2002/2003 IfSAR data for Southern California: Digital Elevation Model (NAVD88)

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Converted from FGDC Content Standards 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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NOAA Coastal Service Center obtained the final product deliverable from EarthData International, processed it, and loaded it into ArcSDE for distribution purposes. | Type of Source Media: Digital

The project was flown using EarthData's modified Gulfstream-II jet aircraft. The IfSAR data was captured using a dual-frequency, dual-polarimetric, Interferometric airborne radar mapping system (GeoSAR) that generates digital elevation models (DEMs) and orthorectified radar reflectance maps near the tops of trees as well as beneath foliage. Data was captured simultaneously in both X-band (first surface, near the tops of trees) and P-band (beneath the foliage). X-band antenna are mounted under the wings close to the fuselage and have a 160 MHz bandwidth at a center frequency of 9.7 GHz. P-band antennas are mounted on the wingtips and have a center frequency of 350 MHz. Each X-band and P-band antenna provides two looks at each point on the ground for a total of four looks on each side. Flight lines are overlapped to provide coverage of the space directly beneath the aircraft. As a result, some points on the ground are covered eight times. Left-right look angles on each side of the aircraft combined with mosaicking process mitigates radar shadow and layover. X-band data has been processed for the entire project area and P-band has been processed for an area of approximately 300 square kilometers within the project area. Due to flight clearance requirements all data was normally collected between the hours of 10 PM and 7 AM. | Source Geospatial Form: model | Type of Source Media: Digital data tape

Ground control and GPS base station locations were established to provide the necessary control to meet the accuracy requirements of the project. Radar reflective corner reflectors were deployed across the project area to be used in the mosaicking stage to ensue that the data met the accuracy requirements. A total of fourteen reflectors were deployed across the total project area with six reflectors deployed within the Phase I project area. A total of ten additional ground control points were established using GPS for vertical and horizontal coordinate values. These points were used during the quality control process to evaluate the accuracy of the final mosaicked data. Ground control references UTM Zone 11, NAD83, GRS80. | Source Geospatial Form: model | Type of Source Media: Paper/digital

EarthData has developed an in depth production process for processing GeoSAR data to meet NOAA's specifications. The following outlines the GeoSAR acquisition and processing workflow that was designed to produce the final product deliverables. 1. PROJECT PLANNING. The success of this project depended on effective management of all components of the project. To support this effort EarthData identified an experienced management team to oversee all aspects of the project. This team was responsible for ensuring that all project requirements outlined in the SOW and any subsequent amendments were met and that an open communication/reporting line was maintained with all participants. 2. GeoSAR ACQUISITION AND PROCESSING WORKFLOW. This section describes the general workflow for the GeoSAR system for the planning, collection, processing, and mosaicking of GeoSAR dual band IFSAR products. 2.1 Collection & Processing Requirements Production Steps Six major activities take place in this production step. A. Ground Control requirements are derived from the Project accuracy and QC specification in combination with the data take flight lines. The need for in situ corner reflectors, kinematic GPS profiles, and mosaicking control drive this task. B. Kinematic GPS is routinely specified for collection (where cost effective) to provide an independent means of quickly verifying the end mosaic product. This is an important part of the overall QA process, since this data is sequestered from the mosaicking staff until after the mosaic is completed. Kinematic GPS data is frequently collected prior to deployment in conjunction with the site survey (see item-D, below). C. GPS Base Station Location candidate sites are selected from the existing High Accuracy Regional Networks (HARN) in the project area, and the High Precision Geodetic Net (HPGN) in California. One or more such locations are usually occupied as the base stations during the flight mission. If such a station is not available within or close to the project site, then either an existing HPGN densification station is used or a new station is established through static GPS survey connected to HPGN stations and meeting the FGCS Order-C, Class-I relative positioning standard. D. Site Surveys are usually conducted several weeks to several months prior to deployment to identify reflector ground control locations, identify and resolve deployment issues (obtain permission or permits), and to verify that the GPS base station receives a high quality signal at the selected primary and backup locations. Kinematic dGPS traces are frequently obtained at this time using one of the base station locations. E. Detailed Acquisition Planning generates a complete acquisition plan including final notched frequency waveforms based upon coordination with the Army Spectrum Office. Flight lines are fully specified and the associated run-time data packets finalized and checked by the Project Manager and the Radar Operators for accuracy and completeness. F. Sortie Packing is the final planning step prior to initiating the Deployment & Acquisition of the raw radar data. In this step the various data take lines are bundled into a flight (sortie) and the corresponding logistical support requirements are determined (e.g., ground control, media, contingency supplies, etc.). The sortie schedule is specified, crews hired, personnel reserved, suppliers hired, and support material inventoried. 2.2 Deployment & Acquisition of Raw Data Production Steps Three major activities take place in this production step. A. Mobilization initiates the acquisition process. If the aircraft requires alternate basing, then it is moved to this base. The aircrew, the Radar operators, and the In-field Acquisition Manager secure local lodging and prepare for the initial sortie.

Data was received in ellipsoid, and two other data sets (NAVD88 and NGVD29) were also created. NOAA Coastal Service Center converted the binary raster grid file to xyz points. The xyz points were projected from UTM zone 11 meters to geographic coordinates using the General Cartographic Transformation Package (GCTP) software. The NGS geoid03 model was used to convert elevations referencing the GRS80 ellipsoid to NAVD88. The coordinates were projected back to UTM zone 11 meters and the xyz points were converted to a binary raster file. In-house routines that used the GDAL open source library converted the floating point raster data sets into Environmental Research System Institute (ESRI) Arc Grids. These grids were then loaded into a single raster data set within ArcSDE using a utility developed with ESRI ArcObjects.