@ARTICLE{meidow*09:reasoning, author = "Meidow, Jochen and Beder, Christian and Förstner, Wolfgang", title = "Reasoning with uncertain points, straight lines, and straight line segments in 2D", year = "2009", pages = "125-139", city = "Bonn",}

Well known estimation techniques in computational geometry usually deal only with single geometric entities as unknown parameters and do not account for constrained observations within the estimation. The estimation model proposed in this paper is much more general, as it can handle multiple homogeneous vectors as well as multiple constraints. Furthermore, it allows the consistent handling of arbitrary covariance matrices for the observed and the estimated entities. The major novelty is the proper handling of singular observation covariance matrices made possible by additional constraints within the estimation. These properties are of special interest for instance in the calculus of algebraic projective geometry, where singular covariance matrices arise naturally from the non-minimal parameterizations of the entities. The validity of the proposed adjustment model will be demonstrated by the estimation of a fundamental matrix from synthetic data and compared to heteroscedastic regression [?], which is considered as state-ofthe- art estimator for this task. As the latter is unable to simultaneously estimate multiple entities, we will also demonstrate the usefulness and the feasibility of our approach by the constrained estimation of three vanishing points from observed uncertain image line segments.

@inproceedings{meidow*09:optimal, author={Meidow, J. and F{\" o}rstner, W. and Beder, C.}, title={{Optimal Parameter Estimation with Homogeneous Entities and Arbitrary Constraints}}, booktitle={Pattern Recognition (Symposium of DAGM) '09}, editor = {Denzler, J. and Notni, G.}, year={2009}, publisher = {Springer}, series = {LNCS} }

Automatic quality evaluation of photogrammetric building acquisitions is important to realize deficiencies of acquisition approaches, tocompare different acquisitions approaches and to check the keeping of contractual specifications. For the decision-makers a procedure will be suggested taking a few, good interpretable quality measures into account. Therefore, useful quality measures have to be identifiedby the formulation of criteria. These quantities can be derived from the comparison of a test data set and a reference data set capturing the same scene. The acquired topology is usually uncertain as for instance two adjacent buildings may be acquired as one building ortwo buildings. Thus a screening of the registered area is suggested to compute the quantities. The approach is independent of the used acquisition method. For the application of large data sets the corresponding data structures will be explained. In experimental tests thebuildings registered by two commercial acquisition systems will be compared by the quality measures determined in 2D and 3D.

@inproceedings{meidow*05:voxel-based, author = "Meidow, Jochen and Schuster, Hanns-Florian", title = "Voxel-based Quality Evaluation of Photogrammetic Buildingacquisitions", year = "05", city = "Bonn", proceeding = "Proceedings of the CMRT05-Workshop",}

With the increasing number of cameras the need for plug-and-play calibration procedures arises to realize a subsequent automatic geometric evaluation of observed scenes. An easy calibration procedure is proposed for a non-zooming stationary camera observing objects of initially equal and known heights above a ground plane. The image coordinates of the corresponding foot and head points of these objects serve as observations. For the interior and exterior orientation of the camera a minimal parametrization is introduced with the height of the camera above the ground plane, its pitch and roll angle and the principal distance. With the idea of corresponding foot and head trajectories being homologue, the situation can be reformulated with a virtual second camera observing the scene. Therefore a plane induced homography can be established for the observation model. This special planar homology can be parametrisied with the unknown calibration quantities. Initially the calibration is estimated by observing foot and head points of objects with known heights. In the subsequent evaluation phase the height and positions of unknown objects can be determined. With the same procedure the calibration can be checked and updated if needed. The approach is evaluated with a real scene.

@INPROCEEDINGS{meidow04:calibration, author = {Jochen Meidow}, title = {Calibration of Stationary Cameras by Observing Objects of Equal Heights on a Ground Plane}, booktitle = {Proc. 20th ISPRS Congress, Istanbul, Turkey}, year = {2004}, pages = {1067-1072}, organization = {ISPRS}, pdf = {http://www.ipb.uni-bonn.de/papers/2004/meidow04.calibration.pdf}, }