Aiding indoor photogrammetry with UWB sensors

Given the worldwide spread of smartphones, photogrammetric surveying with mobile devices is becoming of significant interest in the research community for providing low cost three-dimensional (3D) models. Since the photogrammetric procedure applied to images produces a projective model, some external information is needed in order to obtain a 3D metric model. To this aim, Global Navigation Satellite System (GNSS) measurements are typically aided to the photogrammetric reconstruction procedure. However, the quality of the obtained reconstruction is related to the GNSS positioning accuracy, which is typically at meterlevel for cheap receivers as those embedded in most of the consumer mobile devices, e.g. smartphones. Furthermore, this approach cannot be used in GNSS-denied environments (e.g. indoors). To overcome these issues, this paper investigates the integration of information provided by an Ultra-Wideband (UWB) positioning system with image-based reconstruction to produce a metric reconstruction. Furthermore, the orientation (with respect to North-East directions) of the model is assessed thanks to the use of inertial sensors included in the UWB devices. Results of this integration are shown on two case studies in indoor environments.