The reliability assessment of the tls registration methods - The case study of the Royal Castle in Warsaw

Modern measurement technologies are commonly applied to monitor and preserve the cultural heritage as it is an integral part of modern societies. The Terrestrial Laser Scanning (TLS) method is one of the common technologies investigated by the researchers for accurate data acquisition and processing required for architectural documentation. In recent years, many methods were developed for TLS data registration to improve the processing time and accuracy of the bundle adjustment. The aim of this research is to compare the existing TLS target-based registration methods and compare them with the proposed novel method based on the reliability assessment- the robustness analysis. The novel feature-based approach also includes 2D detectors, which were applied to the TLS data converted into spherical images. Measurements were carried out at the Royal Castle in Warsaw using TLS Z+F 5006H and total station Leica TCRP1202. The collected data was analysed using existing software Z+F LaserControl, LupoScan and developed the application to perform 2D + 1H / 3D registration. The main results demonstrated that the proposed method for TLS registration removed the outliers that could not be eliminated by the deviation analysis on control and check points. The accuracy of TLS registration increased with a RMSE difference between 0.1mm and 3.7mm in comparison to existing methods. Furthermore, the accuracy of the results from 2D detectors was improved with relative orientation RMSE≤2.1mm and equivalent for control and check points for X, Y, and Z coordinates in comparison to target-based registration.