Open-source GIS application for UAV photogrammetry based on MicMac

Abstract

ABSTRACTRemote-sensing applications using the remotely piloted aerial system (RPAS) are becoming more frequent. RPAS is used in different contexts and in several areas, such as environmental studies, cultural heritage, civil engineering, forestry, and cartography. To process the images resulting from the RPAS, different types of image-based 3D modelling software (proprietary or open source) are used. MicMac is an open-source software which allows generating georeferenced information which can be manipulated or visualized under a geographical information system (GIS) environment. So, the integration between the MicMac procedures within a GIS software could be very useful. The main objective of this work was to create an open-source GIS application based on MicMac photogrammetric tools to obtain the orthophotographs, point clouds, and digital surface models. To test the application developed, two distinct areas were considered: one in a more natural environment (Aguda beach near Porto city, Portugal) and another in an urban environment in the city of Coimbra, Portugal. High-resolution data sets were obtained with a ground sampling distance (GSD) of approximately 4.5 cm. Shaded relief image and dense point cloud were generated. This open-source application can be automated and can create all the files required to run the functionalities from MicMac to obtain the georeferenced information, within a GIS software, bringing photogrammetric data generation to a wider user community. Moreover, integrating this application with the GIS software has several advantages like generating more georeferenced information, such as vegetation indices, or even creating the land use land cover map. Creation of shapefiles with the projection centre of the camera, the area covered by each photograph, and taking account of the number of images that appear in each location are also useful in performing certain tasks.