Pennsylvania/PEMA Orthoimagery
The Pennsylvania Emergency Management Agency (PEMA) is an agency of the Commonwealth of Pennsylvania. It helps communities and citizens mitigate against, prepare for, respond to, and recover from emergencies including natural disasters, acts of terrorism, or other human-made disasters.
Imagery
PEMA Orthoimagery is a data set includes 0.5-foot (15-centimeter) 8-bit 4-band (RGBN) digital orthoimage tiles in GeoTIFF, Mr. SID, and JPEG 2000(JP2) format. The PEMA 0.5-foot Orthoimagery called for the planning, acquisition, processing, and derivative products of imagery data to be collected at a ground sample distance (GSD) of 0.5-foot (15 centimeters). Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Ortho Specification, Version 1.0. The data were developed based on a horizontal projection/datum of NAD83 (2011) State Plane Pennsylvania, US Survey Feet. Orthoimagery data was delivered as 298 individual 0.5-foot (15-centimeter) 1" = 100' GeoTIFF (uncompressed) 10,000-foot x 10,000-foot (3,048-meter x 3,048-meter) tiles. Aerial photography was captured during the spring, while no snow was on the ground and rivers were at or below normal levels. In order to post process the imagery data to meet task order specifications and meet horizontal accuracy guidelines, Quantum Spatial, Inc. utilized a total of 496 QC points throughout the Commonwealth of Pennsylvania to assess the horizontal accuracy of the data. These checkpoints were not used to calibrate or post process the data.
License
PASDA Director Maurie C. Kelly has approved the imagery usage in OpenStreetMap as public domain data. A proof has been obtained and uploaded to the OpenStreetMap Wiki. 
Usage
PEMA Orthoimagery has been included in iD since 2.20.0. If you wish to use this imagery out of iD, please follow the instruction at https://github.com/osmlab/editor-layer-index.