Mätosäkerhet vid indirekt längdmätning med laserskanner Leica BLK360

Detta är en Kandidat-uppsats från Högskolan i Gävle/Samhällsbyggnad, GIS

Sammanfattning: The need for 3D-data has increased in the modern society. The data is used in many applications such as terrain models, documentation of buildings and infrastructure and can also be used for restauration or when monitoring deformations. Laser ranging is an important source to collect this type of information. Technical development has contributed with smaller and cheaper units and increased performance. Leica BLK360 was released in 2016 and is an example of this technological upraise. Since the model is new, it is interesting to investigate its performance. The goal of the study was to evaluate the performance of the length measurements by performing indirect measurements, as well as to investigate the range noise. These tests were performed at targets at different range indoors. The study took place at the lab facility at Heimdall at the University of Gävle. The method that was used, was to perform indirect measurements with targets on a line. The targets were placed with approximately 10 m in between. The results of scanned parallel targets were measured, it shows uncertainty that is smallest at 30 m (just over 2 mm) and highest at 40 m (over 5 mm). No statistical differences could be confirmed in this data. When non parallel targets was measured, the calculated uncertainty differences were 2–3 mm at 20–40 m (0° scanning angle). Low uncertainty was measured at 0° scanning angle, at higher angles uncertainties are increased. Differences could only be statistically confirmed on 40 m 45° and 10 m 0°. A conclusion from the investigation is that the measured uncertainties would be larger than if direct measurements was made. The results in this study based off indirect measurements, could not be compared to results made by direct measurements. The uncertainties would however be smaller in this type of study. When investigated the range noise it showed close to a linear curve in different scanning angles, when studying distance at 0–30 m except the target at 10 m. Statistically significant differences could be found for most measurements of range noise. The range noise is not specified in the user manual. The scanner works well at scanning indoor spaces, the low density point cloud at far range could be a limiting factor in some situations.

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