Finding and Interpreting NGS Datasheets

Transcription

1 Finding and Interpreting NGS Datasheets

2 Finding a datasheet from the NGS website ( Click on Survey Mark Datasheets

3 Click on Datasheets Navigating the site

4 Navigating the site Learn more about datasheets If you already know the PID identifier If you already know the project coordinates. Very helpful for GPS calibration Search with a map

5 If you are using Lat/Long and Radius Need to know coordinates of the base point Can be Lat/Long Can be DMS or Decimal Degrees Can be SPC (meters only) You can find Lat/Long from other websites using a street address Try You can use Google Earth also

6 Select Input Type and Radius GPS Only if this is for GPS calibration

7 Indicates radial distance to the site in miles Using Lat/Long and Radius

8 Navigating the site Learn more about datasheets If you already know the PID identifier If you already know the project coordinates. Very helpful for GPS calibration Search with a map

9 Using the map search Requires the use of popup windows You will need to allow popups on your computer to use the map search

10 Using the map search (test popups)

11 Using the map search Use the navigation tools to zoom in on the desired area

12 Using the Map Search Click here Scale bar must be less than 5 miles long

13 Control Points are designated by a random number 2 3

14 Select the desired point(s) and click Get Datasheets

15 What Does a Datasheet Tell me? Permanent Identifier (PID) Lat/Long Height Orthometric (from MSL) Ellipsoid Height (only on GPS points) Other Coordinates SPC (State Plane Coordinates) UTM (Universal Transverse Mercator) Geocentric (X,Y,Z) for GPS points only

16 What Does a Datasheet Tell Me? Description of what kind of marker is at the point History of monumentation Descriptions of how to navigate to the marker location

17 Control Point PID - STATE/COUNTY- WI/WOOD USGS QUAD - WISCONSIN RAPIDS SOUTH (1984) *CURRENT SURVEY CONTROL * NAD 83(2007) (N) (W) ADJUSTED * NAVD (meters) (feet) GPS OBS EPOCH DATE X - 18, (meters) COMP Y - -4,566, (meters) COMP Z - 4,437, (meters) COMP LAPLACE CORR (seconds) DEFLEC09 ELLIP HEIGHT (meters) (02/10/07) ADJUSTED GEOID HEIGHT (meters) GEOID Accuracy Estimates (at 95% Confidence Level in cm) Type PID Designation North East Ellip NETWORK GRAND RAPIDS C GPS Height is measured by GPS observation to the closest centimeter (314.66m), which is ft, but must be rounded to ft because the original measurement was only to centimeter level. Referenced to NAVD88 datum Geocentric (X,Y,Z) Coordinates X - 18, (meters) COMP Y - -4,566, (meters) COMP Z - 4,437, (meters) COMP Ellipsoid height is m Geoid Undulation is m when referenced to GEOID09 Orthometric height is m-(-35.34m)= m

18 Control Point.The horizontal coordinates were established by GPS observations.and adjusted by the National Geodetic Survey in February The datum tag of NAD 83(2007) is equivalent to NAD 83(NSRS2007)..See National Readjustment for more information..the horizontal coordinates are valid at the epoch date displayed above..the epoch date for horizontal control is a decimal equivalence.of Year/Month/Day..The orthometric height was determined by GPS observations and a.high-resolution geoid model using precise GPS observation and.processing techniques..the X, Y, and Z were computed from the position and the ellipsoidal ht..the Laplace correction was computed from DEFLEC09 derived deflections..the ellipsoidal height was determined by GPS observations.and is referenced to NAD 83..The geoid height was determined by GEOID09. ; North East Units Scale Factor Converg. ;SPC WI C - 59, , MT ;SPC WI C - 196, ,028, sft ;UTM 16-4,917, , MT ! Elev Factor x Scale Factor = Combined Factor!SPC WI C x = !UTM x = Explains observation methods and datum references State plane coordinates in both meters and feet, UTM coordinates, scale factor, and convergence (units in DMS) Combining horizontal and elevation scale factors