Camera Viewpoint Research Articles

Incomplete 3-D multiview representation of video objects

This paper introduces a new form of representation for three-dimensional (3-D) video objects. We have developed a technique to extract disparity and texture data from video objects that are captured simultaneously with multiple-camera configurations. For this purpose, we derive an "area of interest" (AOI) for each of the camera views, which represents an area on the video object's surface that is best visible from this specific camera viewpoint. By combining all AOIs, we obtain the video object plane as an unwrapped surface of a 3-D object, containing all texture data visible from any of the cameras. This texture surface can be encoded like any 2-D video object plane, while the 3-D information is contained in the associated disparity map. It is then possible to reconstruct different viewpoints from the texture surface by simple disparity-based projection. The merits of the technique are efficient multiview encoding of single video objects and support for viewpoint adaptation functionality, which is desirable in mixing natural and synthetic images. We have performed experiments with the MPEG-4 video verification model, where the disparity map is encoded by use of the tools provided for grayscale alpha data encoding. Due to its simplicity, the technique is suitable for applications that require real-time viewpoint adaptation toward video objects.

Err, New Boundaries for Fiction?! ER's 'Live' Episode

Err, New Boundaries for Fiction?! ER's 'Live' Episode

Measuring the angle of attack of beating insect wings: robust three-dimensional reconstruction from two-dimensional images

A robust technique for determining the angle of attack of insect wings from film of free flight has to date proved elusive. This report describes the development of two new methods ­ the Strips and Planes techniques ­ which were designed to overcome some of the limitations experienced in previous studies. The accuracy and robustness of these novel methods were tested extensively using simulated hawkmoth wing outlines generated for a realistic range of wing positions and torsion. The results were compared with those from two existing methods ­ the Symmetry and Landmarks procedures. The performance of the latter technique will be strongly species-dependent; it could not be successfully applied to hawkmoth flight because of practical difficulties in obtaining suitable landmarks. The Planes method was the least successful of the remaining techniques, especially during those phases of the wingbeat when the orientations of the two wings relative to the camera viewpoint were similar. The Symmetry and Strips methods were tested further to investigate the effects on their performance of introducing additional camber or wing motion asymmetry. The results showed clearly that the Strips method should be the technique of choice wherever the axis of wing torsion is close to the longitudinal axis of the wing. The procedure involves the experimenter matching a model wing divided into chordwise strips to the true wing outline digitized from high-speed film. The use of strips rather than the points digitized in previous studies meant that the analysis required only one wing outline to be digitized. Symmetry of motion between the left and right wings is not assumed. The implications of requiring human input to the Strips method, as opposed to the strictly numerical algorithms of the alternative techniques, are discussed. It is argued that the added flexibility that this provides in dealing with images which have typically been recorded in suboptimal conditions outweighs the introduction of an element of subjectivity. Additional observations arising from the use of the Strips analysis with high-speed video sequences of hawkmoth flight are given.

Segmentation of a wrap-around model using an active contour

Segmentation in the past has been applied to single range maps, which are capable of modelling only the part of an object that is visible from the camera viewpoint. In the field of reverse engineering, there is a great need for the segmentation of complete wrap-around object models. In this paper, a new method is presented for segmenting a wrap-around wireframe model, which is created by interpolating and merging multiple range maps. A semi-automatic edge-based approach is used for the segmentation. Surface differential properties are estimated at each point in the model, and curvature extrema are identified as possible edge points. An energy-minimizing active contour is used interactively to link the edge points. The designer defines small closed contours within the regions to be segmented, and the contour is ‘inflated’ until it is trapped by the potentials at the edge points.

Compositing Computer and Video Image Sequences: Robust Algorithms for the Reconstruction of the Camera Parameters

AbstractAugmented reality shows great promises in fields where a simulation in situ would be impossible or too expensive. When mixing synthetic and real objects in the same animated sequence, we must be sure that the geometrical coherence as well as the photometrical coherence is ensured. One major challenge is to compute the camera viewpoint with sufficient accuracy to ensure a satisfactory composition. We especially address this point in this paper using computer vision techniques and robust statistical methods. We prove that such techniques make it possible to compute almost automatically the viewpoint for long video sequences even for bad quality images in outdoor environments. Significant results on the lighting simulation of the bridges of Paris are shown.

境界線の傾斜角に関する拘束条件を用いた直線通路上の視点位置計測

This paper proposes a method to measure the position of the view point of single camera on a straight passage with constraint conditions of the inclination of the boundary lines. Taking account of the conditions, this method obtains the vanishing point and the perspective translated boundary lines from the 2D-image directly without the binalization processing, and shows good results for the vehicle navigation in the case that the disturbances exist on the passage.

Error recovery in the assembly of a Self-Organizing Manipulator by using active visual and force sensing

This paper deals with the assembly of aSelf-OrganizingManipulator (SOM) by using the method ofActive Sensing. We set a 6-axis force/torque sensor in the wrist of a manipulator and a CCD camera in the hand of another manipulator. By cooperation of hand and eye, human beings can do a variety of versatile work. The eyes guide the motion of the hand, while the hand moves to make the object easy to see. We try to construct a system working in the same way as a human being. We integrate a vision system, a manipulator, and a force/torque sensor into a hand-eye working system. The scene simplification is based on the controlled motion of camera and manipulator. A method of theAverage Visible Ratio (AVR) is proposed to evaluate the viewpoint of the movable camera. A strategy for planning the assembly is presented. The efficiency of the system is illustrated by experiments.

A Study on a Dynamically Reconfigurable Robotic System. 14th Report. Error Recovery in Assembly of Self-Organizing Manipulator Using Active Visual and Force Sensing.

In this report, the method of active sensing is applied to assembly work of a self-organizing manipulator which we introduced in previous research. We placed a 6 axis force/torque sensor in the wrist of the manipulator and a CCD camera into the hand of another manipulator. With cooperation of hand and eye, haman beings can perform a variety of versatile tasks. The eyes guide the motion of the hand, while the hand moves to make the object more easily seen. We attempt to construct a system which works in the same way as a human being. In assembly work, many types of contact status of cells are analyzed. The scene simplification is based on the cooperative motion of the camera and manipulator. We integrate a vision system, a manipulator, and force/torque in to a hand-eye working system. The method of average visible rate is proposed to evaluate the viewpoint of thc camera. A strategy for planning the assembly work is presented for the cellular type of self-organizing manipulator system. The efficiency of the proposed system is shown by experiments.

The Recovery of Three-Dimensional Structure from Image Curves

A class of inferences is described which allows the recovery of three-dimensional structures from the two-dimensional curves in an image. Unlike most previous methods, these inferences do not require restrictive assumptions or prior knowledge regarding the scene. They are based on the assumption that the camera viewpoint and the positions of the illumination sources are independent of the objects in the scene. From these independence assumptions, it can be shown that many potential interpretations of image curves are highly improbable. By eliminating these improbable interpretations it is possible to segment the image into sets of related image features and derive many three-space relations.

The shifting camera point of view and “model of language” in Wiseman'shigh school

The shifting camera point of view and “model of language” in Wiseman'shigh school