M.Sc Thesis

M.Sc StudentPostolov Yuri
SubjectAccurate and Reliable Surface Reconstruction Using
Photogrammetry and Laser Altimery
DepartmentDepartment of Civil and Environmental Engineering
Supervisor MR Amnon Krupnik


Laser altimetry has provided a source of elevation information, which is both accurate and spatially dense.  This information is beneficial for the production of visible surface models, especially in areas where traditional photogrammetric methods are unable to provide accurate heights.  Although laser altimetry has many benefits, it also has limitations due to its lack of thematic information and due to calibration errors that may occur during data acquisition.  Therefore, it would be beneficial to use both laser data and photogrammetric data to achieve the best results.  To work with both data sets simultaneously, it must be ensured that the data sets are accurately registered.  In this study an special algorithm was developed for registering surfaces acquired using different methods, and in particular, laser altimetry and photogrammetry .

The surface registration algorithm uses the difference in elevation between the surfaces and the gradients of the surfaces to produce observation equations.  These are solved using an iterative least-squares adjustment.  The transformation parameters that are determined by the algorithm include scale, translations and rotations

Testing was undertaken to assess the capability of the algorithm to accurately register two surfaces.  Initial tests were carried out using synthetic data sets with known transformations.  These tests were useful to show the validity of the algorithm, and also to eliminate any implementation flaws.  The sensitivity of the algorithm to random errors was investigated by introducing such errors to the data sets.  Further testing has been undertaken using airborne laser data and aerial imagery covering an urban site over Ocean City, MD .