Greg Desmond
200710
High Accuracy Elevation Data - truck
text files, shapefiles
http://sofia.usgs.gov/exchange/desmond/desmondelev.html
The High Accuracy Elevation Data Project collected elevation data (meters) on a 400 meter topographic grid with a vertical accuracy of +/- 15 centimeters to define the topography in South Florida. The data are referenced to the horizontal datum North American Datum 1983 (NAD 83) and the vertical datum North American Vertical Datum 1988 (NAVD 88). The High Accuracy Elevation Data Project began with a pilot study in FY 1995 to determine if the then state-of-the-art GPS technology could be used to perform a topographic survey that would meet the vertical accuracy requirements of the hydrologic modeling community. The initial testing platform was from a truck and met the accuracy requirements. Data were collected in areas near Homestead, Florida. The data are available for the areas shown on the USGS High Accuracy Elevation Data graphic at http://sofia.usgs.gov/exchange/desmond/desmondelev.html.
These data are from topographic surveys to collect and provide elevation data to parameterize hydrologic and ecological numerical simulation models that were being developed for ecosystem restoration activities. Surveying services were also rendered to provide vertical reference points for numerous water level gauges.
Modeling of sheet flow and water surface levels in the wetlands of South Florida is very sensitive to changes in elevation due to the expansive and extremely low relief terrain. Hydrologists have determined minimum vertical accuracy requirements for the elevation data for use as input to hydrologic models. As a result, elevation data with a vertical accuracy specification of +/-15 centimeters (cm) relative to the North American Vertical Datum of 1988 (NAVD88) were collected in critical areas using state-of-the-art differential global positioning system (GPS) technology and data processing techniques.
1995
1996
ground condition
As needed
-80.625
-80.25
25.625
25.375
none
High accuracy elevation data
mapping
digital elevation data
DEM
ISO 19115 Topic Category
elevation
006
Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions, Federal Information Processing Standard (FIPS) 10-4, Washington, DC, National Institute of Standards and Technology
United States
US
U.S. Department of Commerce, 1987, Codes for the identification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standard 5-2): Washington, DC, NIST
Florida
FL
Department of Commerce, 1990, Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas, FIPS 6-3, Washington, DC, National Institute of Standards and Technology
Miami-Dade County
USGS Geographic Names Information System
Goulds
Perrine
Grossman Hammock
Royal Palm Ranger Station
none
South East Coast
none
None. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data.
Bob Glover
U.S. Geological Survey
mailing address
521 National Center
Reston
VA
20192
USA
703 648-5056
rglover@usgs.gov
http://sofia.usgs.gov/exchange/desmond/desmondelev.html
USGS High Accuracy Elevation Data
GIF
http://sofia.usgs.gov/exchange/desmond/atlas/
USGS HAED Electronic Atlas (view data by USGS 24K topographic quads)
GIF
Data collection done by Charles Henkle, Gordon Shupe, Bob Glover, Ed Cyran, and Greg Desmond of the USGS and contractors. Other project personnel include Vince Caruso, Gary Freeman, and Susan Price.
compressed ESRI shapefile (.zip) and comma-separated value file (.csv)
Grossman Hammock and Royal Palm Ranger Station are included in both the helicopter AHF & airboat and truck datasets
All verified and accepted data points are included in the files for each area
Horizontal positions are established by GPS observations and are referenced to the North American Datum of 1983 (NAD83). The desired horizontal accuracy is +/- 15 centimeters. This level of accuracy is consistent with GPS differential techniques which use two stations - a high-quality dual-frequency GPS receiver base station and a roving GPS station. The density and accuracy of a given GPS data observation varies from a few meters to a few centimeters according to the Position Dilution of Precision (PDOP) in the study area. Generally if the PDOP is observed to be excessive, data collection is discontinued or the data are discarded. The PDOP is an indicator of the positional accuracy of the GPS that be can derived from the current GPS satellite geometry, which varies continuously. Generally the smaller the PDOP number, the higher the data quality. The PDOP is a permanent part of the recorded data and is also included in the post processing procedures during reduction of the GPS observations to NAD 83. Where possible, the GPS base station has an ellipsoid height to an accuracy of two centimeters relative to the Continuously Operating Reference Stations (CORS) or the High Accuracy Reference Network (HARN), both operated by the National Geodetic Survey (NGS).
For all elevation data the vertical accuracy specification is +/- 15 centimeters and is referenced to NAVD 1988.
This elevation data is intended primarily for use in hydrological modeling. It is collected as high accuracy, "bare earth" ground elevation. That is, the data are restricted to ground elevations only. "Bare earth" in the Everglades swamp environment is generally considered to be the layer of "muck" which will support a one pound weight on a bearing surface of approximately 5.3 square inches (2.6 inch circle). In non-swamp areas it is actual bare ground.
The process for creating digital elevation files consisted of the following steps:
1. Collection of GPS XYZ points in map area 3 during the pilot study started in FY 1995.
2. The GPS data were transformed from NAD83 geographic X, Y coordinates and NAVD88 elevation Z valuse to NAD83 UTM X, Y and NAVD88 Z coordinates via "Corpscon for Windows" from the U.S. Army Corps of Engineers.
http://crunch.tec.army.mil/software/corpscon/corpscon.html
3. The coordinate data were imported into a geographic information system to create multiple geospatial data formats.
4. The ascii text file containing 1925 data records was aggregated and reformatted using custom shell scripts.
5. The shapefile-associated .dbf file was opened in MS Excel and saved as the comma-separated value file which also is available for download
200708
Susan D. Price
U.S. Geological Survey
mailing address
521 National Center
Reston
VA
20192
USA
703 648 6692
sprice@usgs.gov
south east coast of Florida
Vector
Entity point
1925
Universal Transverse Mercator
17
0.9996
-81
0
500000
0
Coordinate Pair
400
400
meters
North American Datum of 1983
Geodetic Reference System 80
6378137
298.257
North American Vertical Datum of 1988
.01
meters
Explicit elevation coordinate included with horizontal coordinates
ELEV_M
ground surface elevation in meters
USGS
X_UTM
UTM X coordinate in meters for the data collection point
USGS
Y_UTM
UTM Y coordinate in meters for the data collection point
USGS
QUAD_NAME
The name of the USGS 1:24, 000-scale topographic quadrangle in which the point falls
USGS
SUR_METHOD
type of surveying method - truck
USGS
Heather S.Henkel
U.S. Geological Survey
mailing address
600 Fourth St. South
St. Petersburg
FL
33701
USA
727 803-8747 ext 3028
727 803-2030
hhenkel@usgs.gov
Truck
No warrantees are implied or explicit for the data
ASCII
1985
.csv
comma-separated values for elevations in map area 3
0.08
http://sofia.usgs.gov/exchange/desmond/desmondelev.html
Files may be downloaded from the SOFIA website
zip
unknown
shp.zip
ArcGIS shapefile and associated files for the elevations collected by truck
file must be unzipped before use
0.051
http://sofia.usgs.gov/exchange/desmond/desmondelev.html
Data may be downloaded from the SOFIA website
none
20071024
Heather Henkel
U.S. Geological Survey
mailing and physical address
600 Fourth Street South
St. Petersburg
FL
33701
USA
727 803-8747 ext 3028
727 803-2030
sofia-metadata@usgs.gov
Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998