The so-called Real Time Kinematic (RTK) option, which allows one to determine with cm-level accuracy the Unmanned Aerial Vehicles (UAV) camera position at shooting time, is also being made available on medium- or low-cost drones. It can be foreseen that a sizeable amount of UAV surveys will be soon performed (almost) without Ground Control Points (GCP). However, obstacles to Global Navigation Satellite Systems (GNSS) signal at the optimal flight altitude might prevent accurate retrieval of camera station positions, e.g., in narrow gorges. In such cases, the master block can be georeferenced by tying it to an (auxiliary) block flown at higher altitude, where the GNSS signal is not impeded. To prove the point in a worst case scenario, but under controlled conditions, an experiment was devised. A single strip about 700 m long, surveyed by a multi-copter at 30 m relative flight height, was referenced with cm-level accuracy by joint adjustment with a block flown at 100 m relative flight height, acquired by a fixed-wing UAV provided with RTK option. The joint block orientation was repeated with or without GCP and with pre-calibrated or self-calibrated camera parameters. Accuracy on ground was assessed on a fair number of Check Points (CP). The results show that, even without GCP, the precision is effectively transferred from the auxiliary block projection centres to the object point horizontal coordinates and, with a pre-calibrated camera, also to the elevations.


    Access

    Download


    Export, share and cite



    Title :

    Indirect UAV strip georeferencing by on-board GNSS data under poor satellite coverage



    Publication date :

    2019-01-01



    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English



    Classification :

    DDC:    629



    Accuracy Assessment of Direct Georeferencing for Photogrammetric Applications Based on UAS-GNSS for High Andean Urban Environments

    Rolando Salas López / Renzo E. Terrones Murga / Jhonsy O. Silva-López et al. | DOAJ | 2022

    Free access

    Georeferencing raster maps using vector data: A meteorological application

    Raffa, Mario / Mercogliano, Paola / Galdi, Carmela | IEEE | 2016


    Georeferencing of condition information from railway infrastructure

    Johannes, Lars / Almeida, Eduardo C. V. | German Aerospace Center (DLR) | 2015

    Free access

    Automatic georeferencing of images acquired by UAV’s

    Hemerly, E. M. | British Library Online Contents | 2014