Digitale Photogrammetrie in der Bautechnik - Einfluss wichtiger Systemparameter und Genauigkeitspotenzial in der Praxis

Digital photogrammetry in construction engineering - Influence of major system parameters and accuracy potential in applications

Digital close range photogrammetry enables non-contact acquisition of deformations, cracks and other damages from materials, members and building constructions. Strains of concrete and reinforced concrete (ca. 3,5 ‰ ultimate compression strain, ca. 0,1 ‰ ultimate tension strain) and crack widths (from 0,05 mm) are very small compared to other materials. Thus, digital close range photogrammetry often operates on its limits when being applied to concrete structures. The optimal choice of major system parameters decides whether measurements can be accomplished with sufficient accuracy. In a systematic study of relevant system parameters influences and interdependencies were investigated by means of conventional digital photogrammetry equipment. System parameters studied include both the image acquisition process - such as signaling, lighting, exposure, frame rate, object location - and the image analysis parameters - such as size, number and position of facets. Key results are presented and discussed. Finally, recommendations are derived for system parameters in practical application and application limits.