Terrestrial laser scanning: Comparison of time-of-flight and phase based measuring systems
Abstract
Terrestrial laser scanning is being used at an increasing rate for a continuously expanding range of tasks. Presently, laser scanners commonly employ two different range measurement principals; either time-of-flight or phase based measurement. Each system has advantages and disadvantages relating to its maximum range, speed at which it captures data, and achievable accuracy. Therefore, it is becoming more common for a user of this technology to have both systems at their disposal to be used in the appropriate situation. Knowledge of the differences in behavior between scanner types, as well as their individual capabilities and limitations is critical for effective project planning and providing quality statements about the data collected. As this technology continues to grow and new markets and uses are discovered, the demand for this precise knowledge and understanding will increase. Laser scanners in general react differently in different situations. The range and angle of incidence to the scanned object as well as the surface properties of the object are all factors that influence scanning results. Testing has been done in each of these categories with older generation time-of-flight scanners, but less work has been done with current time-of-flight scanners or phase based systems. An experiment was designed to test how both types of scanners (time-of-flight and phase based) react to different surface properties at varying ranges and angles of incidence. The test was conducted by scanning a target containing samples of twenty materials ranging from various colors of paint to common construction materials at typical ranges and angles with each scanner types. The analysis and results provides insight into how each scanner reacts to certain situations, the difference in results between the scanner types, and therefore provides valuable information into the most appropriate situation for each scanner type to be used in as well as how the quality of the data differs in each scenario. The results can be used for project planning to help avoid undesirable results due to certain combinations of surface material, range, angle of incidence or scanner type.
Degree
M.S.E.
Advisors
Bethel, Purdue University.
Subject Area
Civil engineering|Remote sensing
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