2013 Athens-Clarke County, Georgia Imagery

This data set consists of 0.5 foot pixel resolution, four band (RGB, Near IR) orthoimages covering Athens-Clarke Georgia. An orthoimage is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthoimagery combines the image characteristics of a photograph with the geometric qualities of a map. The design accuracy is estimated not to exceed +/- 2.5 feet CE95 of the position on the ground. Each orthoimage provides imagery over a 5,000-foot by 5,000-foot block on the ground. There is no image overlap between adjacent files. The projected coordinate system is State Plane GA West (FIPS 1002) with a NAD83 Datum and units are a US Foot. The Athens-Clarke County's and Statewide Georgia tiling schemas was used.

This data depicts geographic features on the surface of the earth. It was created to provide easily accessible geospatial data which is readily available to enhance the capability of Federal, State, and local emergency responders, as well as plan for homeland security efforts. This data also supports impervious surface mapping.

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Four band orthoimagery is organized in four color bands or channels which represent the red, green, blue (RGB) and Near Infrared (NIR) portions of the spectrum. Each image pixel is assigned a quadruplet of numeric values, one for each color band. Numeric values range from 0 to 4096. Areas where data is incomplete due to lack of full image coverage are represented with the numeric value of 0.

NOAA - OCM Contract

Woolpert prepared the original data as set forth in the Scope of Services, in accordance with reasonable care and due diligence as set forth in this Agreement, however, due to the easily alterable nature of electronic media, files, documents, and other deliverables, Woolpert, Inc. makes no warranties, either expressed or implied, with respect to the accuracy, completeness, merchantability, or fitness for any particular purpose, including, but not limited to, use of any/all data as described within this metadata file, by any user of this data. Any use will be at the end-user's sole risk.

https://coast.noaa.gov/dataviewer. This data set is dynamically generated based on user-specified parameters.;

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None. However, users should be aware that temporal changes may have occurred since this data set was collected and that some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of it's limitations. Acknowledgment of the NOAA-Office for Coastal Management would be appreciated for products derived from these data.

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Intergraph's suite of digital mapping and orthorectification software; Microstation; ArcGIS

Radiometry is verified by visual inspection of the digital orthophoto. Slight systematic radiometric differences may exist between adjacent orthoimage files; these are due primarily to differences in source image capture dates and sun angles along flight lines. These differences can be observed in an image's general lightness or darkness when it is compared to adjacent orthoimage file coverages. Tonal balancing may be performed over a group of images during the mosaicking process which may serve to lighten or darken adjacent images for better color tone matching.

Orthoimagery is designed to meet or exceed +/- 2.5 feet CE95.

Orthoimages are visually inspected for completeness to ensure that no gaps or image misplacements exist within and between adjacent images. These images are derived by mosaicking multiple images to ensure complete coverage. Source imagery is cloud free. Photography was flown during leaf-off in deciduous vegetation regions. Voided areas have a radiometric value of either zero (black) or 128 (uniform gray).

All GeoTIFF tagged data and image file sizes are validated using commercial GIS software to ensure proper loading before being archived. This validation procedure ensures correct physical format and field values for tagged elements. Seamlines and tile edges are visually inspected. Seamline mismatches are not corrected unless the overall displacement exceeds one meter.