Horry County South Carolina, U.S. Geological Survey (USGS) and Fugro Earthdata, Inc. - ADS40-52 processing completed at Fugro Earthdata's Frederick, MD facility
07152010
Georgetown, Marion, Dillon Counties South Carolina Orthophotography, 17SPS285840
remote sensing image
South Carolina
Horry County South Carolina, U.S. Geological Survey (USGS) and Fugro Earthdata, Inc.
Orthophotos combine the image characteristics of a photograph with the geometric qualities of a map. The primary digital orthophoto is a 30cm GSD resolution with tiles measuring 1500 x 1500 meters cast on the Universal Transverse Mercator Zone 17N on the North American Datum of 1983 (NAD83/2007). The aerial photography used to create the digital images was acquired between January 31st, and February 8th, 2010.
The orthophotography was created for use by the USGS, and Horry County South Carolina.
2010
ground condition
Unknown
-79.619991755
-79.603671353
33.30094130
33.28723543
none
rectified photograph
rectified image
orthophoto
3 band orthophoto
orthoimage
image map
U.S. Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions (Federal Information Processing Standard (FIPS) 10-4): Washington, D.C., National Institute of Standards and Technology.
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 (FIPS) 5-2): Washington, D.C., National Institute of Standards and Technology.
SC
None
South Carolina
All orthophotography is the property of the USGS and Horry County
Orthophotography is the property of the USGS, and Horry County, SC. Orthophotography is the intellectual property of the USGS, and Horry County, SC.
Fugro Earthdata, Inc.
The following software is used for validation of the imagery and surface modeling
1. Aerotriangulation - Pixel Factory
2. Digital Orthophotography - Pixel Factory
3. Bentley - MicroStation
4. Pixel Factory
5. ZI - OrthoPro
6. ESRI - ArcInfo
7. ERDAS Imagine
8. TerraScan
9. Earthdata Proprietary software
10. Adobe - Photoshop
11. GPro
3
red, green, blue
red - band 1, green - band 2, blue - band 3
30cm master metadata
The orthophotos were created to be fully complient with a horizontal positional accuracy shall not exceed 5.19 meters tested to NSSDA Standards (95% confidence). Error XY will not exceed 1.49 m RMSE X or Y.
Compliance with the accuracy standard was ensured by the collection of photo identifiable GPS ground control after the acquisition of aerial imagery. The following checks were performed.
1. The ground control and airborne GPS data stream were validated through a fully analytical bundle aerotriangulation adjustment. The RMSE is less than 1, 10,000th of the flying height.
2. The DSM (DEM) and lidar data were checked against the project control. The technician visited and confirmed the accuracy of the points during initial processing.
3. Digital orthophotography was validated through an inspection of edge matching and visual inspection for image quality.
The following methods are used to assure imagery accuracy.
1. Use of IMU (inertial measurment unit) and ground control network utilizing GPS techniques.
2. Use of airborne GPS (global positioning system) inconjunction with the acquisition of imagery. The following software is used for validation of the imagery and surface modeling.
1. Aerotriangulation - Pixel Factory
2. DSM and DEM data - Pixel Factory
3. Digital Orthophotography - Pixel Factory and Photoshop.
4. Bentley - MicroStation
5. Pixel Factory
6. ESRI - ArcGIS
7. Earthdata proprietary software
8. Adobe - Photoshop
The orthophotos were created to be fully complient with a horizontal positional accuracy shall not exceed 5.19 meters tested to NSSDA Standards (95% confidence). Error XY will not exceed 1.49 m RMSE X or Y.
Horry County South Carolina, U.S. Geological Survey (USGS), and Fugro Earthdata, Inc.
2010
South Carolina raw ADS40-52 data
1200
not made available
2010
ground condition
Aerial Acquisition
The aerial imagery acquisition for Georgetown, Marion, and Dillon Counties was flown to support the creation of digital orthophotography with a 30cm pixel. The imagery was acquired on January 31st, and February 3rd, 7th, and 8th, 2010. There were four sorties and 50 flight lines. All imagery was collected using the Leica ADS40-52 digital pushbroom sensor.
Horry County South Carolina, U.S. Geological Survey (USGS), and Fugro Earthdata, Inc.
2010
Digital Surface Model for Georgetown County
external hard drive
2009
ground condition
Pixel Factory DSM
In 2009 the county of Georgetown tasked Fugro EarthData in 2009 to fly and produce orthophotography. For that project a DSM was generated from Fugro EarthData's Pixel Factory processing software. The Pixel Factory digital surface modeling is based on an auto correlated pixel-matching system within the Pixel Factory software. The auto correlated digital surface model (DSM) surface represents the initial surface model. The following is the process used.
1. Using the DSM Pixel Factory data set created, the technician performed a visual inspection of the data to verify that the flight lines met correctly. The technician also verified that there were no voids, and that the data covered the project
limits. The technician then selected a series of areas from the dataset and inspected them where adjacent flight lines met.
2. This DSM surface is used in the rectification of the orthoimagery.
South Carolina LiDAR Consortium
2009
Lidar Surface
external hard drive
2008
ground condition
lidar
In 2008 Fugro EarthData flew lidar data over Marion and Dillon counties South Carolina for the South Carolina LiDAR Consortium. The data produced from that project was utilized as the surface for orthorectification.
TerraSurv
2010
Ground Control
external hard drive
20100201
20100215
ground condition
photo id ground control
TerraSurv was contracted by the Fugro EarthData to acquire 36 ground control points during the acquisition of aerial imagery. The ground control points were established using GPS for vertical and horizontal coordinate values. NAD83(NSRS2007)South Carolina Stateplane NAVD 88 International Feet.
The digital orthophotography is comprised of a 24 bit, natural color RGB bands, 30cm pixel resolution ground orthos for the 3 counties of the project. The Pixel Factory process was used in the generation of the orthoimagery covering all project tiles. The initial radiometric adjustments were performed on the imagery for each flight line attempting to reach the best possible histogram. The rectification process was then run using the processed DSM and the lidar surfaces and the radiometrically balanced imagery on each flight line. The quicklook (reduced resolution rectification) of each flight line exported out of Pixel Factory. A second set of radiometric adjustments were made using Earthdata proprietary tools. The radiometrically balanced imagery was then re-imported into the Pixel Factory system and the histogram from the quicklook was applied to the full resolution imagery. Mosaic lines were placed, joining the ADS40 imagery strips. In initial QA/QC was performed by the technician to ensure that the mosaic lines were appropriately placed and that there was appropriate imagery coverage. The final imagery data set is removed from the Pixel Factory environment in a process called "packaging" where the individual tiles are created. All data processing in the Pixel Factory system is performed in UTM Zone 17N meters; it is during packaging that final datum and projection are defined. The created tiles are reviewed again for anomalies and interactive radiometric adjustment applied where needed. QA/QC was performed looking for anomalies, smears and other indications of problems within the digital orthophoto creation process, interactive radiometric adjustment applied where needed. Two additional radiometric adjustments are applied to the completed orthos in Adobe Photoshop. The first is a sharpening mask filter; this filter is used to help increase sharpness of a digital image. The basis for this filter is to locate pixels that differ in value from surrounding pixels by the threshold specified. It then increases the pixels contrast by the value identified. For neighboring pixels specified by the threshold, the lighter pixels get even lighter and the darker pixels get even darker based on the specified amount. The changes made maintained the integrity of the original histogram curve. The final digital ortho product was GEOTIFF files. All data was delivered on external hard drives.
20100501
Transverse Mercator
0.999600
-81.000000
0.000000
500000.000000
0.000000
coordinate pair
0.100000
0.100000
meters
D_NAD_1983_NSRS2007
Geodetic Reference System 80
6378137.000000
298.257222
2010
Fugro Earthdata, Inc.
mailing and physical
7320 Executive Way
Frederick
MD
21704
Fugro Earthdata, Inc. - 301.948.8550
FGDC Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998