2004 Florida Greenway ADS40 Orthoimagery and Digital Elevation Model

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Custom download app for the DEM.

download of color infrared imagery files

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Date that the source FGDC record was last modified.

Converted from FGDC Content Standard for Digital Geospatial Metadata (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details.

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The aerial imagery acquisition for the Florida Greenway Corridor was flown to support the creation of digital orthophotography with a 50 centimeter pixel. The imagery was acquired in four sorties at 15,700 feet AMT, using the Leica ADS40 sensors, SP14. | Type of Source Media: external hard drive

Terrasurv Inc. was contracted by EarthData to provide survey services in the NW Greenway located in Bay, Calhoun, Franklin, Gulf, Walton and Washington Counties, Florida. Digital aerial imagery (Leica ADS-40) observations were made for the project.Terrasurv utilized the Global Positioning System (GPS) to establish the control network. 1) The photo control stations were established post flight; therefore all new stations are photo-identifiable points. No permanent stations were set. There were a total of 25 new photo identities established. In addition, there were 3 temporary base points and the airborne GPS (ABGPS) base station used by the flight crew. 2) 17 additional photo identities were obtained in December of 2005 to support the reflight of several flight lines. | Source Geospatial Form: model | Type of Source Media: paper

Photogrammetrically compiled DTM was used for the bare earth ground elevation dataset deliverable of this project. A gridded, DEM was derived from this dataset to rectify the orthophotography for this project. Stereo imagery generated from the ADS40 flight data was used for the photogrammetric collection. The scale of the sources was 30 meter and 2 meter grids. | Source Geospatial Form: map | Type of Source Media: external hard drive

The airborne GPS data were processed and integrated with the IMU. The results were imported into the ISTAR system for use in the aerotriangulation. The ADS40 imagery was downloaded onto the EarthData server and brought over to the UNIX based ISTAR system. The ground control was used in conjunction with the processed ABGPS results for the aerotriangulation. The properly formatted ISTAR results were used for subsequent processing.

This process describes the import and QC of the photogrammetrically-derived DEM surface from stereo pairs for use in the ISTAR processing system. 1. Using the DEM data set, the technician performed a visual inspection of the data to verify that the flight lines met correctly. The technician also verified that there were no voids, and that the data covered the project limits. The technician then selected a series of areas from the dataset and inspected them where adjacent flight lines met. A process, which utilizes 3-D Analyst and EarthData's proprietary software was run to detect and color code the differences in elevation values and profiles. The technician reviewed this information and located the areas that contained systematic errors or distortions that were introduced by the auto correlation. 2. Systematic distortions highlighted in step 1 were removed and the data were re-inspected. Corrections and adjustments can involve the application of angular deflection or compensation for curvature of the ground surface that can be introduced by crossing from one type of land cover to another. 3.The data were checked against the control network to ensure that vertical requirements were maintained.

The digital orthophotography is comprised 50 centimeter pixel Ground Orthos. Once the DEM data was integrated into the ISTAR system the initial radiometric adjustments were performed on the imagery for each flight line attempting to reach the best possible histogram. The rectification process was run using the processed DEM surface and the radiometrically balanced imagery on each flight line. A second set of radiometric adjustments were made and mosaic lines were placed. QA/QC was performed looking for smears and other indications of problems within the digital orthophoto creation process. The final imagery data set is removed from the ISTAR environment in a process called "packaging" where the individual tiles are created. The created tiles are reviewed again for anomalies and interactive radiometric adjustment applied where needed. The final product was GeoTIFF format digital orthos.