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USGS and NOAA Host Airborne Lidar Processing System (ALPS) Workshop

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Jamie Bonisteel
Above: Jamie Bonisteel was the primary instructor of the week-long ALPS workshop. [larger version]

The U.S. Geological Survey (USGS) and the National Oceanic and Atmospheric Administration (NOAA) cosponsored a workshop on Airborne Lidar Processing System (ALPS) software, which is used to process lidar (light detection and ranging) data collected from a unique system on a light aircraft. Airborne-lidar data are useful for mapping land and the nearshore seafloor in coastal areas where the water is clear enough to transmit the light emitted by a lidar instrument.

The workshop was hosted by members of the Coastal and Marine Geology Program (CMGP) from the USGS Science Center in St. Petersburg, Florida, in collaboration with NOAA's National Geodetic Survey (NGS) Remote-Sensing Division. Led by Amar Nayegandhi (Jacobs Technology, Inc./USGS), the workshop took place October 27-30, 2009, at the NOAA NGS office in Silver Spring, Maryland. The workshop objective was to provide hands-on training in the ALPS software, and to explore and process lidar data and imagery acquired by the Experimental Advanced Airborne Research Lidar (EAARL) system. The workshop also gave participants an opportunity to discuss collaborations on the acquisition and application of lidar data and development of the ALPS software. The workshop included representatives from Federal agencies and academia, including the National Park Service (NPS), the U.S. Bureau of Reclamation, the U.S. Forest Service, NOAA, and the University of Idaho.

The EAARL is an airborne lidar system that provides unique capabilities to survey coral reefs, nearshore benthic habitats, coastal vegetation, and sandy beaches. Operating in the blue-green portion of the electromagnetic spectrum, the EAARL is specifically designed to measure shallow submerged topography and adjacent coastal land elevations seamlessly in a single scan of transmitted laser pulses.

diagram showing how lidar works
Above: How lidar works. Light reflected from various surfaces provides mapping information about features on land and beneath shallow (light-transmitting) water. Graphs show generalized patterns of data returned from vegetated land (left) and submerged topography (right). I=intensity of returned light; t=time. [larger version]

The USGS ALPS software has been developed in an open-source programming environment on a Linux platform. ALPS supports the exploration and processing of lidar data acquired by the EAARL system in an interactive mode or batch mode. The workshop provided hands-on training for attendees to interact with modules developed for lidar-raster and waveform investigation and digital-camera-image playback. The class covered processing workflow—the steps involved in converting raw lidar data to digital-elevation models (DEMs) that represent submerged, bare-earth (elevation of ground surface beneath vegetation), or canopy (elevation of top of vegetation) topography—including automated and semi-automated tools to filter and manually edit data. The training workshop also provided an opportunity for users to better understand the EAARL lidar waveforms and to explore the use of these waveforms in various scientific, inventory, and monitoring activities.

The workshop began with several presentations explaining EAARL, ALPS, and how the CMGP is collaborating with various Federal, State, and local agencies to obtain high-resolution topographic and bathymetric data for scientific studies and resource management. John Brock (USGS, Reston, Virginia) presented the history and importance of developing this lidar capability in the CMGP. The principles and capabilities of the EAARL system were summarized by Wayne Wright (USGS, St. Petersburg). Nayegandhi then provided an overview of ALPS.

Subaerial (land) and submerged (seafloor) topography on and around St. John, U.S. Virgin Islands, created from lidar data collected by EAARL in 2003.
Above: Subaerial (land) and submerged (seafloor) topography on and around St. John, U.S. Virgin Islands, created from lidar data collected by EAARL in 2003. The subaerial topography is “first surface” topography, produced by using data from laser pulses that bounced off the first surface encountered, typically the tops of trees or buildings. The ability of the lidar system’s laser light to penetrate shallow, nearshore water enabled the creation of this seamless topobathymetric mosaic. WGS stands for “World Geodetic System,” a standard reference frame for mapping and other uses. WGS 84 was produced in 1984 and last revised in 2004. Color-coded elevations are in meters (m). [larger version]

The workshop continued with hands-on, guided instruction on how to use ALPS, interspersed with presentations on related topics. Jamie Bonisteel (Jacobs Technology, Inc./USGS) was the primary instructor. Chris Parrish (NOAA/NGS) presented NOAA NGS Remote-Sensing Division use of EAARL data in shoreline mapping, and Nayegandhi explained the mapping of vegetation structure using waveform lidar. Jim McKean (U.S. Forest Service) presented an overview of the application of EAARL submerged and floodplain topography data in riverine environments. Richard Mitchell (Jacobs Technology, Inc./USGS) and Wright introduced the new ALPS Multi-Processing System (AMPS), which is capable of reducing the processing time by several orders of magnitude, thereby enabling a quick review of data in the field. David Nagle (Jacobs Technology, Inc./USGS) demonstrated the use of ALPS in conjunction with commercial software to georeference and mosaic color-infrared (CIR) photography that is collected by the EAARL system simultaneously with lidar data. Xan Yates and Emily Klipp (Jacobs Technology, Inc./USGS) presented an overview of the process of publishing lidar data as USGS Data Series DVD products. The published data products ensure that high-resolution digital-elevation data are available to the research community and the general public in a format that is fully documented and usable in standard Geographic Information System (GIS) software. The workshop ended with a demonstration of Global Mapper—software for viewing and manipulating spatial datasets—presented by Bonisteel, who showed examples of how to plot, review, and interact with DEMs and CIR photography processed in ALPS.

Related Sound Waves Stories
Remote-Sensing Technologies Provide Unique Maps and Datasets to Support Coastal Scientists, Managers, and Decision Makers
October 2009
New England Lidar Workshop
August 2009
Airborne Lidar Processing System (ALPS) Workshop
June 2008

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Measuring Tidal Flows in the Cape Cod Canal

Research Peace River Vulnerable to Running Dry

New Discoveries Could Improve Climate Projections

Arctic Could Face Warmer and Ice-Free Conditions

Meetings CCAA Miami Conference on the Caribbean and Central America

Tampa Bay Area Scientific Information Symposium

Antarctic Treaty Summit

SACNAS National Conference

Airborne Lidar Processing System (ALPS) Workshop

Awards Awards for USGS Publication on the Coral Reef of South Moloka‘i, Hawai‘i

Staff New USGS Director Visits Centers in California

Gaye Farris Retires from the USGS National Wetlands Research Center

Publications Jan. / Feb. 2010 Publications List

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