This study focused on photogrammetry by unmanned aerial vehicle (UAV) with a GOPRO HERO3 camera at Cishan river. The accuracy assessment was also analyzed. In the past, an UAV system was usually equipped with a high-resolution monocular camera to obtain highly accurate data. This study used a 4K dynamic photogrammetry for obtaining high-resolution land information utilizing a low-priced consumer camera (GOPRO HERO3). The images from the dynamic photogrammetry were obtained rapidly and without interruption, and could be transformed to orthophotos, stereographs, and DSMs by PIX4Dmapper. They can also be used to generate large mosaic pictures and 720-degree panoramic images by other software. The accuracies of the UAV-derived coordinate values in the X, Y and Z directions are 7.5, 4.2 and 12.4 cm, respectively. They all reach the criterions of horizontal accuracy (25 cm) and vertical accuracy (30 cm) of the National Land Surveying and Mapping center (NLSC). Thus,it is feasible to use this method in detecting disaster prevention problems.
Key Words : UAV, Consumer digital cameras, Pix4Dmapper.