For performance of aerial laser scanning the “Meridian+” Enterprise possesses a modern aerial laser scanning system ALS 50-II (Leica Geosystems, Switzerland), which provides high-density point cloud with high spatial coordinates accuracy (10 – 13 cm). Capability of lidar survey at low (200 m) and high (6000 m) altitudes provides for a wide range of the equipment’s application.

Main technical characteristics of the ALS-50-II aerial laser scanner

Pulse rate	20 kHz (at 6.0 km height) 30 kHz (at 4.7 km height) 60 kHz (at 2.0 km height) 100 kHz (at 1.0 km height) 150 kHz (at 0.5 km height)
Scanning frequency	Up to 90 Hz at a 10° scanning angle
Scanning angle	10° - 75°
Minimum and maximum slant range, minimum height for scanning angle 45 °, m	200 – 6000, 5500
Planned coordinates determination accuracy (average deviation, m)	After post-processing, depending on slant range for scanning angle 45°: 0.12 at Н=500 m 0.14 at Н=1000 m 0.18 at Н=1500 m 0.22 at Н=2000 m 0.30 at Н=3000 m 0.60 at Н=6000 m
Points height determination accuracy (average deviation, m)	After post-processing, depending on slant range for scanning angle 45°: 0.11 at Н=500 m 0.12 at Н=1000 m 0.13 at Н=1500 m 0.14 at Н=2000 m 0.17 at Н=3000 m 0.25 at Н=6000 m
Registered reflections number	4 (first, second, third and the last)

Advantages of the ALS-50-II aerial laser scanner:

Wide range of possible scanning angles;
High-altitude survey capability;
High planned accuracy of determination of laser reflection points’ allocation;
High accuracy of determination of laser reflection points allocation at high survey altitudes;
MPiA regime (Multiple Pulses in Air), which provides high-density of laser reflection points even at relatively high survey altitudes.

Example of points density for set survey parameters:

Scanning angles - 25°
Flight altitude - 1560 m
Aircraft speed – 300 km per hour
Average points density – 2.5 points per m²