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Validation Of DEM Data Dvied From World View 3 Stero Imagery For Low Elevation Majuro Atoll, Marchall Islands
Citation:
Lunetta, R., D. Davis, AND M. Stege. Validation Of DEM Data Dvied From World View 3 Stero Imagery For Low Elevation Majuro Atoll, Marchall Islands. Presented at ASPRS Annual Conference, Tampa, FL, May 04 - 08, 2015.
Impact/Purpose:
This will be a poster presentation
Description:
The availability of surface elevation data for the Marshall Islands has been identified as a "massive" data gap for conducting vulnerability assessments and the subsequent development of climate change adaption strategies. Specifically, digital elevation model (DEM) data are needed to support modeling efforts to assess vulnerabilities to extreme tide events, storm surge wave events, and unusual swell conditions. The only data currently available for the entire Majuro Atoll are the National Geospatial Intelligence Agency (NGA) digital terrain elevation data (DTED) which have a 90m spatial and 16m vertical resolution. Due to the low elevation profile (< 3.0 m), small land mass (< 10 km2), and narrow geographic profile (0.5 km wide) of Majuro Atoll, high spatial (1.0 m) and vertical (< 0.5 m) resolution DEMs are required to support initial vulnerability modeling efforts. The cost effective application of new higher resolution World View 3 (WV3) stereo satellite imagery with a nominal spatial resolution of 0.31 m will be used to create high resolution elevation data. DEM specification objectives are an absolute vertical 90% linear error (LE90) of approximately 0.35 m. A ground survey will be conducted to provide elevation data for use as ground control points (GCPs) to support photogrammetric model calibration and to provide reference data for subsequent validation of the DEM product. A reference data statistical sampling frame was developed incorporating a systematic unaligned design to provide relatively equally distributed randomly selected points. Using WV2 imagery collected on March 4, 2014 (during a high tide event) the normal high water boundary was first established, total upland area was calculated, and 60 equal area linear segments were delineated for the eastern half of Majuro Atoll. Next, random points were generated for each segment including both primary and secondary sampling points. All points were plotted over the WV2 imagery and assessed for potential collectability. Problematic points (i.e., landing on structures, dense vegetation, etc.) were eliminated and a final list of coordinates (n=120) including both primary (n=60) and secondary (n=60) was established to support the filed survey data collection effort.