A simulator for airborne laser swath mapping via photon counting

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

et al. 2010

Recent technological advances in the performance of small micro-lasers and multi-channel multi-event photo-detectors have enabled the development of experimental airborne lidar (light detection and ranging) systems based on a low-SNR (LSNR) paradigm. Due to dense point spacing (tens of points per square meter) and sub-decimeter range resolution, LSNR lidar can likely enable detection of meter-scale targets that would go unnoticed by traditional lidar technology. Small vehicle obstructions and other similar targets in the beach and littoral zones are of particular interest, because of LSNR lidar's applicability to the near-shore environment and the general desire to improve detection of antivehicle and antipersonnel obstacles in the coastal zone.A target detection procedure is presented that exploits the detailed information available from LSNR lidar data while diminishing the effect of spurious noise events. Consideration is given to detection in both topographic and bathymetric scenarios. Data sets for target detection analysis are supplied by a numerical sensor simulator developed at the University of Florida. Target detection performance is evaluated as a function of environmental characteristics, such as water clarity and depth, and system parameters, specifically transmitted pulse energy and laser pulse repetition frequency. Analysis of results with regards to consideration for future system design is discussed.

Section: Target Detection Proceduresmentioning

confidence: 99%

Predicting Small Target Detection Performance of Low-SNR Airborne Lidar

Cossio

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

et al. 2010

“…The laser operates with a beam divergence of 0.25 milliradians, a transmitted pulse duration (t) of 10 ns (3 m of path length), and a near-infrared wavelength (l) of 1064 nm (Carter et al 2001). The system records the ranges of the first and last return pulses using a constant fraction discriminator at the output of an avalanche photodiode detector to detect the full width at half maximum (FWHM) points on the returned laser waveform (Slatton et al 2005). As with all discrete-return ALSM systems, the pulse length imposes a lower limit on the vertical resolution between return pulses.…”

Section: Collection Of Alsm Datamentioning

confidence: 99%

Prediction of forest canopy light interception using three‐dimensional airborne LiDAR data

Lee

International Journal of Remote Sensing

Roth

et al. 2008

Self Cite

The amount of light intercepted by forest canopies plays a crucial role in forest primary production. However, the photosynthetically active part of this intercepted solar radiation (IPAR) is difficult to measure using traditional ground-based techniques. In situ measurement of IPAR requires labour-intensive field work, often resulting in limited datasets, especially when collected over extensive areas. Remote sensing methods have been applied to the estimation of light interception in forests, but until recently have been restricted to twodimensional image data. These approaches do not directly account for the threedimensional structure of forested canopies, and therefore predicting IPAR for arbitrary sun positions is problematic. We utilized a 3D point cloud dataset acquired via an airborne laser ranging (LiDAR) system to predict in situ measured IPAR. This was achieved by defining a field-of-view (scope) function between observer points just above the forest floor and the sun, which relate IPAR to the LiDAR data over southern pine experimental plots containing a wide range of standing biomass. A conical scope function with an angular divergence from the centreline of ¡7u provided the best agreement with the in situ measurements. This scope function yielded remarkably consistent IPAR estimates for different pine species and growing conditions. IPAR for loblolly stands, which have diffuse canopy architecture, was slightly underestimated.

“…Researchers at MIT Lincoln Labs [ Marino et al , 2005], NASA Goddard [ Degnan , 2002], and the University of Florida [ Slatton et al , 2005] are pursuing the development of ALSM instruments based on a new paradigm that employs much lower pulse energies. The UF design was inspired by a NASA prototype for a satellite‐based LIDAR instrument [ Degnan , 2002], and addresses what we see as the three primary limitations of current ALSM systems: pulse duration, wavelength, and spatial sampling.…”

Section: Emerging Alsm Technologymentioning

confidence: 99%

“…CATS uses a frequency doubled Nd:YAG micro‐laser [ Slatton et al , 2005]. The 4.5 μ Joule pulse energy is roughly an order of magnitude less than that of most commercial ALSM lasers.…”

Section: Emerging Alsm Technologymentioning

confidence: 99%

Airborne Laser Swath Mapping: Achieving the resolution and accuracy required for geosurficial research

Geophysical Research Letters

Carter

Shrestha

et al. 2007

122

Modern Airborne Laser Swath Mapping (ALSM) instrumentation, with laser pulse rates in excess of 100,000 Hz, has made it possible to map topography over hundreds of square kilometers per day, with sufficient resolution to answer long standing questions and test new theories pertaining to land surface processes. But sensor technology is changing rapidly, and its operation is sufficiently complex that data collection and processing methods must continue to evolve to take advantage of sensor advances. In 2003, the National Science Foundation established the National Center for Airborne Laser Mapping (NCALM) to collect and process ALSM data. As a result, more research‐quality ALSM observations have become available to the earth science community. But as the amount of available ALSM data rapidly increases, it becomes imperative to identify and describe the parameters that control data quality, so that data sets may be evaluated as to whether they are adequate for particular applications.