Want to learn all about cutting-edge LiDAR technologies and best practices for mapping shorelines and shallow water? The International LiDAR Mapping Forum (ILMF), taking place Feb. 17-19 in Denver, Colo., is offering a first-hand look at the latest techniques and technologies and the expanding roster of applications for 3D bathymetric models and maps of shorelines and shallow water.
The three-day Technical Conference will feature world-leading experts in bathymetric LiDAR who will detail the latest technology advances and recent projects, highlighting actual experiences and lessons learned.
Bathymetry involves mapping coastal zones and shallow water by using aircraft equipped with a LiDAR system to measure and chart the depths and shapes of submerged terrain along shorelines and other shallow water areas to generate a 3D elevation model of the underwater topography.
The applications for coastal and shallow water bathymetric LiDAR data are incredibly diverse and growing rapidly in number. From flood hazard assessments and natural resource exploration to undersea cable and pipeline route planning, bathymetric maps are also an increasingly important tool for scientists studying future impacts of climate change on the environment.
Kicking off ILMF’s Coastal Zone & Bathymetric LiDAR track on Monday, Amar Nayegandhi, manager of elevation technologies at AEC firm Dewberry, will present “Determining reliable water surface returns in airborne LiDAR topobathymetry.” He will discuss results of a study using two LiDAR systems to simultaneously collect data under various conditions of water surface roughness, which play a big role in obtaining reliable water surface returns.
Amelia Vincent, Project Water Resources Engineer, URS Corporation, will deliver the next session in the track entitled “LiDAR Processing vs. H&H Modeling: The long term impact of short term savings” which will focus on the disadvantages to partially processing LiDAR from a hydraulics and hydrology (H&H) modeling perspective. Additionally, it will investigate why reducing the processing area to save money can mean long-term headaches and unexpected costs.
Later that afternoon, Swante Welander, marketing manager for Airborne Hydrography Airborne Hydrography AB, will discuss the first survey results from the new-generation Hawkeye III, a combined airborne multi-sensor LiDAR system with two bathymetric channels, and one topographic channel.
Following Welander on Wednesday is Optech Manager Joong-Young Park, who will demonstrate his company’s airborne LiDAR system. The Optech CZMIL emits short-pulse widths for increased vertical resolution, which helps separate the seafloor from the sea surface in turbid and dynamic water to create high-resolution 3D data and imagery at one-meter spatial resolution. Park’s presentation is titled, “Enhanced Depth Measurement from Airborne Bathymetric LiDAR Systems in Shallow and Turbid Water.”
In the Coastal Zone Mapping, Bathymetry track, a presentation on Tuesday will explore results of a recent study that used a RIEGL VQ-820-G airborne laser scanner to collect topo-bathymetric LiDAR data for a major coastal restoration project on Terra Ceia Island, on the southern shore of Tampa Bay, Fla. Alvan Karlin, senior GIS scientist at the state’s Southwest Florida Water Management Division, will discuss the advantages of topo-bathymetric LiDAR in densely vegetated areas and compare the study’s results to those from a 2007 study, when the area was last mapped.
Later that afternoon, Peter Shih, professor at National Chiao Tung University in Taiwan, will also present on the effectiveness of using a green-wavelength LiDAR system for bathymetric mapping. His presentation, “Dongsha Atoll Substrate Classification with Reflectivity Derived from Bathymetric LiDAR,” compares the LiDAR system to green-wavelength satellite imagery.
One of the biggest challenges in bathymetric LiDAR is conducting high-resolution topographic mapping in a single pass to generate reliable water surface elevations at the overlap of land and very shallow water, where light from the LiDAR system refracts and changes in speed as it enters the water column. Spatial resolution captured by airborne LiDAR systems also can vary based on altitude, scanning rates, and water clarity, depth and reflectivity.
However, recent advances in bathymetric LiDAR technologies have ushered in a new suite of green-wavelength airborne LiDAR systems for bathymetry that provide seamless topography across the land-water interface at spatial resolution as high as six points per square meter. Green-wavelength light emitted from LiDAR systems provide maximum penetration in shallow water, although the light intensity decays as it travels the depth of the water column.
ILMF 2014 will cover the latest advances in this technology. Other presentations at the ILMF 2014 highlight mobile mapping systems used to support transport, urban modelling, utility asset management, 3D visualization and GIS applications.
Press Release, January 14, 2014; Image: Spar Point Group