Welcome to CaliforniaCalifornia Home <http://www.ca.gov/> 	

Welcome to California, picture montage
	
CaSIL Home <http://gis.ca.gov/index.epl>
Data Collections <http://gis.ca.gov/data.epl>
Imagery Acquisition Coordination <http://gis.ca.gov/planned/>
Frequently Asked Questions <http://gis.ca.gov/faq.epl>
California Mapping Coordinating Committee <http://gis.ca.gov/cmcc.epl>
Disclaimer <http://gis.ca.gov/disclaimer.epl>
Partners & Links <http://gis.ca.gov/links.epl>
Interactive Mapping <http://gis.ca.gov/ims.epl>
CaSIL Help <http://gis.ca.gov/help.epl>
Survey <#>

Related Links
	
California GIS Council <http://gis.ca.gov/council/index.epl>
CERES <http://ceres.ca.gov/>
USGS <http://www.usgs.gov/>
FGDC <http://www.fgdc.gov/>
Environmental Information Catalog <http://gis.ca.gov/catalog>
CalSpace UCD <http://calspace.ucdavis.edu/>

	
The California Spatial Information Library 	

	

My CA This Site

Digital Raster Graphics


  CA Projection

All maps in this series are represented in the Albers Equal Area
Projection. This information is included in the header file of each
geotiff image. The following is the standard text representaiton of the
geotiff header:

Example 1. Geotiff Header Information

For *California Teale Albers, NAD27 projection:*

  Geotiff_Information:
     Version: 1
     Key_Revision: 1.0
     Tagged_Information:
        End_Of_Tags.
     Keyed_Information:
        GTModelTypeGeoKey (Short,1): ModelTypeProjected
        GTRasterTypeGeoKey (Short,1): RasterPixelIsArea
        GeographicTypeGeoKey (Short,1): GCS_NAD27
        ProjectedCSTypeGeoKey (Short,1): User-Defined
        PCSCitationGeoKey (Ascii,38): "Albers Equal Area North American 1927"
        ProjectionGeoKey (Short,1): User-Defined
        ProjCoordTransGeoKey (Short,1): CT_AlbersEqualArea
        ProjLinearUnitsGeoKey (Short,1): Linear_Meter
        ProjStdParallel1GeoKey (Double,1): 34
        ProjStdParallel2GeoKey (Double,1): 40.5
        ProjNatOriginLongGeoKey (Double,1): -120
        ProjNatOriginLatGeoKey (Double,1): 0
        ProjFalseEastingGeoKey (Double,1): 0
        ProjFalseNorthingGeoKey (Double,1): -4000000
        End_Of_Keys.
     End_Of_Geotiff.

For *California Teale Albers, NAD83 projection:*

Geotiff_Information:
   Version: 1
   Key_Revision: 1.2
   Tagged_Information:
      End_Of_Tags.
   Keyed_Information:
      GTModelTypeGeoKey (Short,1): ModelTypeProjected
      GTRasterTypeGeoKey (Short,1): RasterPixelIsPoint
      GeographicTypeGeoKey (Short,1): GCS_NAD83
      ProjectedCSTypeGeoKey (Short,1): User-Defined
      ProjectionGeoKey (Short,1): User-Defined
      ProjCoordTransGeoKey (Short,1): CT_AlbersEqualArea
      ProjLinearUnitsGeoKey (Short,1): Linear_Meter
      ProjCenterLongGeoKey (Double,1): -120
      ProjNatOriginLatGeoKey (Double,1): 0
      ProjFalseEastingGeoKey (Double,1): 0
      ProjFalseNorthingGeoKey (Double,1): -4000000
      ProjStdParallel1GeoKey (Double,1): 34
      ProjStdParallel2GeoKey (Double,1): 40.5
      PCSCitationGeoKey (Ascii,38): "Albers Equal Area North American 1983"
      ProjectedCSTypeGeoKey (Short,1): User-Defined
      ProjLinearUnitsGeoKey (Short,1): Linear_Meter
      End_Of_Keys.
   End_Of_Geotiff.

The OpenGIS WKS representation of this projection is:

Example 2. OpenGIS WKS Projection Information

For *California Teale Albers, NAD27 projection:*

  PROJCS["Custom",
         GEOGCS["GCS_North_American_1927",
                DATUM["D_North_American_1927",
                      SPHEROID["Clarke_1866",6378206.4,294.9786982]],
                PRIMEM["Greenwich",0],
                UNIT["Degree",0.0174532925199433]],
         PROJECTION["Albers"],
         PARAMETER["False_Easting",0],
         PARAMETER["False_Northing",-4000000],
         PARAMETER["Central_Meridian",-120],
         PARAMETER["Standard_Parallel_1",34],
         PARAMETER["Standard_Parallel_2",40.5],
         UNIT["Meter",1]]         

For *California Teale Albers, NAD83 projection:*

  PROJCS["Custom",
         GEOGCS["NAD83",
                DATUM["North_American_Datum_1983",
                      SPHEROID["GRS 1980",6378137,298.257222101]],
                PRIMEM["Greenwich",0],
                UNIT["degree",0.0174532925199433]],
         PROJECTION["Albers"],
         PARAMETER["False_Easting",0],
         PARAMETER["False_Northing",-4000000],
         PARAMETER["Central_Meridian",-120],
         PARAMETER["Standard_Parallel_1",34],
         PARAMETER["Standard_Parallel_2",40.5],
         UNIT["Meter",1]]

The associated proj4 arguments are:

Example 3. Proj 4 parameters

For *California Teale Albers, NAD27 projection:*

  +proj=aea
  +lat_1=34.00
  +lat_2=40.50
  +lat_0=0.00
  +lon_0=-120.00
  +x_0=0.000 
  +y_0=-4000000.000 
  +ellps=clrk66 
  +units=m 

For *California Teale Albers, NAD83 projection:*

  +proj=aea 
  +lat_1=34.00 
  +lat_2=40.50 
  +lat_0=0.00 
  +lon_0=-120.00 
  +x_0=0.000 
  +y_0=-4000000.000 
  +ellps=GRS80 
  +units=m 
  +datum=NAD83

The corner coordinates vary with each individual map.

Back to Top of Page <#PageTop>

� 2000 State of California. Arnold Schwarzenegger, Governor.Privacy
Policy <http://resources.ca.gov/privacy.html> E-mail the Webmaster
<mailto:casil@gis.ca.gov>