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Lidar Tips

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The HELIX System is a helicopter mounted LiDAR system that is capable of providing flexible data acquisition techniques to meet most terrain conditions. The LiDAR ranging component of the system is comprised of a custom designed near INFRARED laser scanner (1064 nm wavelength) and a nadir laser profiler (904 nm). The scanner provides the wider area data collection and the profiler provides an extremely high-density profile that has a high vegetation penetration capacity. (Since the profiler laser beam is generally parallel with most vegetation features, higher penetration ratios are experienced, resulting in implementation of enhanced bare-earth QC techniques.) HELIX integrates laser technology with GPS, IMU and imagery sensors for a state of the art data collection system.


The scanning system operates in a First or Last return mode, includes return intensity and has a range of operation from 100m to 1000 m above ground level (AGL). The Helix scanner produces a 60º swath, +/- 30º from aircraft nadir. The beam divergence of the exiting laser pulse is 0.5 milli-radians and results in a beam footprint diameter of 1/2000th of the flying height.


The nadir profiler laser is fixed mounted to point directly under the helicopter. It's pulse rate is at a rate sufficient to provide a continuous laser coverage throughout the entire flight. The profiler operates in a last return mode only.


Since the system is helicopter-based, the flight parameters can be modified to provide the best solution to address any terrain challenges. The helicopter ground speed in normal flatter terrain is 65 to 85 kts. In steeper terrain, the acquisition speed will be reduced to support safe operation contouring the slope. To address point density, flight line overlap areas can be adjusted in addition to the data collection speed to meet the project specifications.


Advantages of the HELIX Helicopter LiDAR system:


HELIX can be flown to follow terrain features such as; transmission line and pipeline corridors, highways, railway corridors, rivers, canals, shorelines, canyons, and other non-linear features, and is not dependent on parallel flight lines for area coverage.

HELIX can be flown from 100 m to 1000 m above ground.

By flying lower and slower the HELIX system delivers a very dense grid of laser postings on the ground, considerable more dense than a fixed wing LiDAR system.

The LSI helicopter does not need to operate out of an airport and can be based very close to the project area thereby keeping non-productive ferrying times to a bare minimum. This is very advantageous for very remote project areas. Helicopter fuel is brought into the project area via vehicle or by helicopter to maximum survey production during the day.

During periods of poor weather and low ceilings when a fixed wing LiDAR system would be grounded, the LSI HELIX helicopter system would still be working. More production equates to a faster project completion.

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Jeepers - I did a test flight of a prototype of a laser system like that using an inertial nav system in the early - mid 80's - 2 days 5 feet above the trees - fun.

Got great results - tree height, underbrush and terrain profile along with XYZ position. We had a vertically mounted video camera also.

As with all inertial survey had to land every 3-4 minutes to stabilize the inertial platform ( Ferranti system in this case - same platform as the Harrier used) ( the other system we used was Litton from the USofA)

The 3-4 minute rule kept another helicopter busy with 3 cutting crews making pads pads for us.

It was for a survey company working for Hydro Quebec.

Never new anything came of it. Perhaps' however, this is a system developed elsewhere - who knows. Mind you that baggage door for the Laser looks awfully familiar.

The GPS would sure make it a lot more efficient system. Neat

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