Abstract: This data set is a countywide mosaic of 1:18,000-scale, black & white aerial photos. It was developed by scanning and orthorectifying 440 individual photographs, and combining a subset of the resulting digital images into the mosaic. In addition to the hardcopy photos, the primary data sources used in the photo orthorectification included 1998 1:12,000-scale Digital Orthophoto Quarterquads (DOQs), 1974 1:20,000-scale digital orthophotos, and 30-meter Digital Elevation Models (DEMs). The mosaic is provided in IMAGINE (*.img/.ige) format. A MrSID (*.sid) version of the mosaic is also available, but image quality may be poorer due to the compression applied. The 440 individual orthophotos, in .tif format, are also available. The normal orientation of the data is by lines (rows) and samples (columns). Each line contains a series of pixels ordered from west to east with the order of the lines from north to south. The radiometric image brightness values are stored as 256 gray levels ranging from 0 to 255. Note that sections of this metadata record, in particular the Data Quality section, describe the processing performed on the individual photos used to generate the mosaic.
Purpose: This mosaic of historic orthophotography provides a visual perspective of the landscape in the early 1960's. Due to its geometric qualities, it is useful as a reference layer in a geographic information system, and provides a valuable tool for land use mapping and change analysis.
Supplemental Information: Data distribution tile: county

Progress: Complete
Update Frequency: None planned

Theme Keywords: None, Digital orthophoto, Digital image map, Aerial photograph, Rectified photograph, Rectified image, Orthophoto, Historic
Place Keywords: United States, Northeast, New England, New Hampshire, Rockingham County

Access Constraints: Acknowledgement of GRANIT is appreciated in products derived from these data.
Usage Constraints: Not for legal use