Integrated time-space modelling based on correlated measurements for the determination of survey configurations and the description of deformation processes

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This project addresses the analysis of deformation processes with high spatial resolution. The two main objectives are the development of a space-continuous congruency deformation model in order to represent these processes and the implementation of a non-linear sensitivity analysis of this model. The investigations continue the research topics of IMKAD I, but address new topics as well. Two point clouds, representing the geometry of the same object at two discrete points of time and differing in a pure rigid body motion or in a rigid body movement superimposed by local strain, form the project’s basis. The establishment of the deformation model is twofold as it requires a functional as well as a stochastic part. The development of the latter includes the determination of the synthetic covariance matrix of impulse scanners and the continuation of the respective investigations of IMKAD I concerning phase-based scanners, taking new and more realistic findings into account. An available complete reference laboratory showing laser-tracked geometries will be used to verify the results; among other things, a first-time verification of the variance level as well as of the matrix’s correlation structure will be possible. The methodological improvements regarding the deformation model’s functional part concern the qualification of estimated B-spline surfaces for an epochal comparison based on their surface parameters. A joint estimation of surface parameters and control points is necessary and yields to an adaption of the model selection method developed in IMKAD I. Based on these improvements, the grid of surface parameters is used to determine the elements of the rigid body movement. If the rigid body movement is superimposed by local strain, the respective influences have to be separated iteratively by identifying, statistically validating and excluding the distorted areas. The developed methods for point cloud modelling and for deformation analysis are assessed in two ways. On the one hand, they are validated by means of nominal values; on the other hand an evaluation is performed using algorithms which represent the state of the art. Therefore, measurements are performed at three objects with sizes at different scales: a test specimen, a freeform shell and a dam. Furthermore, atmospheric’s spatial and temporal variations can be particularly examined due to the field campaigns.The new deformation model, including rigid body movements as well as three-dimensional strain, leads to a revision of the non-linear sensitivity analysis, especially with respect to the approaches “observation groups” and “piecewise linearization”. Based on these approximations optimal scanner parameters are delivered by a prototype-software. The software will deliver the position of the scanner relative to the object, the scan quality level and the angular sampling rate in a heuristic and automated way.