{'fraction_non_alphanumeric': 0.008944543828264758, 'fraction_numerical': 0.0, 'mean_word_length': 5.431034482758621, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
STRUCTURAL MONITORING OF TUNNELS USING TERRESTRIAL LASER SCANNING

In recent years terrestrial laser scanning is rapidly evolving as a surveying technique for the monitoring of engineering objects like roof constructions, mines, dams, viaducts and tunnels. The advantage of laser scanning above traditional surveying methods is that it allows for the rapid acquisition of millions of scan points representing the whole surface of the object considered. Still it is a big challenge to obtain accuracies and precisions in the millimeter level when quantifying deformation of an object between epochs. This work presents two major steps towards obtaining sub noise level accuracies in surveying applications using terrestrial laser scan data. The first step aims at obtaining a point cloud of optimal quality for each epoch. The second steps consists of an adjustment and testing procedure that identifies deformation by gaining benefit from both data redundancy and individual point quality. The discussion of both steps is illustrated using several examples from mainly tunnel monitoring projects in the Rotterdam area.