Collaborative Research: Facility Support for Operation of the National Center for Airborne Laser Mapping (NCALM)

University Of Houston, Houston TX

Investigators

Abstract

This award continues the support of the National Center for Airborne Laser Mapping (NCALM), which is a collaboration between the operational facility at the University of Houston and the data-processing center at the University of California Berkeley. Also known as airborne Light Detection and Ranging (LiDAR), airborne laser mapping allows for the measurement of surface topographic features with very high accuracies and spatial resolution. The data collected are used to construct very detailed digital elevation models (DEM) that offer an unprecedented high-resolution representation of topographic features and illuminate the processes that shape them. Examples include fault scarps, hill slopes, river channels, barrier beaches and sand dunes, mountain and continental glaciers, volcanic edifices and the structure of the forest canopy. This facility gives researchers access to the sophisticated technology and operational support needed to gather the data and the expertise required to convert that data into visual products. DEMs developed from LiDAR have a wide range of applications in civil engineering and hazards assessments to see how much the land surface has moved over a specific time interval, and in archaeological investigations of how past civilizations have modified landscapes, especially in tropical regions where such structures are hidden from view by dense forest cover. NCALM is dedicated to meeting three goals: 1) providing research-quality LiDAR data to the scientific community, 2) advancing the state of the art in airborne laser mapping, and 3) training and educating graduate students to meet the rapidly growing needs of academia, government, and the private sector. This continuing award will allow NCALM to augment collection platforms with a flexible and portable helicopter-based system, expand the use of multi-wavelength LiDAR and coincident hyperspectral imagery, work with other NSF centers to explore unmanned aircraft, focus on open-source software tools and methodology for change detection between temporally spaced LiDAR collections, and provide workshops and community engagement to disseminate the LiDAR knowledge that NCALM has acquired and developed. Airborne laser systems fire laser pulses at high frequency from an aircraft whose position and orientation are monitored via on-board and ground Global Positioning System (GPS) control and an aircraft Inertial Measurement Unit (IMU). The instrumentation measures the round-trip travel time for individual pulses to reflect from encountered surfaces and return to a detector. Raw travel-time data are combined with position information to generate georeferenced coordinates of each laser return from the surface or "point clouds." The system's high-frequency laser postings allow for penetration of dense vegetative canopies and, with developed post-processing routines, can yield maps of both the upper surface of the vegetative canopy and the bare Earth surface that is obstructed from a bird's-eye view. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.