A new approach for geo-monitoring using modern total stations and RGB + D images

•Geo-monitoring by using modern total stations/Image Assisted Total Stations.•Detailed description of pixel – theodolite angle relation.•Combined analysis of image and distance data by RGB + D images.•Every RGB + D pixel can directly be expressed as 3D world coordinate.•Results are 3D displacement vectors, tested for statistical significance.

The objective of this study is to present a new approach to geo-monitoring. The approach is based on a combination of different existing as well as established methods while resolving present disadvantages. Herein, RGB + D images are used for a fused data analysis of scan and image data acquired by a single instrument. The used Image Assisted Total Station (IATS) – a multi-sensor system – is presented in detail, with particular focus on the integrated camera system. This includes an improved matrix based notation for the pixel angle relation.The main feature of the analysis is a combination of point cloud and image data, which complement each other very well for monitoring tasks. The data is acquired in subsequent measurement epochs wherein RGB + D images are generated. As a result, any pixel position can be expressed as a polar measurement and transformed into a 3D world coordinate. With the help of image matching algorithms corresponding points/regions of two epochs can be found and displacement vectors calculated.The single processing steps are explained and the practical usage is demonstrated by an application example.