FLORIDA GEOGRAPHIC DATA LIBRARY DOCUMENTATION

TITLE: U.S. GEOLOGICAL SURVEY NATIONAL ELEVATION DATASET 

Geodataset Name:       NED    
Geodataset Feature:    GRID
GENERAL DESCRIPTION: 




This dataset contains the U.S. Geological Survey National Elevation Dataset (NED) for the state of Florida.






DATA SOURCE(S):                    U.S. Geological Survey (USGS), EROS Data Center
SCALE OF ORIGINAL SOURCE MAPS:     N/A
DATE OF AUTOMATION OF SOURCE:      1999
GEODATASET EXTENT:                 State of Florida

FEATURE ATTRIBUTE TABLES: 

Datafile Name: NED.VAT
ITEM NAME WIDTH TYPE
OBJECTID
4 OID
VALUE
0 Integer
COUNT
0 Double

FEATURE ATTRIBUTE TABLES CODES AND VALUES:

Item

Item Description





OBJECTID

Internal feature number.
















VALUE

Cell value: equals actual elevation
















COUNT

Number of cells for each value
















USER NOTES:







GeoPlan relied on the integrity of the attribute information within the original data.












The NED is a seamless mosaic of best-available elevation data. The 7.5-minute elevation data for the conterminous United States are the primary initial source data. In addition to the availability of complete 7.5-minute data, efficient processing methods were developed to filter production artifacts in the existing data, convert to the NAD83 datum, edge-match, and fill slivers of missing data at quadrangle seams. One of the effects of the NED processing steps is a much-improved base of elevation data for calculating slope and hydrologic derivatives. The specifications for the NED 1 arc second and 1/3 arc second data are: Geographic coordinate system Horizontal datum of NAD83, except for AK which is NAD27 Vertical datum of NAVD88, except for AK which is NAVD29 Z units of meters.


Only 24 Metadata records are currently included in the Dynamic Metadata. The bounding coordinates requested include more than 24 records so this metadata is the generic metadata for the whole dataset.













A note concerning data scale:

Scale is an important factor in data usage. Certain scale 
datasetsare not suitable for some project, analysis, or
modelling purposes. Please be sure you are using the best
available data.

1:24000 scale datasets are recommended for projects that 
are at the county level.

1:24000 data should NOT be used for high accuracy base 
mapping such as property parcel boundaries.

1:100000 scale datasets are recommended for projects that 
are at the multi-county or regional level.

1:250000 scale datasets are recommended for projects that 
are at the regional or state level or larger.

Vector datasets with no defined scale or accuracy should 
be considered suspect. Make sure you are familiar with 
your data before using it for projects or analyses. Every 
effort has been made to supply the user with data 
documentation. For additional information, see the 
References sectionand the Data Source Contact section of 
this documentation. For more information regarding scale 
and accuracy, see our web pages at:

http://www.geoplan.ufl.edu/education.html






REFERENCES: 






U.S. Geological Survey:
http://gisdata.usgs.net/ned/







DATA LINEAGE SUMMARY: 









The 7.5-minute elevation data for the conterminous United States are the 
primary initial source data. In addition to the availability of complete 7.5-minute 
data, efficient processing methods were developed to filter production artifacts 
in the existing data, convert to the NAD83 datum, edge-match, and fill slivers 
of missing data at quadrangle seams.
Process Date: Unknown


Counties with high pixel values:

1. Clay (ned10)
	range 0-90
	2 pixels = 255

2. Duval (ned16)
	range 0-57
	3 pixels = 255

3. Escambia (ned17)
	range 0-103
	12 pixels = 254
	110 pixels = 255

4. Layfayette (ned34)
	range 0-55
	7 pixels = 255

5. Pinellas (ned52)
	range 0-30
	1 pixel = 255

6. Santa Rosa (ned57)
	range 0-90
	2 pixels = 254
	22 pixels = 255

The six counties with abberrant values were processed to 
eliminate the spikes in the data. Each GRID was visually 
inspected to identify where the pixel values of 255 were 
located.  In each GRID, the high values were in the ocean 
and were surrounded by pixel values of zero on each side.  
Therefore, the pixel values of 255 were reclassified to zero.

Counties with an irregular area:
(looks like higher resolution quads)

1. Calhoun (ned07)

2. Dixie (ned15)

3. Gilchrist (ned21) 

4. Layfayette (ned34)

5. Madison (ned40)

6. Suwannee (ned61)
Process Date: 20030000









MAP PROJECTION PARAMETERS: 



Projection                          ALBERS
Datum                               HPGN
Units                               METERS
Spheroid                            GRS1980
1st Standard Parallel               24  0  0.000
2nd Standard Parallel               31 30  0.000
Central Meridian                   -84 00  0.000
Latitude of Projection's Origin     24  0  0.000
False Easting (meters)              400000.00000
False Northing (meters)             0.00000




DATA SOURCE CONTACT (S):








Name:
Abbr. Name:
Address:


Phone:

Web site:
E-mail:
Contact Person:
         Phone:
        E-mail:




EROS Data Center
USGS NED
U.S. Geological Survey EROS Data Center
Sioux Falls, SD
57198
605-594-6151


http://gisdata.usgs.net/ned/
custserv@edcmail.cr.usgs.gov
Customer Services Representative







FGDL CONTACT:

Name:                   FLORIDA GEOGRAPHIC DATA LIBRARY
Abbr. Name:             FGDL
Address:                Florida Geographic Data Library
                        431 Architecture Building
                        PO Box 115706
                        Gainesville, FL  32611-5706
Web site:               http://www.fgdl.org

Contact FGDL: 

      Technical Support:	        http://www.fgdl.org/fgdlfeed.html
      FGDL Frequently Asked Questions:  http://www.fgdl.org/fgdlfaq.html
      FGDL Mailing Lists:		http://www.fgdl.org/fgdl-l.html
      For FGDL Software:                http://www.fgdl.org/software.html