ALS is a direct remote sensing system which permits accurate elevation measurements for a precise and easy terrain modelling. Laser sensors are able to measure a huge quantity of points in a short time. The characteristics of the point cloud will depend on our client requirements and the terrain complexity.
Basically, an airborne laser system consists on a GPS receptor and an inertial navigation system, that provide the position, trajectory and aircraft orientation, the laser emitter and the mirror that are responsible of the point cloud acquisition. Points are represented with XYZ coordinate.
STEREOCARTO currently owns airborne LEICA ALS50-II LiDAR sensors.
• Height of flight: 200 m – 6.000 m.
• Frequency: up to 150.000 Hz (150.000 pulses/sec.)
• FOV: 10º - 75º
• Accuracy: 11 cm (altimetry)
• Raster resolution: 0,3 m a 5 m
• Point density: up to 12 points/m2
Orthophotography and LiDAR
The quality and the precision of orthophotografy depend on the Digital Terrain Model quality. LEICA ALS50-II sensors offer a wide range of height flights and FOV's for the more suitable performances, reaching an accuracy of 15cm in altimetry and 50cm in planimetry, with a point density of about 4,3 point/m2. Due to their characteristics, these systems reduce the orthophoto generation process time and hence the costs of the process.