The National Oceanic and Atmospheric Administration (NOAA) offers coastal resource managers a variety of data, information and products derived from remote sensing technology. These critical inputs support major resource management programs and facilitate effective decision making.

NOAA’s remote sensing toolbox includes airborne and satellite multispectral systems, interferometric synthetic aperture radar (IfSAR), light detection and ranging (LiDAR) and hyperspectral imaging. As part of its efforts to advance Earth observation science, NOAA recently demonstrated the usefulness of new airborne systems that have delivered high-quality data and energized partnerships to enhance coastal zone management and increase the efficiency of NOAA programs.


IfSAR Delivers Enhanced Elevation Data
One of NOAA’s most ambitious new imagery projects is to acquire IfSAR data collected by Intermap Technologies (www.intermap.com) for areas along the U.S. Gulf Coast. Collected as part of Intermap’s NEXTMap program, the data will be used to produce enhanced elevation data and enhance NOAA’s ability to delineate, model and manage watersheds; map frequently inundated coastal areas; create improved topobathymetric data; and model hurricane storm surge.

Intermap’s acquisition and processing workflow includes the acquisition of radar data streams that are needed to create orthorectified radar image (ORI) data and a digital surface model (DSM). The DSM undergoes further processing to create a bare-earth elevation representation known as a digital terrain model (DTM).

Intermap’s ORI will provide NOAA with gray-scale images that have been corrected to remove geometrical distortions that are a normal part of the imaging process. The product looks similar to a black-and-white aerial photograph, but it’s not made from visible light. Radar pulses the ground with “flashes” of radio waves, which then return from the ground—or whatever they strike, including buildings and trees—to the antennae to give distance and intensity measurements.

The product’s key feature is that it models the surface in a way that accentuates features far more than is possible with aerial photography. The radar looks to the side of the aircraft and casts “shadows” that enable users to visually perceive the elevation information in the image, even if they’re unfamiliar with the underlying technology. The ORI has many applications in value-added products. For example, it can be used to extract cultural features such as road networks and buildings. In addition, an ORI easily lends itself to terrain, land cover and geological analysis. The ORI has a pixel size of 1.25 meters and a horizontal accuracy of 2 meters RMSE.

Intermap’s DSM, a topographic model of Earth’s surface, provides a geometrically correct reference frame over which other data layers can be placed. For example, the DSM can be used to enhance a pilot’s situational awareness, create 3-D fly-throughs, support location-based systems, augment simulated environments and conduct viewshed analyses. The DSM also can be used as a comparatively inexpensive means to increase the accuracy of cartographic products such as topographic line maps, or even road maps. The Intermap DSM delivers elevation observations on a 5-meter grid interval and provides a type I product with .5-meter vertical accuracy, a type II product with 1-meter vertical accuracy and a type III product with a 3-meter vertical accuracy.

 
 

Intermap’s DTM will enable NOAA to manipulate terrain characteristics with surface analysis tools to support a variety of applications, including the development of topographic maps. The DTM also is a valuable component for analyzing various terrain characteristics such as profile, cross-section, line-of-sight, aspect and slope. In addition, the DTM supports flood plain analyses, agricultural applications and intelligent vehicle applications. The Intermap DTM delivers elevation observations on a 5-meter grid interval, and provides a type I product with a vertical accuracy of .7 meters and a type II product with a vertical accuracy of 1 meter.

Seamless Topobathy Data
NOAA and the U.S. Geological Survey (USGS) have co-developed methods to merge elevation and bathymetry data to create a seamless topobathy data layer. Topobathy data sets are being developed and refined to provide a merged elevation and bathymetric surface useful for inundation mapping, habitat modeling and a variety of other applications. New data inputs for elevation and bathymetry will enhance topobathy data creation. In addition, new data fusion approaches will merge enhanced data streams to create “multiresolution” topobathy data that will use the best elevation data available for given areas as input to the seamless surface.
A combined USGS/NOAA study was conducted to create topobathy data for areas near Tampa Bay, Fla. The topobathy creation process involves multiple steps:

• Select terrain data from the best available source, which is typically the USGS National Elevation Dataset (NED), and convert the data to a common vertical reference frame.

• Extract hydrographic survey data from available surveys and soundings. Polygon files should be prepared that bound the areas of specific surveys

• Transform the vertical reference frame of the soundings data to a common vertical reference frame using NOAA’s VDatum Transformation Tool.
 
• Interpolate a bathymetric grid from the transformed soundings.

• Combine the terrestrial and topographic elevation grids to create a seamlessly merged topobathy elevation data model.

 

Data-Specific Projects
NOAA is focused on delivering improved sources of appropriate data for specific tasks, including improving nautical charts, enhancing the characterization of bottom materials and near-shore habitats, improving the classification of coastal land cover and change, and providing detailed maps of critical infrastructure in the coastal zone such as ports and transportation facilities.

Near-Shore Mapping
NOAA and other agencies are considering how best to employ multisensor technologies for data acquisition and fusion. The use of the Scanning Hydrographic Operational Airborne Light Detection and Ranging Survey (SHOALS) system has provided useful data streams for enhanced shallow-water bathymetric and environmental data.

SHOALS surveys have been conducted since 1996 through the Joint Airborne LiDAR Bathymetry Technical Center of Expertise (JALBTCX) at Stennis International Airport in Bay St. Louis, Miss. JALBTCX is a partnership among NOAA, the U.S. Army Corps of Engineers and the Naval Meteorology and Oceanography Command.

The expertise gained during nine years of SHOALS operation has been incorporated into the development of JALBTCX’s next-generation surveying system, the Compact Hydrographic Airborne Rapid Total Survey (CHARTS) system. The CHARTS contract was awarded to Optech Inc. (www.optech.ca), whose researchers work closely with JALBTCX to optimize the CHARTS configuration. Current efforts are under way to deliver the SHOALS 3000 T20
system, which will incorporate a 3,000-Hz hydrographic LiDAR, a 20,000-Hz topographic LiDAR, a frame-based high-resolution multispectral imager, and a CASI 1500 hyperspectral imaging system from ITRES Research (www.itres.com). With the addition of the hyperspectral imaging system, CHARTS will provide enhanced abilities to classify maps that delineate various bottom types such as sand, mud, coral and grasses.

 

Change Analysis
NOAA’s Coastal Change Analysis Program (C-CAP) is a national effort to develop and distribute regional land cover and change analysis data for the coastal zone. Sanborn (www.sanborn.com) and the NOAA Coastal Services Center are working together to use enhanced data streams to provide an improved C-CAP product (see “NOAA’s Coastal Change Analysis Program Monitors Our Changing Coastlines,” page 16) The enhanced program will provide a classification system with improved level of detail for coastal-specific land cover and land use categories. NOAA will use the data to assess new strategies and products, and to help coastal resource managers with water resource management/inventory and environmental protection.
 

Ecosystem Protection
The Northwest Florida Greenway is a partnership of nonprofit, military and government organizations dedicated to conserving critical ecosystems in the Florida Panhandle, one of the most biologically diverse areas in the United States. The partnership includes the Florida Department of Environmental Protection, the Nature Conservancy, the Economic Development Council of Okaloosa County and the U.S. Air Force.

Using an ADS40 digital mapping camera from Leica Geosystems (www.gis.leica-geosystems.com), EarthData (www.earthdata.com) has collected high-resolution remote sensing data for areas in an ecological corridor between Eglin Air Force Base and the Apalachicola National Forest. Working with NOAA, the Northwest Florida Greenway partnership is trying to protect the corridor, which is a critical flight path for the Air Force. Although the data acquisition project primarily focuses on ecological and natural resource management considerations, the data also will be used to extract a high-quality DTM and information about the human infrastructure in areas that are subject to multiple natural hazards, including hurricanes, high winds, storm surge inundation and coastal flooding.
 

Post-Disaster Response
Evaluating changes in the coastal zone environment is a critical responsibility of coastal resource management. Whether considering long-term impacts of sea-level rise or the effects of extreme events such as hurricane, storm surge or tsunami inundation, remotely sensed data provide critical input for depicting baseline conditions from which impacts may be evaluated. The 2004 hurricane season provided an ideal example of how the availability of NOAA image and related spatial data helped disaster management and relief managers identify areas of major damage and to plan appropriate response efforts. The ongoing collection of image and LiDAR elevation data for coastal regions will be critical for monitoring gradual coastline changes, modeling future conditions and responding to emergency situations.
 

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