Commonly Used Coordinate Systems

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Commonly Used Coordinate Systems

• Universal Transverse Mercator (UTM)
• State Plane Coordinate System
• California State System (Teale) Albers
  Equal-Area Conic

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UTM Zones
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UTM Zone 10 N and S
Projection Surface Cylindrical Spatial
Properties Conformal, Shape and Direction
Projection Parameter False Easting 500,
000m False Northing 0 m Central Meridian
-123 Scale Factor 0.999600 Example of
Coordinate in Monterey X 602,585 (meters) Y
4,050,086 (meters)
Central Meridian
Value Decrease
Value Increase
Value Increase
False Easting 500,000
0m
0 m
10,000,000 m
Equator Origin
Value Increase
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Universal Transverse Mercator (UTM)

• 60 zones
• 6o wide
• Defined by central meridian (example 120 W)
• Preserves direction and small shapes (conformal
  projection).
• Extent is from 84N to 80 S.
• UTM coordinates are easily recognized by 6 digit
  for the x, and 7 digit for the y ( most of the
  time at latitudes of 15 and greater in the
  Northern Hemisphere)

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UTM

• Often found in military applications, and in many
  datasets.
• UTM system is secant with lines of scale 1
  located on both sides of the central meridian,
  the projection is conformal, so small features
  appear with the correct shape and scale is the
  same in all directions. (Scale is 0.9996 at the
  central meridian and at most 1.0004 at the edges
  of the zones
• Because there are effectively 60 different
  projections, maps will not fit together across a
  zone boundary.
• UTM maps easy to recognize, 6-digit integer
  followed by a 7-digit integer (e.g. 357302,
  7430129)
• Zones range from 84N to 80 S.

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Universal Transverse Mercator (UTM)
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State Plane Coordinate System

• Although distortions of the UTM system are small,
  they are too great for accurate surveying
• Plus zone boundaries follow arbitrary lines of
  longitude rather than jurisdictions.
• In the 1930s each US state agreed to adopt its
  own projections and coordinate system (SPC) in
  order to support these high-accuracy applications
  (especially cadaster).
• Projections were chosen to minimize distortion
  over the state.
• With large states they were broken into zones to
  increase accuracy.

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Cadasters and the US Public Land Survey System

• The cadaster is defined as the map of land
  ownership in an area, maintained for the purposes
  of taxing land, or of creating a public record of
  ownership.
• Parcels of land in a cadaster are often uniquely
  identified by number or by code.

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State Plane Zones for NAD 1983
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The State Plane Coordinate System (SPCS)
(continued)

• East-West oriented States use the Lambert
  Conformal Conic projection (ex. Tennesse)
• North-South oriented States use the Transverse
  Mercator projection (ex. Illinois)
• One zone in Alaska uses Oblique Mercator
• Based on the North American Datums NAD27 and
  NAD83
• Reference Eastings and Northings in feet

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State Plane Zones for NAD 1927 and 1983
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Teale Albers Projection ( California)
AKA CA State System, CA Albers Equal
Area Projection Surface Conical Spatial
Properties Equal Area (Equivalent) Projection
Parameters 1st Standard Parallel 34 00 00
2nd Standard Parallel 40 30 00 Central
Meridian -120 00 00 Central Parallel
Latitude of origin 00 00 00 False easting
(meters) 0 False northing (meters) -4,000,000
Example of Coordinate X -161,327
(meters) Y -149,199 (meters)
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Working with Coordinate Systems in ArcGIS

• On-the-fly projection
• Define Projection vs Project
• Predefined Projections (provided by ArcGIS)
• Projection File - .prj
• Text file stores projection information
• Data frame takes on the coordinate system of the
  first data layer added to the project.