[postgis-users] TIGER & SRID

[Stephen Woodbridge]

You might be interested in this. I will also note that I have 
transformed these files and compared the alignment with Navteq and found 
it to be significantly off. These island areas are supposed to be 
realigned as part of the MAF and Tiger realignment and improvement program.

-Steve W

-------- Original Message --------
Subject: Fw: Update Help with TIGER/Line Regional datums
Date: Wed, 30 Aug 2006 09:11:46 -0400
From: catherine.l.n.miller at census.gov
To: Stephen Woodbridge <woodbri at swoodbridge.com>
CC: tiger at census.gov


Mr. Woodbridge,

Please ignore my earlier message.  We recently determined the regional
datums for Hawaii, Guam, and the Commonwealth of the Northern Mariana
Islands in preparation for converting them to NAD83.

Hawaii
Hawaii County, HI (15001) -- Old Hawaiian Datum
Honolulu County, HI (15003) -- Old Hawaiian Datum for Oahu Island and local
astronomic datums for all islands northwest of 161 degrees west longitude
Kalawao County, HI (15005) -- Old Hawaiian Datum
Kauai County, HI (15007) -- Old Hawaiian Datum for Kauai Island and local
astronomic datum for Kaula Rock
Maui County, HI (15009) -- Old Hawaiian Datum

American Samoa
Eastern District, AS (60010) -- American Samoa 1962 Datum
Manu'a District, AS (60020) -- American Samoa 1962 Datum
Rose Island, AS (60030) -- Local Astronomic Datum
Swains Island, AS (60040) -- Local Astronomic Datum 1939
Western District, AS (60050) -- American Samoa 1962 Datum

Guam (66010) -- Guam 1963 Datum

Commonwealth of the Northern Mariana Islands
Northern Islands Municipality (69085) -- Guam 1963 Datum (Agrihan,
Alamagan, Anatahan, Guguan, Medinilla, Pagan, and Sarigan Islands) and
Local Astronomic Datums (Asuncion, Maug, and Farallon De Pajaros Islands)
Rota Municipality (69100) -- Guam 1963 Datum
Saipan Municipality (69110) -- Guam 1963 Datum
Tinian Municipality (69120) -- Guam 1963 Datum

Cathy Miller
Geographic Products Management Branch
Geography Division
U.S. Census Bureau


----- Forwarded by Catherine L N Miller/GEO/HQ/BOC on 08/30/2006 08:28 AM
-----

              Catherine L N
              Miller/GEO/HQ/BOC
                                                                         To
              08/30/2006 08:19          Stephen Woodbridge
              AM                        <woodbri at swoodbridge.com>
                                                                         cc
                                        tiger at census.gov
                                                                    Subject
                                        Re: Help with TIGER/Line Regional
                                        datums(Document link: Catherine L N
                                        Miller)









Mr. Woodbridge,

Because the regional datums used outside the 48 contiguous states was not
relevant to the Census Bureau's purposes for creating maps, the TIGER
database documentation did not record the specific datum of our source
material for Alaska, Hawaii and the Pacific Island Areas.  We are in the
process of attempting to determine which regional datum(s) were used for
these areas.  To date we have been able to determine that the American
Samoa 1962 (ASD62) is used in American Samoa and this information appears
in the metadata for the 2005 Second Edition TIGER/Line files.  We are still
attempting to determine the datums for the other areas and will include
this information in the metadata as it becomes available.

Cathy Miller
Geographic Products Management Branch
Geography Division
U.S. Census Bureau





              Stephen
              Woodbridge
              <woodbri at swoodbri                                          To
              dge.com>                  tiger at census.gov
                                                                         cc
              08/29/2006 06:00
              PM                                                    Subject
                                        Help with TIGER/Line Regional
                                        datums










Hello,

I have not been able to determine what specific regional datums are
being used for for Hawaii and the Pacific Island Areas.

http://www.census.gov/geo/www/tlmetadata/metadata.html

States: "Regional datums are used for Hawaii and the Pacific Island Areas."

The metadata states:

Spatial_Reference_Information:
    Horizontal_Coordinate_System_Definition:
      Geographic:
        Latitude_Resolution: 0.000458
        Longitude_Resolution: 0.000458
        Geographic_Coordinate_Units: Decimal degrees
      Geodetic_Model:
        Horizontal_Datum_Name:  North American Datum of 1983 in the 48
          contiguous states, the District of Columbia, Alaska, Puerto Rico,
          and the Virgin Islands of the United States.  Regional datums
          were used in Hawaii and the Pacific Island Areas (American Samoa,
          Guam, and the Commonwealth of the Northern Mariana Islands)
        Ellipsoid_Name:  Geodetic Reference System 80 where the datum is
          the North American Datum of 1983
        Semi-major_Axis:  6,378,137
        Denominator_of_Flattening_Ratio:  298,257

And I have search the Census site for other details, to no avail.

Can you please send me the details of the regional datums, specifically
what are the spatial reference system details that you are using.


Thank you,
    -Stephen Woodbridge