High-efficiency building surveys by dynamic and static digital images oriented with “mixed models”

Throughout this paper, a method to efficiently survey buildings by digital images, dynamically and statically acquired, is presented by investigating methodological and analytical aspects and by suggesting an integrated surveying procedure, in order to well exploit the synergy among different imaging sensors. At first, it is earlier evaluated and then discarded (for described operative reasons) the idea to use exclusively digital images of a Mobile Mapping System to photogrammetrically survey buildings, exploiting them instead to survey 3D-control points only. In this way, classical topographic measures on the facades are no more required. The original “pseudo-dynamic” model allowing this photogrammetric technique of control point positioning, also with a simplified low cost system, is briefly shown. Afterwards, the digital rectification of static CCD images is investigated, taking into account the effect of coordinate errors in control points measured by MMS. This problem can be suitably overcome thanks to an original mixed model algorithm considering also the prediction of control point coordinate simultaneously to parameter estimation of homographic image transformations. At the end, the testing of this integrated survey method to some historical buildings is presented, as well as the operative problems and limitations occurred. In any case and considering image scales involved, the CCD images so rectified on façades planes have a decimeter accuracy, more than satisfactory for a lot of applications as surveys of aggregate buildings or urban blocks.