• Object-based three-dimensional X-ray imaging

      Benjamin, Ralph; Prakoonwit, Simant; Matalas, I.; Kitney, R.I.; Imperial College of Science, Technology and Medicine (Kluwer Academic Publishers, 1996-11)
      A form of three-dimensional X-ray imaging, called Object 3-D, is introduced, where the relevant subject material is represented as discrete 'objects'. The surface of each object is derived accurately from the projections of its outline, and of its other discontinuities, in about ten conventional X-ray views, distributed in solid angle. This technique is suitable for many applications, and permits dramatic savings in radiation exposure and in data acquisition and manipulation. It is well matched to user-friendly interactive displays.
    • Occluded feature exploration for direct volume rendering

      Zhou, Zhiguang; Tao, Yubo; Lin, Hai; Dong, Feng; Clapworthy, Gordon J. (2012)
    • Octree rasterization: accelerating high-quality out-of-core GPU volume rendering

      Liu, Baoquan; Clapworthy, Gordon J.; Dong, Feng; Prakash, Edmond C.; University of Bedfordshire (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2012-08-10)
      We present a novel approach for GPU-based high quality volume rendering of large out-of-core volume data. By focusing on the locations and costs of ray traversal, we are able to significantly reduce the rendering time over traditional algorithms. We store a volume in an octree (of bricks); in addition, every brick is further split into regular macro-cells. Our solutions move the branch-intensive accelerating structure traversal out of the GPU raycasting loop and introduce an efficient empty-space culling method by rasterizing the proxy geometry of a view-dependent cut of the octree nodes. This rasterization pass can capture all of the bricks that the ray penetrates in a per-pixel list. Since the per-pixel list is captured in a front-to-back order, our raycasting pass needs only to cast rays inside the tighter ray segments. As a result, we achieve two levels of empty space skipping: the brick level and the macro-cell level. During evaluation and testing, this technique achieved 2 to 4 times faster rendering speed than a current state-of-the-art algorithm across a variety of data sets.
    • Omnidirectional Holoscopic 3D content generation using dual orthographic projection

      Swash, M.R.; Aggoun, Amar; Fatah, O. Abdul; Li, B.; Fernandez, Juan C. J.; Tsekleves, Emmanuel; Brunel University; University of Bedfordshire (IEEE, 2013-06)
      In recent years there has been a considerable amount of development work been made in the area of Three-Dimensional (3D) imaging systems and displays. Such systems have attracted the attention and have been widely consumed by both home and professional users in sectors such as entertainment and medicine. However, computer generated 3D content remains a challenge as the 3D scene construction requires contributions from thousands of micro images “also known as elemental images”. Rendering microlens images is very time-consuming because each microlens image is rendered by a perspective or orthographic pinhole camera in a computer generated environment. In this paper we propose and present the development of a new method to simplify and speed-up the rendering process in computer graphics. We also describe omnidirectional 3D image recoding using a two-layer orthographic camera. Results show that it's rendering performance makes it an ideal candidate for real-time/interactive 3D content visualization application(s).
    • Opacity volume based halo generation for enhancing depth perception

      Tao, Yubo; Lin, Hai; Dong, Feng; Clapworthy, Gordon J. (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2011-09)
    • Optimal 3D surface reconstruction from multiview photographic images

      Prakoonwit, Simant; Benjamin, Ralph (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2009-11)
      This paper describes a new method for reconstructing 3D surface using a small number, e.g. 10, of 2D photographic images. The images are taken at different viewing directions by a perspective camera with full prior knowledge of the camera configurations. The reconstructed object's surface is represented as a set of triangular facets. We empirically demonstrate that if the viewing directions are uniformly distributed around the object's viewing sphere, then the reconstructed 3D points optimally cluster closely on the highly curved part of the surface and are widely spread on smooth or flat parts. The advantage of this property is that the reconstructed points along a surface or a contour generator are not under sampled or underrepresented because surfaces or contours should be sampled or represented with more densely points where their curvatures are high. The more complex the contour's shape, the greater the number of points is automatically generated by the proposed method. Given that the viewing directions are uniformly distributed, the number and distribution of the reconstructed points depend on the shape or the curvature of the surface regardless of the size of the surface of the object.
    • Parallel centerline extraction on the GPU

      Liu, Baoquan; Telea, Alexandru C.; Roerdink, Jos B.T.M.; Clapworthy, Gordon J.; Williams, David; Yang, Po; Dong, Feng; Codreanu, Valeriu; Chiarini, Alessandro; University of Bedfordshire; et al. (Elsevier, 2014-03-12)
      Centerline extraction is important in a variety of visualization applications including shape analysis, geometry processing, and virtual endoscopy. Centerlines allow accurate measurements of length along winding tubular structures, assist automatic virtual navigation, and provide a path-planning system to control the movement and orientation of a virtual camera. However, efficiently computing centerlines with the desired accuracy has been a major challenge. Existing centerline methods are either not fast enough or not accurate enough for interactive application to complex 3D shapes. Some methods based on distance mapping are accurate, but these are sequential algorithms which have limited performance when running on the CPU. To our knowledge, there is no accurate parallel centerline algorithm that can take advantage of modern many-core parallel computing resources, such as GPUs, to perform automatic centerline extraction from large data volumes at interactive speed and with high accuracy. In this paper, we present a new parallel centerline extraction algorithm suitable for implementation on a GPU to produce highly accurate, 26-connected, one-voxel-thick centerlines at interactive speed. The resulting centerlines are as accurate as those produced by a state-of-the-art sequential CPU method [40], while being computed hundreds of times faster. Applications to fly through path planning and virtual endoscopy are discussed. Experimental results demonstrating centeredness, robustness and efficiency are presented.
    • Performance analysis of a generalized and autonomous DRX scheme

      Liu, Enjie; Ren, Weili; University of Bedfordshire (IEEE, 2014-07-15)
      A generalized and autonomous DRX (discontinuous reception) scheme, applicable to both 3GPP and IEEE 802.16e standards, is analyzed by two - level Markov chain modeling along with the ETSI packet traffic model. Numerical analysis showed that this scheme is capable of autonomously adjusting DRX cycle to keep up with changing UE activity level with no signaling overhead increase, thus produces a better tuned DRX operation. Quantitative comparison with the power saving schemes of 3GPP and 802.16e standards demonstrated that it is advantageous over and generalization of these power saving schemes.
    • Performance simulations of moving target search algorithms

      Loh, Peter K. K.; Prakash, Edmond C. (Hindawi, 2009)
      The design of appropriate moving target search (MTS) algorithms for computer-generated bots poses serious challenges as they have to satisfy stringent requirements that include computation and execution efficiency. In this paper, we investigate the performance and behaviour of existing moving target search algorithms when applied to search-and-capture gaming scenarios. As part of the investigation, we also introduce a novel algorithm known as abstraction MTS. We conduct performance simulations with a game bot and moving target within randomly generated mazes of increasing sizes and reveal that abstraction MTS exhibits competitive performance even with large problem spaces.
    • Pre-processing of holoscopic 3D image for autostereoscopic 3D displays

      Swash, M.R.; Aggoun, Amar; Fatah, O. Abdul; Li, B.; Fernandez, Juan C. J.; Alazawi, E.; Tsekleves, Emmanuel; University of Bedfordshire; Brunel University (2013-12)
      Holoscopic 3D imaging also known as Integral imaging is an attractive technique for creating full colour 3D optical models that exist in space independently of the viewer. The constructed 3D scene exhibits continuous parallax throughout the viewing zone. In order to achieve depth control, robust and real-time, a single aperture holoscopic 3D imaging camera is used for recording holoscopic 3D image using a regularly spaced array of microlens arrays, which view the scene at a slightly different angle to its neighbour. However, the main problem is that the microlens array introduces a dark borders in the recorded image and this causes errors at playback on the holoscopic 3D Display. This paper proposes a reference based pre-processing of holoscopic 3D image for autostereoscopic holoscopic 3D displays. The proposed method takes advantages of microlens as reference point to detect amount of introduced dark borders and reduce/remove them from the holoscopic 3D image.
    • Pre-surgery planning in vascular procedures: an introduction to the RT3S project

      Dubini, Gabriele; Guarneri, Maria Renata; Clapworthy, Gordon J.; Katsaounis, Nassos; Lawford, Patricia; Petrakis, Euripides; Rochette, Michel; Silvestro, Claudio; Testi, Debora; Politec. di Milano; et al. (IEEE, 2013-11)
      RT3S is an EU-funded project in an area of e-health - ICT for Patient Safety. Specifically, RT3S is developing a patient-centred, probabilistic model for peripheral stent fatigue-fracture, integrated within a real-time, computer-aided surgery planning application. RT3S will provide advice on fracture risk for individual combinations of patient anatomy and stent design. Alongside the pre-operational software tool, which is addressed mainly to interventional radiologists, RT3S has also developed a training application that will be of benefit to trainee vascular interventionists and engineers in medical device companies. This paper provides an overview of the work performed during nearly three years of project activities and also addresses the motivation leading to RT3S and the expected impact.
    • Precise foreground detection algorithm using motion estimation, minima and maxima inside the foreground object

      Nawaz, Muhammad; Cosmas, John; Lazaridis, Pavlos I.; Zaharis, Zaharias D.; Zhang, Yue; Mohib, Hamdullah; Brunel University; University of Bedfordshire (IEEE, 2013)
      In this paper the precise foreground mask is obtained in a complex environment by applying simple and effective methods on a video sequence consisting of multi-colour and multiple foreground object environment. To detect moving objects we use a simple algorithm based on block-based motion estimation, which requires less computational time. To obtain a full and improved mask of the moving object, we use an opening-and-closing-by-reconstruction mechanism to identify the minima and maxima inside the foreground object by applying a set of morphological operations. This further enhances the outlines of foreground objects at various stages of image processing. Therefore, the algorithm does not require the knowledge of the background image. That is why it can be used in real world video sequences to detect the foreground in cases where we do not have a background model in advance. The comparative performance results demonstrate the effectiveness of the proposed algorithm.
    • Reference based holoscopic 3D camera aperture stitching for widening the overall viewing angle

      Swash, M.R.; Fernandez, Juan C. J.; Aggoun, Amar; Fatah, O. Abdul; Tsekleves, Emmanuel; Brunel University; University of Bedfordshire (IEEE, 2014-07)
      Holoscopic 3D imaging also known as Integral imaging is a promising technique for creating full color 3D optical models that exist in space independently of the viewer. The images exhibit continuous parallax throughout the viewing zone. In order to achieve depth control, robust and real-time, a single aperture holoscopic 3D imaging camera is used for recording holoscopic 3D image using a regularly spaced array of small lenslets, which view the scene at a slightly different angle to its neighbour. However, the main problem the holoscopic 3D camera aperture faces is that it is not big enough for recording larger scene with existing 2D camera sensors. This paper proposes a novel reference based holoscopic 3D camera aperture stitching method that enlarges overall viewing angle of the holoscopic 3D camera in post-production after the capture.
    • The refocusing distance of a standard plenoptic photograph

      Hahne, Christopher; Aggoun, Amar; Velisavljević, Vladan; University of Bedfordshire (IEEE, 2015-06-12)
      In the past years, the plenoptic camera aroused an increasing interest in the field of computer vision. Its capability of capturing three-dimensional image data is achieved by an array of micro lenses placed in front of a traditional image sensor. The acquired light field data allows for the reconstruction of photographs focused at different depths. Given the plenoptic camera parameters, the metric distance of refocused objects may be retrieved with the aid of geometric ray tracing. Until now there was a lack of experimental results using real image data to prove this conceptual solution. With this paper, the very first experimental work is presented on the basis of a new ray tracing model approach, which considers more accurate micro image centre positions. To evaluate the developed method, the blur metric of objects in a refocused image stack is measured and compared with proposed predictions. The results suggest quite an accurate approximation for distant objects and deviations for objects closer to the camera device.
    • Rendering of novel views from photographs using inference in Markov random field

      Dong, Feng; Clapworthy, Gordon J.; Lin, Hai (IET, 2009-12-03)
    • RESTful web service composition: extracting a process model from Linear Logic theorem proving

      Zhao, Xia; Liu, Enjie; Clapworthy, Gordon J.; Ye, Na; Lu, Yueming (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2011-10)
    • A scalable data repository for recording self-managed longitudinal health data of digital patients

      Zhao, Xia; Zhao, Youbing; Ersotelos, Nikolaos; Fan, Dina; Liu, Enjie; Clapworthy, Gordon J.; Dong, Feng; University of Bedfordshire (2013-11)
      This paper presents the proof-of-concept design of the data repository for 4D digital avatars in the MyHealthAvatar project. Taking account of the privacy and legal issues of patient health information, the research generates a set of synthetic data based on publicly available survey data. At the prototype stage, these synthetic data are used in the scenarios of data storage and management. The paper discusses the early proof-of-concept design of the technical stack which enables the storage and query of large scale patients' health data and empowers the future data mining and analysis for health care support. It provides the first stage implementation and the use of it for data analytics.
    • Scene depth extraction from Holoscopic Imaging technology

      Alazawi, E.; Aggoun, Amar; Abbod, M.; Swash, M.R.; Abdul Fatah, O.; Fernandez, Juan C. J.; University of Bedfordshire; Brunel University (IEEE, 2013-10)
      3D Holoscopic Imaging (3DHI) is a promising technique for viewing natural continuous parallax 3D objects within a wide viewing zone using the principle of “Fly's eye”. The 3D content is captured using a single aperture camera in real-time and represents a true volume spatial optical model of the object scene. The 3D content viewed by multiple viewers independently of their position, without 3D eyewear glasses. The 3DHI technique merely requires a single recording that the acquisition of the 3D information and the compactness of depth measurement that is used has been attracting attention as a novel depth extraction technique. This paper presents a new corresponding and matching technique based on a novel automatic Feature-Match Selection (FMS) algorithm. The aim of this algorithm is to estimate and extract an accurate full parallax 3D model form from a 3D Omni-directional Holoscopic Imaging (3DOHI) system. The basis for the novelty of the paper is on two contributions: feature blocks selection and corresponding automatic optimization process. There are solutions for three main problems related to the depth map estimation from 3DHI: uncertainty and region homogeneity at image location, dissimilar displacements within the matching block around object borders, and computational complexity.