A deeper look at bathymetric LiDAR sensors and UAVs
Bathymetric LiDAR is an airborne acquisition technology or technique that uses green wavelength to pierce the water column in order to measure the seafloor. That is why it is the most effective as well as cost-efficient technology to capture geospatial data of the coastline and seafloor simultaneously. Its ability to successfully provide a continuous, detailed 3D elevation model of the coastline, over areas stretching more than 100km, has made it the ‘gold standard’ for efficient and fast creation of hydrographic data and near-shore benthic habitat modeling. Keep reading to learn more about this approach and its various applications.
Characteristics of bathymetric LiDAR sensors
In comparison to topographic LiDAR sensors, bathymetric sensors arguably tend to have more individual features and differences. An interesting trait is that all modern bathymetric LiDAR sensors can measure topography in addition to bathymetry. This particular technology can be simplified into four major components: the GPS receiver, the IMU (inertial measurement unit), the laser scanner, and the sensor. They can also be divided between the shallow-water and deep-water systems. In this case, the shallow-water (<10m) systems can typically only measure water depths within the visible water column and smaller laser footprint diameter.
Laser energy in bathymetric LiDAR systems
A paramount consideration when utilizing bathymetric Lidar systems is laser energy per pulse, as it is the strongest influence on depth penetration (besides factors like receiver telescope area and field of view). Although high laser power and pulse duration tend to result in deeper water column puncturing, the measurement frequency is lower which results in a lower point density. Nevertheless, full insonification of the seabed is still possible.
Advancements in Bathymetric LiDAR sensors
Recent advances in this type of LiDAR sensors have been heading in different directions. Some include more integrated systems with additional sensors, greater point density, numerous sensors in the aircraft, reflectance calibration between flight lines, enhancements for freshwater capture, and enhanced classification of point clouds. Additionally, it is still early for the use of bathymetric LiDAR in small unmanned aerial vehicles (UAVs), although this is presumably to change in the next ten years.
LiDAR bathymetry can provide accurate, thorough, and cost-effective results that allow the analysis of microtopography and hydrological features in remote locations around the world where traditional survey methods cannot be feasible. It is always important to consider the environmental factors and the individual characteristics of a system when selecting and employing this technology. However, in most cases, success is often determined by the knowledge and experience of the operator. For more information on this topic, contact us today.