Horry County South Carolina Orthophotography

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TerraSurv was contracted by the Fugro EarthData to acquire 16 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. | Type of Source Media: external hard drive

In 2006 Sanborn flew lidar data over Horry County South Carolina. The data produced from that project was utilized as the surface for orthorectification. | Type of Source Media: external hard drive

The aerial imagery acquisition for Horry County was flown to support the creation of digital orthophotography with a 15cm pixel. The imagery was acquired on February 16th, 17th, 18th, 19th, 20th, 21st, 26th, March 5th, 6th, and 8th, 2010. There were fourteen sorties and 104 flight lines. All imagery was collected using the PanoramiX digital sensor. | Type of Source Media: not made available

The Digital Orthoimagery is comprised of 8 bit color imagery captured by the PanoramiX camera. Using the Preprocessor software, data was unpacked and indexed. A QA/QC process was performed to ensure integrity of the raw data. An automated radiometric calibration was performed as an initial adjustment to aid in creating consistent imagery. GPS data captured during flight was processed and integrated into the project, after which a block solution was calculated in the Dataviewer software. A QA/QC process was performed on this solution to identify any anomalies. This was done by reconstructing various points in the solution. Ground Control was imported into the Dataviewer software and measured in order to refine the solution. The surface model from the 2009 Horry County project, with some updated areas, was imported into the Dataviewer software. The imagery was then rectified for each flight line using the refined block solution and the imported surface model. A QA/QC process was performed to check for any rectification errors. The rectified imagery was exported from the Dataviewer software along with a reduced resolution mosaic, or Quicklook, of each of these imagery strips. The quicklooks were radiometrically adjusted using Earthdata Proprietry software and then imported into the Pixel Factory software along with the full resolution mosaic flight lines. The histogram from the quicklook was applied to the full resolution imagery. Mosaic lines were placed, joining the 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 was removed from the Pixel Factory environment in a process called "packaging" where the individual tiles are created. 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 imagery is then Projected to the appropriate co-ordinate system and recut to the tiling scheme required for delivery. The final digital ortho product was GEOTIFF files. All data was delivered on external hard drives.