一种改进的基于切片的可视面片选择方法

在三维场景处理中,如何快速选择可见面片是提高场景显示速度的关键。基于切片的可视面片选择方法能够有效地减少选择可见面片时的计算量,但是该算法的计算结果是基于直线的视线传达,无法真实再现人眼的视角特征。本人提出了基于切片的一种改进算法,能够快速的计算出上层切片可视部分在下层切片上的投影边界,实现了切片算法的视角改进。     

ONVIF规范在四川电网视频监控系统的应用扩展

在四川电网视频监控系统中IP摄像机与视频处理单元之间的通信采用ONVIF协议。ONVIF规范已涉及设备发现、设备管理等十余项内容。考虑到电力行业的实际需求以及智能化应用的需要,四川电力规范在ONVIF 2.2版本的基础上进行了扩展,扩展的内容包括OSD配置、遮挡告警、3D定位。     

视差信息辅助的视频修补方法

提出一种视差信息辅助的街景视频修补方法,首先通过视差图像的分割检测出视频帧中的待修补区域和参考区域,然后同样基于视差信息建立两者的位置对应关系。在具体修补过程中,按照一种摄像机运动相关的修补顺序,采用渐进迭代的策略对整段视频进行修补,最后得到较满意的效果。由于视差信息代表图像之间像素级的位置对应关系,因此该方法的修补效果不受限于场景的复杂度。同时实验证明文中方法能完成较大面积遮挡区域的修补。     

Effects of device obtrusion and tool-hand misalignment on user performance and stiffness perception in visuo-haptic mixed reality

The Visuo-Haptic Mixed Reality (VHMR) is a branch of the Mixed Reality (MR) that is acquiring more and more interest in the recent years. Its success is due to the ability of merging visual and tactile perceptions of both virtual and real objects with a collocated approach. Like any emerging technology, the development of the VHMR systems is accompanied by challenges that, in this case, deals with the efforts to enhance the multi-modal human perception with the user-computer interface and interaction devices at the moment available.This paper deals with two of the typical problems related to VHMR systems, that are device obtrusion and tool–hand misalignment, and suggests solutions whose effectiveness has been tested by means of user studies.First, the paper analyzes the obtrusion problem and the benefits that users may gain performing task in a mixed environment with unobstructed haptic feedback, performed by means of a novel technique. Secondly, it investigates the effects of tool–hand misalignment on user perception and verifies the efficacy of a proposed misalignment correction technique by means of a comparative user test.Experimental results show that users would benefit from using the proposed unobstructed visuo-haptic approach and the misalignment compensation technique. These enhancements demonstrate the efficacy of the proposed solutions and at the same time get stronger the awareness that obtrusion and misalignment problems are fundamental issues to take into account for producing a realistic perception of a visuo-haptic mixed environment.     

Particle occlusion and mechanical properties of Ni–Al2O3 nanocomposites

Polycrystalline alumina, doped with MgO below the solubility limit, was reinforced with sub-micron particles of Ni by infiltration of Ni-nitrate into fired alumina green bodies, followed by reduction and sintering. The Ni particle size and location were monitored both after reduction and after sintering by transmission electron microscopy. Particle occlusion was found to increase with sintering time and temperature, and is correlated with experimentally detected Mg segregation to the Ni–alumina interfaces, resulting in partial depletion of Mg at the alumina grain boundaries and thus their increased mobility. Occlusion of Ni particles reduces the fracture strength and Weibull modulus of the composites, indicating that particle location is a key microstructural parameter for reaching high fracture strengths, and that this can be controlled via grain boundary and interface adsorption.     

A grid-based Bayesian approach to robust visual tracking

Visual tracking encompasses a wide range of applications in surveillance, medicine and the military arena. There are however roadblocks that hinder exploiting the full capacity of the tracking technology. Depending on specific applications, these roadblocks may include computational complexity, accuracy and robustness of the tracking algorithms. In the paper, we present a grid-based algorithm for tracking that drastically outperforms the existing algorithms in terms of computational efficiency, accuracy and robustness. Furthermore, by judiciously incorporating feature representation, sample generation and sample weighting, the grid-based approach accommodates contrast change, jitter, target deformation and occlusion. Tracking performance of the proposed grid-based algorithm is compared with two recent algorithms, the gradient vector flow snake tracker and the Monte Carlo tracker, in the context of leukocyte (white blood cell) tracking and UAV-based tracking. This comparison indicates that the proposed tracking algorithm is approximately 100 times faster, and at the same time, is significantly more accurate and more robust, thus enabling real-time robust tracking.     

Feature-based detection and correction of occlusions and split of video objects

This paper proposes a novel algorithm for the real-time detection and correction of occlusion and split in object tracking for surveillance applications. The paper assumes a feature-based model for tracking and is based on the identification of sudden variations of spatio-temporal features of objects to detect occlusions and splits. The detection is followed by a validation stage that uses past tracking information to prevent false detection of occlusion or split. Special care is taken in case of heavy occlusion, when there is a large superposition of objects. For the detection of splits, in addition to the analysis of spatio-temporal changes in objects’ features, our algorithm analyzes the temporal behavior of split objects to discriminate between errors in segmentation and real separation of objects, such as in a deposit event. Both objective and subjective experimental results show the ability of the proposed algorithm to detect and correct, both, split and occlusion of objects. The proposed algorithm is suitable in video surveillance applications due to its good performance in multiple, heavy, and total occlusions, its ability to differentiate between real object separation and faulty object split, its handling of simultaneous occlusion and split events, and its low computational complexity. The algorithm was integrated into an on-line video surveillance system and tested under several conditions with promising results. This work was partially supported by the National Science and Engineering Research Council of Canada (NSERC).     

硒硫化镉包裹颜料制备工艺及其发展

分析了硒硫化镉发色体由硅酸锆晶体裹形成的过程,讨论了目前所采用的化学法制备包颜料包裹效率低,发色浅谈的主要原因,提出了用ＳＨＳ法制备提高包效率的新途径。     

Subspace position measurement in the presence of occlusion

An eigenspace-based method for measuring camera and/or object position in the presence of occlusions is described. Following the formation of a global eigenspace during a training phase, input images are divided into subsections for which a local set of projections is stored. Local occlusions in each subsection are detected by eigenspace reconstruction error. Only unoccluded subsections are then recombined dynamically to implement the nearest-neighbor search of the manifold and to avoid ambiguity in the subspace. Experimental results are described to demonstrate this technique for the measurement of the position of two metallic parts in the presence of significant occlusion.     

2D human body tracking with Structural Kalman filter

Tracking moving objects is one of the most important techniques in motion analysis and understanding, and it has many difficult problems to solve. Especially, estimating and identifying moving objects, when the background and moving objects vary dynamically, are very difficult. It is possible under such a complex environment that targets may disappear totally or partially due to occlusion by other objects. The Kalman filter has been used to estimate motion information and use the information in predicting the appearance of targets in the succeeding frames. In this paper, we propose another version of the Kalman filter, to be called Structural Kalman filter, which can successfully work its role of estimating motion information under such a deteriorating condition as occlusion. Experimental results show that the suggested approach is very effective in estimating and tracking non-rigid moving objects reliably.