Data Management Plan

The NOAA Office for Coastal Management purchased digital ADS40 imagery and digital elevation models of the Connecticut coastline in 2004. The Coastal Connecticut project area is comprised of approximately 930 square miles. A total of 244 orthos (122 natural color and 122 color infrared) were produced to cover this area. Aerial imagery was collected in panchromatic, Red, Green, Blue and Near Infrared which yielded a natural color and false color infrared version of the completed digital orthophotography. In addition to producing the digital ortho imagery a first surface (reflective surface) elevation data set was produced. Imagery was collected at an approximate altitude of 15,750 feet above mean terrain.

Original contact information:

Contact Name: Harold Rempel

Contact Org: EarthData International, Inc.

Title: Director of Program Management

Phone: 301-948-8550

Email: hrempel@earthdata.com

Process Steps:

• 2004-12-23 00:00:00 - Source Imagery - ADS40 Digital Camera Imagery. Control - Airborne GPS/IMU supplemented with photo identifiable field control Aerotriangulation - X software package Elevation Model - X software package Radiometric Balancing - X software package and COTS Software (PhotoShop). Orthorectification - X software package. Mosaic - X software package and Z/I Imaging OrthoPro software package. The following section describes the X digital image production sequence. This is a mature, stable workflow and incorporates all production components into an integrated series of tools to accomplish photogrammetric mensuration, aerotriangulation, elevation model development, ortho production and finishing. Production processes are fully documented in accordance with ISO9001 mandates. The following is a step-by-step description of the X workflow to develop digital orthophoto quarter quads to. Step 1 The unprocessed ADS40 data and accompanying GPS and IMU data for one or more sorties was downloaded from the portable hard disks and checked to verify that no files were corrupted and that all data could be downloaded. Digital aerial imagery that was used for this project includes the Red, Green, Blue, Near Infrared channels as well as the S1 pan, S2 pan and nadir green channels. Sample segments of the imagery were inspected in an uncorrected state to verify the integrity of each data sortie. Step 2 The GPS/IMU parameters for each sortie were optimized using the ground control points and the error calibration map. The horizontal and vertical positions of all ground control points in the block were observed in each channel (R,G,B, IR, R, G, S1 Pan, S2 Pan). Step 3 Aerotriangulation was accomplished using the CLB tool that is a component of the X process.
• 2004-12-23 00:00:00 - The ground control, GPS and IMU information were ingested and tie points between strips were identified. Normally, only 3 tie points are needed between adjacent flight lines. Step 4 CLB produces a bundle adjustment for each data sortie. The results of the adjustment were verified through the development of a sub-sampled panchromatic mosaic for the data sortie. The mosaic was corrected using the aerotriangulation points only. This mosaic was inspected by the photogrammetric technician to identify any gross errors in the adjustment as well as the identification of any voids or image quality problems. Step 5 Using several tools that are part of the ISTAR workflow, a digital surface model (DSM) is correlated at a post spacing of 2 meters depending on terrain and land cover. The ISTAR correlation algorithm computes the X,Y,Z value for each DSM post utilizing every stereo angle that is available. A series of DSM files are created for acquisition block, one for each stereo look angle. A mosaic is then created from the separate DSM files where the best vertical value for each posting is selected from all look angles compared against the aerotriangulation adjustment which is incorporated into the mosaic. Company X will then edit the surface to the level required to support the orthophoto production. Step 6 The digital imagery for each acquisition sortie was differentially rectified to produce digital orthophoto mosaics in natural color and false color infrared renditions at a resolution of 0.50-meter per pixel. The orthophoto mosaics were inspected for accuracy issues that fall in the following categories - - Aerotriangulation related - DSM related Accuracy issues were investigated through review and correction of the DEM or triangulation adjustment. Once the imagery passed quality control review, final radiometric adjustments were performed to create a uniform overall appearance. The final DOQQ tiles were organized for nominal 3.75 by 3.75 minute areas corresponding to the USGS quarter quad boundaries and were clipped out with the specified overage of a minimum of 30 meters beyond the quarter quad boundaries. Imagery was output in the following formats - 24-bit natural color GeoTIFF images 24-bit false color infrared GeoTIFF images Step 7 The completed digital orthophotos were checked for image quality. Minor artifacts were corrected using Adobe Photoshop in an interactive editing session. Digital files were assigned final names based on the National Grid. Step 8 Project level metadata describing the orthophoto production process was developed to support the task.