'High resolution orthorectified images combine the image characteristics of an aerial photograph with the geometric qualities of a map. An orthoimage is a uniform-scale image where corrections have been made for feature displacement such as building tilt and for scale variations caused by terrain relief, sensor geometry, and camera tilt. A mathematical equation based on ground control points, sensor calibration information, and a digital elevation model is applied to each pixel to rectify the image to obtain the geometric qualities of a map. A digital orthoimage may be created from several photographs mosaicked to form the final image. The source imagery may be black-and-white, natural color, color infrared, or color near infrared (4-band) with a pixel resolution of 1-meter or finer. With orthoimagery, the resolution refers to the distance on the ground represented by each pixel. '

'High resolution orthorectified images combine the image characteristics of an aerial photograph with the geometric qualities of a map. An orthoimage is a uniform-scale image where corrections have been made for feature displacement such as building tilt and for scale variations caused by terrain relief, sensor geometry, and camera tilt. A mathematical equation based on ground control points, sensor calibration information, and a digital elevation model is applied to each pixel to rectify the image to obtain the geometric qualities of a map. A digital orthoimage may be created from several photographs mosaicked to form the final image. The source imagery may be black-and-white, natural color, color infrared, or color near infrared (4-band) with a pixel resolution of 1-meter or finer. With orthoimagery, the resolution refers to the distance on the ground represented by each pixel. '

(Read More) 2008 Orthophoto - This document describes the processes used to create the orthoimagery data produced for the District of Columbia from 2008 digital aerial photography. THE OUTER PARTS DC WERE CAPTURED WITH LEAF-OFF CONDITIONS IN MARCH 2008. HOWEVER, FLYING RESTRICTIONS AND WEATHER DELAYED THE REMAINING AERIAL PHOTOGRAPHY CAPTURE UNTIL MAY 24, 2008 FOR CENTRAL DC. THERE ARE VISIBLE LEAF-ON AND LEAF-OFF SEAM LINES IN THE AERIAL ORTHOPHOTO. The project area covers the entire District of Columbia which is approximately 69 square miles. The digital imagery was used to create natural color digital orthophotography with 16cm pixel resolution. The final orthophotography deliverable products for this project consist of 328 ortho tiles at a scale of 1 to 2400. The tile dimensions are 800 meters by 800 meters. A corresponding MrSid image was created by mosaicking the 328 ortho tiles together and compressing the image using an 80 to 1 compression ration.