line.

7. The Universal Transverse Mercator

8. Map of Mars

9. The Universal Transverse Mercator

10. The Universal Transverse Mercator Each UTM zone has its own central meridian from which it spans 3 degrees west and 3 degrees east of that central meridian. The cylindrical methodology is the same as that for the Transverse projection. Note that the position of the cylinder rotates systematically around the globe. X- and y-coordinates are recorded in meters. The origin for each zone is the Equator and its central meridian. To eliminate negative coordinates, the projection alters the coordinate values at the origin. The value given to the central meridian is the false easting, and the value assigned to the Equator is the false northing. For locations in the Northern Hemisphere, the origin is assigned a false easting of 500,000, and a false northing of 0. For locations in the Southern Hemisphere, the origin is assigned a false easting of 500,000 and a false northing of 10,000,000.

11. Metric System If the metric system gives you heartburn, here are a few tips to help you out. � The Truth What you can remember (to within 3 or 4 significant digits) � (You�ll be about 10% too short.) �1 meter = 3.280 feet 1 meter ~= 3 feet = 1.094 yards ~= 1 yard ~= 1 m � 100 m = 109 yards 100 m ~= 100 yards  = 328.08 feet ~= length of a football field 1000 m = 1 kilometer = 1 km 1000 m ~= 1/2 mile = 0.621 miles ~= 5/8 mile ��

12. Metric System Hectare Standard measurement of land area in metric system Equals 100 meters by 100 meters, or 10,000 square meters 100 hectares in a square kilometer Equivalent to 2.471 acres or 107,639 square feet. Acre is the standard measurement of land area in the US Originally, the area that could be worked by a team of oxen in a day (approximately!), and varied from state to state in Ben Franklin�s days! Equals 43,560 sq. feet, 4,840 sq. yards, or 10 sq. chains A surveyor�s chain (or Gunter�s Chain) is 66 feet long A rod, pole or perch is 16.5 feet, thus 4 rods equals a chain An acre is 1 chain by 10 chains, or 66 feet by 660 feet 640 acres in a square mile

13. The Military Grid Coordinate System Military Grid Reference System (MGRS) adapted by the U.S. Army in 1947 (Cold War). Uses lettering system along with numbers. Goals is to provide standard coordinate based �address locator� applicable to both analog and digital maps, supporting Disaster response Location based services (where is closest Joint Air Base?) Each primary UTM Grid Zone Designation (GZD) (the 6 � long. by 8 � lat. areas) identified by a number/letter combination (e.g 14S for north Texas, 18S for central east coast of US) Each GZD divided into 100,000 meter by 100,000 meter (100km x 100km) squares each identified by two letters (QB for DFW, UJ for Washington, D.C.) Within each 100,000-meter-square, points locations are based on UTM east/north coordinates Easting (�read across�) and northing (�then go up�) must always have the same number of digits. number of digits used depends on precision requirements

14. The Military Grid Coordinate System Example for Washington monument 18S--locates within the 6 � long. by 8 � lat. zone 18SUJ�locates within a 100km by 100km square 18SUJ20--Locates with a precision of 10 km (within a 10km square) 18SUJ2306 - Locates with a precision of 1 km (uses 2 digits) 18SUJ234064 � Locates with a precision of 100 meters (3 digits�within a city block) 18SUJ23480647 - Locates with a precision of 10 meters (4 digits�a single house) 18SUJ2348306479 - Locates with a precision of 1 meter (5 digits�a parked vehicle)

15. The United States National Grid

17. The State Plane Coordinate System began in 1930s for public works projects; popular with interstate designers. states divided into 1 or more zones (~130 total for US) each zone designed to maintain scale distortion to less than 1 part per 10,000 Texas has 5 zones running E/W: north (5326/4201), north central (5351/4202), Central (5376/4203), south central (5401/4204), south (5426/4205) (datumID/fipsID) Different projections used: transverse mercator (conformal) for States with large N/S extent Lambert conformal conic for rest (incl. Texas) some states use both projections (NY, FL, AK) oblique mercator used for Alaska panhandle

18. The State Plane Coordinate System each zone also has: unique standard parallels (2 for Lambert) or central meridian (1 for mercator) false coordinate origins which differ between zones, and use feet for NAD27 and meters for NAD83 (but we also use feet with this projection) (1m=39.37 inches exact used for conversion; differs slightly from NBS 1�=2.54cm) scale reduction used to balance scale across entire zone resulting in accuracy variation of approx. 1 per 10,000 thus 4 times more accurate than UTM

19. The State Plane Coordinate System

20. Let�s Put It All Together