NGS_Geodetic_Control (MapServer)

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Service Description: This map displays National Geodetic Survey (NGS) classifications of geodetic control stations located within the US.

Map Name: NGS Geodetic Control Stations

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Description: This map displays National Geodetic Survey (NGS) classifications of geodetic control stations located within the US. This map shows geodetic control stations maintained by the National Geodetic Survey (NGS) to provide a base reference for latitude, longitude, and height throughout the United States. Stations are located within the US and trust Territories. Separate layers are used to identify the quality of stations as combined control (horizontal and vertical), horizontal control, vertical control, and lower quality, along with locations that are part of the Continuously Operating Reference Stations (CORS) network. A station can fall within multiple categories. For example, a horizontal control station could also have low quality Othometric Height, and be part of the CORS network. Station Classifications: CORS – stations which are part of the Continuously Operating Reference Stations (CORS) network and comprised of permanently operating Global Positioning System (GPS) receivers. They are identified by the attribute DATUM_TAG = '(CORS)'. Combined Control Stations (Horizontal and Vertical) – are stations meeting the criteria for both horizontal and vertical stations. Horizontal Control Stations – are stations with precise latitude, longitude. They are identified by attribute POS_SRCE = 'ADJUSTED'. Vertical Control Stations – are stations with precise Orthometric Heights which measure elevation in meters indicating the height above the Geoid. They are identified by attributes ELEV_SRCE = 'ADJUSTED', 'ADJ UNCH', 'POSTED', 'READJUSTED', 'N HEIGHT', 'RESET', 'GPS OBS(2006', 'LEVELING', or 'LEVELING(200'. Low Quality Stations – are stations with low quality latitude, longitudes (horizontal) and/or low quality Othometric Heights (vertical). Low quality latitude, longitudes are identified by attributes POS_SRCE = 'GPS_OBS', 'NO CHECK', 'HD_HELD1', 'HD_HELD2', or 'SCALED', while low quality Othometric Heights are identified by attributes "ELEV_SRCE" = 'GPSCONLV ', 'VERT ANG', 'H LEVEL', 'VERTCON', or 'SCALED'. Data is shown in three different scale ranges and is not shown at a scale smaller than 1:60,000,000. 1:4,000,001 to 1:60,000,000 – CORS and Combined Control Stations are shown 1:500,001 to 1:4,000,000 – CORS, Combined Control, Horizontal Control Stations and Vertical Control Stations are shown 1:1 to 1:500,001 – CORS, Combined Control, Horizontal Control, Vertical Control, and Low Quality Stations are also shown Data is shown reprojected to WGS_1984_Web_Merctor_Auxillary_Sphere utilizing a NAD_1983_HARN_To_WGS_1984_3 Geographic Transformation. Data was extracted from NGS datasheets which are available at http://www.ngs.noaa.gov/cgi-bin/datasheet.prl. The NGS datasheet is a text document which summarizes key geodetic information stored in the NGS database. Further descriptions of the classifications are available at http://www.ngs.noaa.gov/cgi-bin/datasheet.prl?Explain=SF_METADATA. This data was downloaded on 2/14/2011; updated data is available from NGS datasheets on a monthly basis.

Copyright Text: National Ocean and Atmospheric Administration (NOAA), National Geodetic Survey (NGS) and cooperating organizations

Spatial Reference: 3857

Single Fused Map Cache: false

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Document Info:

Title: NGS Geodetic Control Stations
Author: Esri
Comments: The National Geodetic Survey (NGS) serves as the Nation's depository for geodetic data. NGS provides the public with survey control information. This map shows geodetic control stations maintained by the National Geodetic Survey (NGS) to provide a base reference for latitude, longitude, and height throughout the United States. Stations are located within the US and trust Territories. Separate layers are used to identify the quality of stations as combined control (horizontal and vertical), horizontal control, vertical control, and lower quality, along with locations that are part of the Continuously Operating Reference Stations (CORS) network. NOTE: A single station can be classified multiple ways. For example, a horizontal control station could also have low quality Orthometric Height, and be part of the CORS network. Station Classifications: CORS Network – are stations which are part of the Continuously Operating Reference Stations (CORS) network and comprised of permanently operating Global Positioning System (GPS) receivers. They are identified by the attribute DATUM_TAG = '(CORS)'. Combined Control Stations (Horizontal and Vertical) – are stations meeting the criteria for both horizontal and vertical stations. Horizontal Control Stations – are stations with precise latitude, longitude. They are identified by attribute POS_SRCE = 'ADJUSTED'. NOTE: Horizontal Control Stations that are also Vertical Control Stations have been removed from this category and can be found in the Combined Control Stations category. Vertical Control Stations – are stations with precise Orthometric Heights which measure elevation in meters indicating the height above the Geoid. They are identified by attributes ELEV_SRCE = 'ADJUSTED', 'ADJ UNCH', 'POSTED', 'READJUSTED', 'N HEIGHT', 'RESET', 'GPS OBS(2006', 'LEVELING', or 'LEVELING(200'. NOTE: Vertical Control Stations that are also Horizontal Control Stations have been removed from this category and can be found in the Combined Control Stations category. Low Quality Stations – are stations with low quality latitude, longitudes (horizontal) and/or low quality Orthometric Heights (vertical). Low quality latitude, longitudes are identified by attributes POS_SRCE = 'GPS_OBS', 'NO CHECK', 'HD_HELD1', 'HD_HELD2', or 'SCALED', while low quality Orthometric Heights are identified by attributes "ELEV_SRCE" = 'GPSCONLV ', 'VERT ANG', 'H LEVEL', 'VERTCON', or 'SCALED'. Data is displayed in several different scale ranges and is not displayed at a scale beyond than 1:60,000,000. 1:1,000,001 to 1:60,000,000 – CORS Network is displayed. 1:250,001 to 1:1,000,000 – CORS Network and Combined Control Stations are displayed. 1:50,001 to 1:250,000 – CORS Network, Combined Control, Horizontal Control Stations and Vertical Control Stations are displayed. 1:1,001 to 1:50,000 – CORS Network, Combined Control, Horizontal Control, Vertical Control, and Low Quality Stations are displayed. Data is displayed reprojected to WGS_1984_Web_Merctor_Auxillary_Sphere utilizing a NAD_1983_HARN_To_WGS_1984_3 Geographic Transformation. Data was extracted from NGS datasheets which are available at http://www.ngs.noaa.gov/cgi-bin/datasheet.prl. The NGS datasheet is a text document which summarizes key geodetic information stored in the NGS database. Further descriptions of the classifications are available at http://www.ngs.noaa.gov/cgi-bin/datasheet.prl?Explain=SF_METADATA. This data was downloaded on 6/14/2011; updated data is available from NGS datasheets on a monthly basis.
Subject: This map displays National Geodetic Survey (NGS) classifications of geodetic control stations located within the US.
Category:
Keywords: National Ocean and Atmospheric Administration, NOAA, National Geodetic Survey, NGS, horizontal control, vertical control, latitude, longitude, Orthometric Height, Survey Control Stations, Continuously Operating Reference Stations, CORS, A-16 Framework, Geodetic Control, Global Positioning System, GPS, Geodetic, NSRS, ellipsoid height, benchmark
Credits: National Ocean and Atmospheric Administration (NOAA), National Geodetic Survey (NGS) and cooperating organizations
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TextAntialiasingMode: Force

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