Object tracking and pose estimation using light-field object models

Geometric object models have been widely used for visual object tracking. In this contribution we present particle filter based object tracking with pose estimation using an appearance based lightfield object model. A light-field is an image-based object representation which can be used to render a photo realistic view of an arbitrarily shaped object from arbitrary viewpoints. It is shown how lightfield object models can be generated and utilized. Furthermore, we show how these models fit into the probabilistic framework of dynamic state estimation by defining an appropriate likelihood distribution from an image similarity metric. Finally, we present results and accuracy evaluations from tracking experiments of different objects.

Registration And Feature Extraction From Terrestrial Laser Scanner Point Clouds For Aerospace Manufacturing

Aircraft wing manufacture is becoming increasingly digitalised. For example, it is becoming possible to produce on-line digital representations of individual structural elements, components and tools as they are deployed during assembly processes. When it comes to monitoring a manufacturing environment, imaging systems can be used to track objects as they move about the workspace, comparing actual positions, alignments, and spatial relationships with the digital representation of the manufacturing process. Active imaging systems such as laser scanners and laser trackers can capture measurements within the manufacturing environment, which can be used to deduce information about both the overall stage of manufacture and progress of individual tasks. This paper is concerned with the in-line extraction of spatial information such as the location and orientation of drilling templates which are used with hand drilling tools to ensure drilled holes are accurately located. In this work, a construction grade terrestrial laser scanner, the Leica RTC360, is used to capture an example aircraft wing section in mid-assembly from several scan locations. Point cloud registration uses 1.5"white matte spherical targets that are interchangeable with the SMR targets used by the Leica AT960 MR laser tracker, ensuring that scans are connected to an established metrology control network used to define the coordinate space. Point cloud registration was achieved to sub-millimetre accuracy when compared to the laser tracker network. The location of drilling templates on the surface of the wing skin are automatically extracted from the captured and registered point clouds. When compared to laser tracker referenced hole centres, laser scanner drilling template holes agree to within 0.2mm

The State of the Art in Flow Visualization: Dense and Texture-Based Techniques

Flow visualization has been a very attractive component of scientific visualization research for a long time. Usually very large multivariate datasets require processing. These datasets often consist of a large number of sample locations and several time steps. The steadily increasing performance of computers has recently become a driving factor for a reemergence in flow visualization research, especially in texture-based techniques. In this paper, dense, texture-based flow visualization techniques are discussed. This class of techniques attempts to provide a complete, dense representation of the flow field with high spatio-temporal coherency. An attempt of categorizing closely related solutions is incorporated and presented. Fundamentals are shortly addressed as well as advantages and disadvantages of the methods. Categories and Subject Descriptors (according to ACM CCS): I.3 [Computer Graphics]: visualization, flow visualization, computational flow visualizatio

Patient Specific Surgical Simulation System for Procedures in Colonoscopy

Abstract We have assembled a preliminary environment for simulating tasks that are performed in colonoscopy to provide a professional learning experience. Different commercial endoscopy simulators exist and provide realistic interfaces, but none of these products are able to simulate realistic soft tissue deformations using patient specific preoperative CT or MRI colon datasets. Colon models are represented as deformable objects within physically-based modeling simulation system. The simplified mass-spring system models an object as a collection of point masses connected by linear springs in a mesh structure. We can import patient specific high resolution meshes from MRI and CT abdominal examinations into a system that models objects with different physical properties for interaction with both non-force-feedback and haptic devices. The score tip of the colonoscope with instrument channel, irrigation, lens and light is modeled and the working channel allows interactions with different instruments as an endoscopic biopsy forceps and a snare (lasso tool) for polyp extraction. This virtual reality system for simulating virtual colonoscopy and polyp extraction can be used to simulate diverse procedures on a variety of pathologies in a novel physical environment and hopefully can shorten training periods and reduce complications

Positioning a camera with respect to planar objects of unknown shape by coupling 2D visual servoing and 3D estimations

International audienceThis paper proposes a way to achieve positioning tasks by 2d visual servoing, when the desired image of the observed object cannot be precisely described. The object is assumed to be planar and motionless but no knowledge about its shape or pose is required. First, we treat the case of a threadlike object and then we show how our approach can be generalized to an object with three particular points. The control law is based on the use of 2d visual servoing and on an estimation of two 3d parameters. We show that this control scheme is not sensitive to the calibration of the camera. We conclude this paper by experimental results relative to objects of unknown shape. In addition, an algorithm to estimate the depth between the object and the camera is provided which finally leads a 3d estimation of the object shape