Accuracy Analysis Of Three-Dimensional Model Reconstructed By Spherical Video Images
Muhammad Irsyadi Firdaus, Jiann-Yeou Rau · Zenodo (CERN European Organization for Nuclear Research) · 2018
Indoor 3D model is useful for navigation purpose and virtual reality applications. However, its surface is usually texture-less with unbalanced illumination situations together with complex architecture design, which is difficult to acquire images and produce the high-quality 3D model. In this study, we propose the use of spherical video images due to its 720 degrees field-of-view (FOV) and its sequential data acquisition is friendly to the user. In order to evaluate its performance, positioning accuracy and feasibility, we also acquire terrestrial laser scanning (TLS) data for comparison and measure ground control points (GCPs) by a total station for accuracy analysis. The Garmin VIRB 360 spherical camera is used to acquire video at 30 fps (frame per second) with an image size of 3840 x 2178. The video is converted to static image sequence with a time interval of 1.23 seconds. The stitched spherical images were imported into Agisoft Photoscan Pro for 3D modeling. The photo triangulation is conduct by Structure-from-Motion (SfM) technique and the positioning accuracy was assessed by GCPs within the Photoscan Pro software. Later, a dense point cloud, mesh model as well as photo-realistic texture model can be produced. The produced dense point cloud was compared with TLS data within CloudCompare software. The experiment result shown that the 3D positioning accuracy (RMSE) after SfM is about 18.9 cm, while the 3D distance discrepancy between the produced dense point cloud with TLS data is about 40.3 cm. The major problem that causes such a large error is the stitching algorithm to create a spherical image does not follow the photogrammetric collinearity condition. It demonstrates that the adoption of Garmin VIRB 360 spherical camera for 3D modeling is beneficial in data acquisition, but its positioning accuracy is too low for high-accuracy applications and may be applicable to indoor navigation applications.