Pennsylvania 1993 Orthoimagery

U.S. Geologic Survey, Pennsylvania Bureau of Topographic and Geologic Survey

Data Source


Orthophotos combine the image characteristics of a photograph with the geometric qualities of a map. The primary digital orthophotoquad (DOQ) is a 1-meter ground resolution, quarter-quadrangle (3.75-minutes of latitude by 3.75-minutes of longitude) image cast on the Universal Transverse Mercator Projection (UTM) on the North American Datum of 1983 (NAD83).The geographic extent of the DOQ is equivalent to a quarter-quad plus The overedge ranges a minimum of 50 meters to a maximum of 300 meters beyond the extremes of the primary and secondary corner points. DOQ images are acquired as a part of the USGS’ National Aerial Photography Program (NAPP). Through NAPP imagery for each state is produced on a 7 year cycle. These images are the NAPP III cycle which will run from 1997-2001. These DOQQ’s are distributed through PASDA as GeoTIFF images as received from USGS.


Pennsylvania Spatial Data Access (PASDA)U.S. Geologic Survey, Pennsylvania Bureau of Topographic and Geologic Survey

Horizontal Positional Accuracy

The DOQ horizontal positional accuracy and the assurance of that accuracy depend, in part, on the accuracy of the data inputs to the rectification process. These inputs consist of the digital elevation model (DEM),aerotriangulation control and methods, the photo source camera calibration, scanner calibration, and aerial photographs that meet National Aerial Photography Program (NAPP) standards. The vertical accuracy of the verified USGS format DEM is equivalent to or better than a USGS level 1 or 2 DEM, with a root mean square error (RMSE) of no greater than 7.0 meters. Field control is acquired by third order class 1 or better survey methods sufficiently spaced to meet National Map Accuracy Staandards (NMAS) for 1:12,000-scale products. Aerial cameras have current certification from the USGS, National Mapping Division, Optical Science Laboratory. Test calibration scans are performed on all source photography scanners.

Access/Use Constraints

Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from these data.

Distribution Liability

The USER shall indemnify, save harmless, and, if requested, defend those parties involved with the development and distribution of this data, their officers, agents, and employees from and against any suits, claims, or actions for injury, death, or property damage arising out of the use of or any defect in the FILES or any accompanying documentation. Those parties involved with the development and distribution excluded any and all implied warranties, including warranties or merchantability and fitness for a particular purpose and makes no warranty or representation, either express or implied, with respect to the FILES or accompanying documentation, including its quality, performance, merchantability, or fitness for a particular purpose. The FILES and documentation are provided “as is” and the USER assumes the entire risk as to its quality and performance. Those parties involved with the development and distribution of this data will not be liable for any direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the FILES or any accompanying documentation.

Although these data have been processed successfully on a computer system at the U.S. Geological Survey no warranty expressed or implied is made by the USGS regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. The USGS will warrant the delivery of this product in computer-readable format and will offer appropriate adjustment of credit when the product is determined unreadable by correctly adjusted computer input peripherals, or when the physical medium is delivered in damaged condition. Requests for adjustments of credit must be made within 90 days from the date of this shipment from the ordering site.

Map software is provided ‘as-is’, without any express or implied warranty. In no event will be held liable for any damages arising from the use of this software. The user assumes all risks associated with the use of this software. will not be held responsible for any inaccuracies and no responsibility is assumed for damages or other liabilities due to errors, installation, accuracy, availability, use or misuse of the data presented.

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Downloadable Version for Offline Use

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