SAM utilizes our own airborne LiDAR scanning system. The hardware consists of a state-of-the-art Trimble Harrier 68i Airborne Laser Scanner that can be deployed from either a helicopter or fixed-wing aircraft. The addition of this technology to our terrestrial, mobile and airborne scanning services gives SAM a full range of in-house LiDAR capabilities and enhances our range of geospatial solutions for clients.
Some of the benefits for our airborne LiDAR project clients include:
- Increased speed and efficiency of data collection
- Higher point cloud data density and accuracy
- Full integration with other mobile and terrestrial LiDAR data
- More options related to data collection altitude, speed and coverage
- Faster turnaround of airborne LiDAR for project applications
LiDAR is an acronym for Light Detection And Ranging, a laser-based system of scanning and capturing high-resolution digital spatial data that can be used for surveying and geospatial applications. The combination of LiDAR scanning technology with an aerial deployment platform allows for extraordinary efficiency and speed for gathering accurate spatial data to support asset management needs for numerous industries, such as power generation and transmission, oil and gas, pipeline, rail and transportation, architecture and engineering, and others.
SAM has utilized aerial LiDAR equipment to provide these services for several years, and has developed considerable expertise with these tools and techniques. With the addition of the state-of-the-art Trimble Harrier 68i airborne LiDAR system to SAM's in-house capabilities, the combination of three different modes of laser data collection gives the firm a full suite of LiDAR services and enhances their ability to provide complete geospatial solutions. The union of fixed-position terrestrial scanning, mobile scanning from a vehicle, and airborne scanning from aircraft offers a powerful set of tools that the firm can bring to bear, depending on project needs.
The Trimble Harrier 68i is the most advanced LiDAR scanning system on the market and has a truly impressive set of specifications, including a very high rate of data capture, extremely dense data capture (or point cloud), a 45-60 degree field-of-view, and an integrated 60 megapixel medium-format digital frame camera. The system is capable of operating at an altitude of up to 5,000 feet and can capture a scan swath width of 83 percent of altitude at 45 degrees. The system offers high accuracy and reliability, minimal calibration requirements, and highest quality data characteristics across the scan. The system also is fully integrated with positioning software and Trimble's TopPIT software for pre- and post-processing of LiDAR data.
One of the benefits of the Trimble scanner over similar systems in operation is the complete integration of scanning components. The laser scanner sensor head, geo-referenced optical frame cameras, navigation control components, data processing and display units, and operational software are all part of one off-the-shelf package, virtually eliminating any compatibility issues found in other aggregated solutions. Another advantage is data compatibility with third-party processing software. Unlike some other systems, the Harrier data is in a non-proprietary format and can more easily be integrated with other geospatial systems. This will be an important for clients that have other legacy data management needs.
A key difference between the Harrier system and other LiDAR systems is its higher data density capability. In addition to enhanced sensor characteristics, the scanner coverage pattern consists of regular parallel lines across the scan path, rather than a saw tooth or sine wave pattern, and provides constant point spacing both along and across the track. The fuller coverage results in higher density data collection and produces a more detailed point-cloud.
In some cases greater efficiencies can be gained by deploying this system from fixed-wing aircraft, rather than helicopters. SAM will also be able to utilize this equipment in that capacity and would work with other airborne providers to provide that service for required projects. The Harrier scanner was designed from the ground up with the flexibility to be used with either fixed-wing or rotary aircraft. The system also has a remote control feature that enables pilot-only operation for minimal project manpower requirements.
The system has a variable scanning rate of 10-200 lines per sec, with each discrete return recorded in a 16-bit high dynamic range value. The system can essentially record an unlimited number of backscattered laser pulse returns from any altitude. At the highest setting this allows the capture of an enormous amount of point-cloud data in a single pass. Using a rotating polygonal mirror, the hardware is extremely durable and only requires one easy calibration annually.
Regarding safety, the Harrier system uses a Class 3R laser to scan a scene and collect data, but the laser is safe for the naked eye beyond 1.5 meters, and safe for aided eyes beyond 10 meters. These distances are well beyond the distance from which the scanner operates in aerial applications. There is no risk to anyone in the flight path.
For onboard data collection the Harrier uses a hard drive-based RAID system with hot-swappable drives. These can easily be changed in-flight, providing a virtually unlimited amount of data storage on any flight operation. The scanning can be controlled either by an operator using an aviation-certified onboard graphical computer with real-time visualization, or by the pilot using a compact graphic terminal that displays all essential information for controlling the scan navigation and data collection.
There is a full suite of software included with the Harrier system, including tools for: flight management, laser control, camera control, positioning control, flight evaluation, flight planning, laser data pre- and post-processing, image processing, POS processing, camera orientation and LiDAR calibration. These packages use industry standard protocols and are tuned to maximize the specific characteristics of the Harrier system. Every aspect of the process, from planning, through data collection, to final data post-processing can be accomplished using the integrated suite of tools included with the system.