A constraint-based parameterization technique for B-spline surfaces

Deformation analysis is one of the classical tasks in engineering geodesy. The development of the laser scanner has changed the data acquisition as well as the analysis strategy; instead of point-based approaches, areal ones move into focus. In this paper, a project is presented which aims to develop a spatiotemporal continuous collocation in order to describe areal deformations. The collocation requires among other things the modelling of a deterministic trend which is realized by the estimation of B-spline surfaces in the present study. One of the main challenges in the estimation of such freeform surfaces is the definition of an appropriate parameter form which is in the focus of this contribution. An initial parameterization is obtained by projecting the acquired point cloud onto a base surface called Coons patch. By means of a reparameterization, these initial parameters are improved iteratively. In order to handle irregular point densities, several strategies to introduce boundary constraints into the adjustment are developed, compared and evaluated.