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Validation of DEM Data Derived from World View 3 Stereo Imagery for Low Elevation Majuro Atoll, Marshall Islands
Citation:
Lunetta, R., D. Davis, AND M. Stege. Validation of DEM Data Derived from World View 3 Stereo Imagery for Low Elevation Majuro Atoll, Marshall Islands. Presented at ASPRS Annual Conference, Tampa, FL, May 04 - 08, 2015.
Impact/Purpose:
An in situ ground survey will be initiated to provide elevation data for use as both ground control points (GCPs) to support photogrammetric model calibration and to provide reference data for subsequent validation of high resolution DEM products. The reference database will consists of surveyed elevation points across Majuro Atoll from the Peace Park located approximately 2.5 km west of Amata Kabua International Airport, extending to the east including the downtown area, and to the north terminating the high tide mark in Rita (Figure 1). To provide a statistically robust reference database, a statistical sampling frame was first developed incorporating a systematic unaligned design to provide relatively equally distributed randomly selected points. Next, random points were generated for each segment including both primary and secondary points. All points were then 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 Excel database of sampling coordinates (n=120), including both primary (n=60) and secondary (n=60) points, was created to support the field survey data collection effort.
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 elevationdata (DTED) which have a 30 m spatial and 5.0 m 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 inundation 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 arean absolute vertical 90% linear error (LE90) of approximately 0.35 m. To validate the adherence to required DEM specifications, a statistically robust reference database was needed.