Дослідження точності хмари точок методом наземного лазерного сканування
Date
2019-03-12
Journal Title
Journal ISSN
Volume Title
Publisher
Видавництво Львівської політехніки
Lviv Politechnic Publishing House
Lviv Politechnic Publishing House
Abstract
Виконано експеримент, який полягав у дослідженні хмар точок, а саме їх щільності, інтервалу між точками, змін інтенсивності залежно від зміни відстані та кольору поверхні сканування. Для
досліджень використано наземний лазерний сканер Faro Focus 3D S120. Як тестову марку обрано шліфовану скляну платівку розміром 30×30 см, яку було двічі покрито аерозолем із
білоюматовоюфарбоюз відбивноюздатністю близько 80 % з однієї сторони марки та чорною матовою фарбою з відбивною здатністю близько 20 % з іншої сторони марки. Для виконання
експериментальних робіт тестову марку встановлювали на підставку штатива за допомогою втулки, яка кріпиться до марки. Марку розташовували білою стороною на відстані 0,6 м від наземного
лазерного сканера та виконували сканування. Потім марку обертали чорною стороною та повторювали сканування. Виміри повторювали на відстанях 1,5 м, 3 м, 5 м, 10 м. Загалом отримано 10 сканів.
Значення інтенсивності експортовано з хмари точок за допомогою стандартного програмного забезпечення Faro SCENE. Для оцінювання результатів дослідження проаналізовано графіки
розподілу хмар точок у площинах YX та YZ фрагментів білої та чорної сторін марок, інтенсивності відбитого лазерного випромінювання та стандартне відхилення значень інтенсивності. Подано та
проаналізовано вплив якісно-кількісних характеристик об’єкта сканування на точність побудови хмар точок наземним лазерним сканером Faro Focus 3D S120.
Terrestrial laser scanning is a powerful method for collecting spatial data. This method of remote sensing allows fast, non-contact and precise measurement of objects. Terrestrial laser scanning systems deliver 3D coordinates and the power of the backscattered laser scan signal of each point which registered it as an intensity value. Intensity values are affected by the characteristic of the measured object and the parameters of the environment. The backscattered electromagnetic signal is influenced in its strength by the reflectivity of the scanned object surface, the incidence angle, the distance between laser scanner and object and the atmospheric respectively system specific setting of the TLSmeasurement. Since details about system internal alteration of the signal are often unknown to the user, model driven approaches are impractical. On the other hand, existing data driven calibration procedures require laborious acquisition of separate reference datasets or areas of homogenous reflection characteristics from the field data. Therefore, the impact of qualitative and quantitative characteristics of the scanning object for accuracy investigation of point clouds with the Faro Focus 3D S120 terrestrial laser scanner is the aim of work. Methods. According to the tasks, an experiment was performed, which was to investigation the point clouds: density, interval between points, and intensity changes with distance and color of the scanning object. Faro Focus 3D S120 terrestrial laser scanner was used for the research. As a special test target was chosen a polished glass plate with size 30 cm × 30 cm, which was twice covered with an aerosol with white matte paint with a reflectivity of about 80% on one side of the target and black matte paint with a reflectivity of about 20 % on the other side of the target. To perform the experimental work, the test target was mounted on a tripod using a sleeve that attaches to the target. The target was placed on the white side at a distance of 0.6 m from the terrestrial laser scanner and was scanned. Then the target was turned to the black side and the scanning was repeated. The measurements were repeated at distances of 1.5 m, 3 m, 5 m and 10m. Our test data covers 10 terrestrial scans. The intensity values were exported from the point clouds using Faro SCENE software. Results. The results of the experimental work were considered for the fragments of point clouds of black and white sides of the test target (the size of the fragment is 15´15 points). The distribution of point clouds in the YX and YZ planes of the upper left and center fragments of the white and black sides of the targets, the intensity of the reflected signal and the standard deviation of the intensity values were analyzed. Scientific novelty. The influence of the qualitative and quantitative characteristics of the scanning object on the accuracy of point clouds construction with the Faro Focus 3D S120 laser scanner is presented and analyzed. Practical significance. The study will optimize the choice of terrestrial laser scanning settings based on the properties of the object and the scanning distance.
Terrestrial laser scanning is a powerful method for collecting spatial data. This method of remote sensing allows fast, non-contact and precise measurement of objects. Terrestrial laser scanning systems deliver 3D coordinates and the power of the backscattered laser scan signal of each point which registered it as an intensity value. Intensity values are affected by the characteristic of the measured object and the parameters of the environment. The backscattered electromagnetic signal is influenced in its strength by the reflectivity of the scanned object surface, the incidence angle, the distance between laser scanner and object and the atmospheric respectively system specific setting of the TLSmeasurement. Since details about system internal alteration of the signal are often unknown to the user, model driven approaches are impractical. On the other hand, existing data driven calibration procedures require laborious acquisition of separate reference datasets or areas of homogenous reflection characteristics from the field data. Therefore, the impact of qualitative and quantitative characteristics of the scanning object for accuracy investigation of point clouds with the Faro Focus 3D S120 terrestrial laser scanner is the aim of work. Methods. According to the tasks, an experiment was performed, which was to investigation the point clouds: density, interval between points, and intensity changes with distance and color of the scanning object. Faro Focus 3D S120 terrestrial laser scanner was used for the research. As a special test target was chosen a polished glass plate with size 30 cm × 30 cm, which was twice covered with an aerosol with white matte paint with a reflectivity of about 80% on one side of the target and black matte paint with a reflectivity of about 20 % on the other side of the target. To perform the experimental work, the test target was mounted on a tripod using a sleeve that attaches to the target. The target was placed on the white side at a distance of 0.6 m from the terrestrial laser scanner and was scanned. Then the target was turned to the black side and the scanning was repeated. The measurements were repeated at distances of 1.5 m, 3 m, 5 m and 10m. Our test data covers 10 terrestrial scans. The intensity values were exported from the point clouds using Faro SCENE software. Results. The results of the experimental work were considered for the fragments of point clouds of black and white sides of the test target (the size of the fragment is 15´15 points). The distribution of point clouds in the YX and YZ planes of the upper left and center fragments of the white and black sides of the targets, the intensity of the reflected signal and the standard deviation of the intensity values were analyzed. Scientific novelty. The influence of the qualitative and quantitative characteristics of the scanning object on the accuracy of point clouds construction with the Faro Focus 3D S120 laser scanner is presented and analyzed. Practical significance. The study will optimize the choice of terrestrial laser scanning settings based on the properties of the object and the scanning distance.
Description
Keywords
наземний лазерний сканер, хмара точок, відбиття, інтенсивність, terrestrial laser scanner, point cloud, reflection, intensity
Citation
Глотов В. М. Дослідження точності хмари точок методом наземного лазерного сканування / В. М. Глотов, Х. І. Марусаж // Геодезія, картографія і аерофотознімання. — Львів : Видавництво Львівської політехніки, 2019. — № 90. — С. 41–49.