2014 NOAA Ortho-rectified Color Mosaic of Hurricane Sandy Coastal Impact Area: Stonington, CT to Westport, MA

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Digital aerial imagery was obtained using a large format Z/I Digital Mapping Camera system (DMC) equipped with Airborne GPS/IMU covering the AOI. A total of 9 flight lines with 239 frames were collected in fall 2014 in multi-spectral (RGB and NIR) 16 bits per band format. The imagery was acquired with a 120mm focal length at an altitude above mean terrain of 3,360' to yield a raw pixel resolution of 0.35m. The imagery was collected during leaf off conditions in early 2014 under conditions free from clouds and cloud shadows, smoke, fog, haze, light streaks, snow, ice on water bodies, foliage, flooding, and excessive soil moisture. The sun angle threshold was 30 degrees. The imagery consisted of panchromatic, blue, green, red and near infrared bands. The three color bands and near infrared bands have been pan sharpened and archived as frame imagery. Ground based photo control points were established throughout the area of interest using a combination of conventional and GPS survey methods in order to support softcopy aerotriangulation and photogrammetric mapping meeting the accuracies specified in this Scope of Work. This control supplemented the exposure station control obtained from the onboard Airborne Global Positioning System (ABGPS) and Inertial Measurement Unit (IMU). Photo control points established for this project have a combined local and network accuracy at 95% confidence of less than or equal to five (5) centimeters horizontally and vertically as determined by the residuals of the network adjustment. Utilizing all four pan-sharpened bands [blue (B), green (G), red(R) and near infrared (IR)] digital orthorectification was performed using cubic convolution algorithms resulting in a spatial and radiometric transformation of the digital image from line/sample space into UTM Zone 19. The interior and exterior orientation parameters were used to project each pixel into the ground coordinate system, while the ortho grade DEM/DTM was used to correct for relief displacement. Radiometric correction software and techniques were used to create orthophoto files that minimize the appearance of image seams and without loss of feature signature. Orthophotos are checked for geometric accuracy, image quality and tonally balanced to produce a uniform contrast and tone across the entire project. The individual overlapping orthophoto frames were mosaicked together and the final tiles were extracted from the image set to a 1,400 x 1,400 meter tiling scheme consisting of 269 individual ortho tiles. Delivery included digital ortho photos at a 0.35m pixel ground sample distance in 8 bit, 4 band (RGB and NIR) uncompressed GeoTIFF. The ortho photos meet a horizontal accuracy of +/- 1 meter or less RMSE when compared to higher accuracy check points based on NSSDA testing standards.