A unified framework for content-aware view selection and planning through view importance

In this paper we present new algorithms for Next-Best-View (NBV) planning and Image Selection (IS) aimed at image-based 3D reconstruction. In this context, NBV algorithms are needed to propose new unseen viewpoints to improve a partially reconstructed model, while IS algorithms are useful for selecting a subset of cameras from an unordered image collection before running an expensive dense reconstruction. Our methods are based on the idea of view importance: how important is a given viewpoint for a 3D reconstruction? We answer this by proposing a set of expressive quality features and formulate both problems as a search for views ranked by importance. Our methods are automatic and work directly on sparse Structure-from-Motion output. We can remove up to 90% of the images and demonstrate improved speed at comparable reconstruction quality when compared with state of the art on multiple datasets

Overlapping camera clustering through dominant sets for scalable 3D reconstruction

In this work we present a method for clustering large unordered sets of cameras. Our method uses camera view information available from Structure-from-Motion (SfM) for computing a set of overlapping clusters suited for Multi-View Stereo (MVS) reconstruction. Our formulation of the problem uses the game theoretic model of dominant sets to find competing clustering solutions with computational simplicity. The overlapping solutions ensure more robust partial reconstructions. Experimental evaluations show that our method produces more regular cluster and overlap configurations with respect to the state of the art. This allows more scalable and higher quality reconstructions, while speeding up 6 times with respect to a MVS which uses all images at once. c 2013.Mauro M., Riemenschneider H., Van Gool L., Leonardi R., ''Overlapping camera clustering through dominant sets for scalable 3D reconstruction'', 24th British machine vision conference - BMVC 2013, 11 pp., September 9-13, 2013, Bristol, United Kingdom.status: publishe

Ice measurement on the wind turbines' blades by close-range photogrammetry methods

Photogrammetric scanning for measuring the thickness of ice is quite new in the wind energy field. When the rotor blades were mounted on the wind turbine tower, ice thickness inspections became nearly impossible to be performed in the past but by image base modeling methods, geometry extraction of ice of frosted blades are possible in the form of mesh models. In this research thesis, 3D model of wind turbine blades without ice is designed as reference Master CAD data. A prototype of this CAD model is made by a 3D printer machine which after painting, a pattern of retro targets is added to blades surfaces. Digital Single-Lens Reflex (SLR) camera is used to capture several images of objects with different modes of lighting and illumination. A series of point clouds is produced by using the Structure from Motion (SfM) method and VisualSfM software. Each point cloud has an arbitrary coordinate system that is scaled and transferred to Global Coordinate System by 3D transform on CATIA software based on similar features between 3D point cloud and master CAD data. When the ice has sufficient texture, such as rime ice and the texture is captured in the images, a point cloud corresponding to the captured region will also be detected. The position of ice on the blades is detected by coded retro targets on blade’s surface and the order of image acquisition. The generated point cloud and its mesh are compared with the Master CAD or reference geometric model and finally shows in 3D format, the shape, thickness and approximate mass of ice on the blades. This study focused on the feasibility of reconstruction of 3D polygonal mesh models by images captured from a wind turbine blade with a configuration of digital SLR cameras. The main objective of this reconstruction is to identify the volume and shape of ice-accumulated areas on the wind turbine blades in arctic regions. Geometrical comparison of these triangular mesh models with the non-iced blade CAD data could reveal the geometry of accumulated ice