Abstract
Abstract. Mobile laser scanning (MLS) data are widely used for solving various tasks. To be sure that these data are appropriate for a specific task it is necessary to adjust data with a certain accuracy. Large scale topographic mapping is one from the tasks often solved by MLS data. Necessary accuracy of creating topographic plans is determined with a requirements document. Topographic plans are always created in a certain coordinate system. For this reason, MLS data should be previously transformed in the required one. For transformation control points measured with other more accurate methods should be applied. The quantity of necessary control points depends on a surveying area. For urban areas a lot of control points are required due to bad quality of GNSS signal. Much research has been conducted for these areas. For areas with open view of the sky it is required significantly fewer control points. Moreover, there are not so many vertical objects in areas with open view of the sky. Large errors can take place in the result of automatic adjustment of point cloud’s multi-passes. The results of both relative and absolute MLS data adjustment are given for the area with a good GNSS signal. The paper presents the results of accuracy estimation with different quantity of control points. The main goal of the paper is to determine the minimum number of control points for MLS data to be appropriate for creating topographic plans at a scale of 1:500 with a contour interval of 0.25 m.
Highlights
Mobile laser scanning has become a popular method of surveying all over the world
Mobile laser scanning (MLS) systems are usually equipped with 2 laser scanners, digital cameras, 2 GNSS antennas, an inertial measurement unit (IMU), a distance measurement instrument (DMI), a control unit and an operating computer
As measuring of control point coordinates with terrestrial classical methods is very time-consuming, it is necessary to determine minimum allowed number of control points for MLS data to match the accuracy of large scale topographic mapping
Summary
Mobile laser scanning has become a popular method of surveying all over the world. This method allows gathering data for very short period of time with high accuracy and density. Measuring of GCP coordinates with terrestrial classical methods like a tacheometric survey and a survey using GNSS receivers is very time-consuming In this case application of aerial imagery can reduce the average distance between two control points till 100–200 m instead of using hundred control points along the road collected under field conditions [Gao et al, 2015]. As measuring of control point coordinates with terrestrial classical methods is very time-consuming, it is necessary to determine minimum allowed number of control points for MLS data to match the accuracy of large scale topographic mapping. It should be determined the maximum base-line length between the roving receiver of an MLS system and the reference station for this goal. The study is carried out on the basis of data gathered for roads within oil and gas deposits
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