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OPTEN’s airborne laser survey equipment comprises a customized laser terrain mapper (LiDAR), a high-resolution digital photo camera, a video camera, and various controllers.
We consider high mobility of the laser survey equipment as one of the main its advantages. It gives us an opportunity of operating our system worldwide; besides using local aircraft companies adds to efficiency and safety.
The way LiDAR operates has much in common with a typical radar system. LiDAR pulses a laser beam onto the periodically oscillating mirror and projects it downward. The laser beam hits an object and reflects back to the mirror. As a result, the scanner receives reflections of all the objects within the survey swath. High-speed counters measure the time interval between the pulse leaving the airborne platform and its return to the LiDAR sensor. LiDAR time-interval measurements are converted to distances and correlated to the information recorded by GPS receiver, Inertial Measurement Unit (IMU), and ground-based GPS stations.
3-dimensional GPS solution (X, Y, Z) is used to position the laser scanner at each second or half second, while the IMU data is used to determine the system’s orientation. The GPS solution is computed from differential kinematic processing, using data collected simultaneously at the aircraft and at base stations at or near the project site.
Our system is capable of discriminating among multiple returns from each pulse measuring not only the position and geometry of the surface below the aircraft, but also the terrain under the vegetation cover. Such a method of registering first, intermediate and last pulses defines one of the advantages of the technology used by OPTEN - identify and measure the position of on-ground objects, map the land surface under the vegetation layer and obtain spatial model of vegetation. We use this important feature of the system together with proprietary data processing algorithms to create digital terrain model not affected by the vegetation.
Prior to data acquisition, we perform a calibration flight to ensure the system meets or exceeds its specifications. Following the acquisition, preliminary data processing is conducted in the field to ensure its completeness and integrity. This step is a quality control process to ensure that coverage is complete and that the equipment was functioning well. In case the gap or unacceptable data quality is detected, the crew isolates the problem areas and re-flies the affected sections before demobilizing.
The GPS and inertial data are processed together to achieve the best positional result. Once the position and attitude of the aircraft are known at each period (1 or 0.5 -second intervals), this data is integrated with the laser reflections to provide a position for each point on the ground. The data is processed using the proprietary laser-processing software suite to produce an ASCII file of (x,y,z) coordinates. Quality control of the collected data is an ongoing process throughout the survey.
The survey characteristics such as the flying height, survey swath, density of the points depend on the final results required by the Customer. Each time we adjust the survey parameters to the thoroughly worked out specification and agreed pricing.
Towards the final product output various operations are performed over the collected survey data. Among them initial laser points computation, laser data classification to ground and non-ground points, objects recognition, digital photographs orthorectification, thematic objects processing and many others in line with the Client’s specification. All operations are performed in accordance with detailed Quality Assurance plan, which becomes part of the contract. Please, contact us to get more information about our technological chain.
It is the final product of our services that makes us different from other LiDAR companies. We dedicate our efforts to production and quality control of the product that exactly addresses your needs. We do not produce "laser points", but the solutions that help maintaining efficiency of your business.