ALS

Airborne Laser Survey

4,142 hectare of the high-accurate LIDAR data collected and processed as a result of Airborne laser surveying of the to generate topographic map, DTM and orthophoto for development and reconstruction of the National Park and resort infrastructure. Project turn around 2 months

Products provided by ALS includes:

Digital Terrain Models (DTM)

Digital Surface Models (DSM)

Ortho-Photos and mosaics

Topographic maps

Other LIDAR data

A pulsed semiconductor laser is typically used as an emitter of rays with frequencies in the near infrared. With each scan, measurements are taken of the slant range to the point of reflection and of the beam angle in the locator coordinate system. Depending on the type of a laser locator, more than one (up to fife) reflections can be registered for each scan line. This capability renders laser images more informative as responses from several objects of the scene can be received simultaneously with each single scan. First reflections will be received from foliage, wires and towers of power transmission lines, edges of buildings while last reflections will usually come from the ground or other hard surfaces like roofs. The path of the aircraft is registered by an airborne GPS (GNSS) receiver and its orientation by INS data. Position data obtained together with measured slant distances and scan angles provide absolutely accurate 3D positions of each reflected laser beam. Putting it simply, a modern laser scanner can be defined as a scanning laser range-finder backed by navigation system. All major components of a laser scanner such as range-finder, GPS, INS (inertial navigation system) are well known and have been used extensively for many years. The combined strength of an airborne laser scanner and a digital camera installed on a single airborne platform offer a new instrument - the Airborne Laser Scanning. (Courtesy of Geokosmos).

Laser scanning works day or night- does not require sunlight, is totally digital to allow fast processing for practically overnight turnaround of fully 3D XYZ coordinated points, is easy to set-up and install on airborne platforms. Laser scanning data collected from airborne platforms generate millions of 3D-points which are the base for detailed spatial models.

Advantages of Aerial Laser Survey (ALS):

In surveying terrain features and ground objects or taking geometric measurements, an absolute accuracy of 10-20 cm can be achieved thus making it possible to use Airborne Laser Survey data to create or update topographic maps and plans at almost any scale down to 1:1000 – 1:2000.
The efficiency of Airborne Laser Survey is exceptionally high. There are proven records of 500-600 km of linear facilities surveyed in one survey day.
Airborne laser survey does not require ground geodetic surveying to provide plane and vertical control of aerial survey data.
Airborne laser survey allows all elements of the scene to be measured directly. At the same time, laser measurements create a 3D image of an object - a cloud of laser points reflected off the surface of the object.
Data can be effectively analyzed using software to build vector models, which is essential for the implementation of modern design and mapping approaches.
In contrast to classical methods, Airborne laser survey is not generally affected by seasonal restrictions caused by foliage. In most cases laser beams can be used to locate objects under the tree canopy.
The laser survey method can be applied without any restrictions to survey terrain surfaces having no or few distinguishable features such as quarries, tundra, sand beaches, snow-covered or water areas. It is common knowledge that stereophotogram-metric measurements of such surfaces cannot be made as it is impossible to correlate points in stereographs.
Cost-effective total survey management solution where conventional systems are limited.