WEB Open Drone Map (WebODM) a Software Open Source to Photogrammetry Process

In the photogrammetric process of the 3D reconstruction of an object or a building, multi-image orientation is one of the most important tasks that often include simultaneous camera calibration. The accuracy of image orientation and camera calibration significantly affects the quality and accuracy of all subsequent photogrammetric processes, such as determining the spatial coordinates of individual points or 3D modeling. In the context of artificial vision, the full-field analysis procedure is used, which leads to the so-called Structure from Motion (SfM), which includes the simultaneous determination of the camera's internal and external orientation parameters and the 3D model. The procedures were designed and developed by means of a photogrammetric system, but the greatest development and innovation of these procedures originated from the computer vision from the late 90s, together with the SfM method. The reconstructions on this method have been useful for visualization purposes and not for photogrammetry and mapping. Thanks to advances in computer technology and computer performance, a large number of images can be automatically oriented in a coordinate system arbitrarily defined by different algorithms, often available in open source software (VisualSFM, Bundler, PMVS2, CMVS, etc. .) or in the form of Web services (Microsoft Photosynth, Autodesk 123D Catch, My3DScanner, etc.). However, it is important to obtain an assessment of the accuracy and reliability of these automated procedures. This paper presents the results obtained from different UAV survey processed with open source software using the Structure from Motion approach WEB OpenDroneMap (WebODM). For the UAV survey we used the Spark DJI has a CMOS sensor of 1 / 2.3” and 12 Mpixel (dimension of the pixel 1.5 micron), FOV 81.9° and focal of 25 mm. Photogrammetric surveys have also been processed with the Metashape commercial software by Agisoft. The results were used as a reference to validate the point clouds coming from WebODM. The validation was done using the Cloud Compare open source software.