TWH operates with the latest market leading Teledyne ALS Sensors. Our aircraft has operated with Reigl LiDAR sensors and Leica Sensors. We are happy to fit your sensors if you just require a survey aircraft.
Airborne Laser Scanning (ALS) is a technology which provides high density digital elevation models and digital surface models. The ALS system emits discrete laser beams, and records the time taken for the laser to return to the aircraft. It consists of a high frequency laser, Inertial Measuring Unit (IMU), and Global Positioning System (GPS).
Background Basic Principle of ALS
Airborne Laser Scanning (ALS) became operational around the early to mid-1990’s as wide area terrain mapping tool. It was adopted soon after in the USA, where the term LiDAR (Light Detection and Ranging) was adopted as the term for the technology.
The ALS system emits discrete laser beams, and records the time taken for the laser to return to the aircraft. It consists of a high frequency laser, Inertial Measuring Unit (IMU), and Global Positioning System (GPS).
The point clouds represent the simplest form of ALS data: the discrete 3D coordinates of whatever the laser beam strikes. “Classified” point clouds refine the data one step, by using algorithms to decide what the laser strike has hit: ground, vegetation, canopy, transmission wires, building etc. The density of the ALS point cloud collected depend on the application of use.
The “Classified ground points” provide the rawest definition of the terrain. They are typically loaded into GIS and Engineering software for 3D modelling, contour generation, slope analysis, flood modelling, erosion mapping or other general ground analyses.
The “Classified non-ground points” give an indication of the density of the overlying vegetation. The “Classified canopy strikes” are a sub-set of the non-ground strikes and define the top of the vegetation surface. This is used for calculating tree heights, fuel loads, carbon counting etc.
The laser is reflected from electricity towers and conductors, as well as from the vegetation beneath the conductors. This data provides definition of the “danger points” between conductor and vegetation, at the time of the ALS survey. Modelling software can predict the extra sag in the conductor catenary if the load through the conductor is increased. This is valuable information when optimising the load along an existing line.
ALS strikes on buildings can be “classified” and building heights can be determined. These strikes can be used to help with design of noise reduction barriers, city planning, shadow analysis, airflow modelling, lie-of-site calculations, and many other applications.
TWH | TWLdata 