207 research outputs found
Moving object detection strategy for augmented-reality applications in a GPGPU by using CUDA
A spatial-color-based non-parametric background-foreground modeling strategy in a GPGPU by using CUDA is proposed. This strategy is suitable for augmented-reality applications, providing real-time high-quality results in a great variety of scenarios
SELF-ADAPTING PARALLEL FRAMEWORK FOR LONG-TERM OBJECT TRACKING
Object tracking is a crucial field in computer vision that has many uses in human-computer interaction, security and surveillance, video communication and compression, augmented reality, traffic control, etc. Many implementations are introduced in practice, and yet recent methods emphasize on tracking objects adaptively by learning the object’s perspectives and rediscovering it when it becomes untraceable, so that object’s absence problem (in case of occlusion, cluttering or blurring) is resolved. Most of these algorithms have high computational burden on the computational units and need powerful CPUs to attain real-time tracking and high bitrate video processing. These computational units may handle no more than a single video source, making it unsuitable for large-scale implementations like multiple sources or higher resolution videos. In this thesis, we choose one popular algorithm called TLD, Tracking-Learning-Detection, study the core components of the algorithm that impede its performance, and implement these components in a parallel computational environment such as multi-core CPUs, GPUs, etc., also known as heterogeneous computing. OpenCL is used as a development platform to produce parallel kernels for the algorithm. The goals are to create an acceptable heterogeneous computing environment through utilizing current computer technologies, to imbue real-time applications with an alternative implementation methodology, and to circumvent the upcoming limitations of hardware in terms of cost, power, and speedup. We are able to bring true parallel speedup to the existing implementations, which greatly improves the frame rate for long-term object tracking and with some algorithm parameter modification, it provides more accurate object tracking. According to the experiments, developed kernels have achieved a range of performance improvement. As for reduction based kernels, a maximum of 78X speedup is achieved. While for window based kernels, a range of couple hundreds to 2000X speedup is achieved. And for the optical flow tracking kernel, a maximum of 5.7X speedup is recorded. Global speedup is highly dependent on the hardware specifications, especially for memory transfers. With the use of a medium sized input, the self-adapting parallel framework has successfully obtained a fast learning curve and converged to an average of 1.6X speedup compared to the original implementation. Lastly, for future programming convenience, an OpenCL based library is built to facilitate the use of OpenCL programming on parallel hardware devices, hide the complexity of building and compiling OpenCL kernels, and provide a C-based latency measurement tool that is compatible with several operating systems
Vision Pipelines and Optimizations
This chapter explores some hypothetical computer vision pipeline designs to understand HW/SW design alternatives and optimizations. Instead of looking at isolated computer vision algorithms, this chapter ties together many concepts into complete vision pipelines. Vision pipelines are sketched out for a few example applications to illustrate the use of different methods. Example applications include object recognition using shape and color for automobiles, face detection and emotion detection using local features, image classification using global features, and augmented reality. The examples have been chosen to illustrate the use of different families of feature description metrics within the Vision Metrics Taxonomy presented in Chap. 5. Alternative optimizations at each stage of the vision pipeline are explored. For example, we consider which vision algorithms run better on a CPU versus a GPU, and discuss how data transfer time between compute units and memory affects performance.
Document type: Part of book or chapter of boo
Optimizing Harris Corner Detection on GPGPUs Using CUDA
ABSTRACT
Optimizing Harris Corner Detection on GPGPUs Using CUDA
The objective of this thesis is to optimize the Harris corner detection algorithm implementation on NVIDIA GPGPUs using the CUDA software platform and measure the performance benefit. The Harris corner detection algorithm—developed by C. Harris and M. Stephens—discovers well defined corner points within an image. The corner detection implementation has been proven to be computationally intensive, thus realtime performance is difficult with a sequential software implementation. This thesis decomposes the Harris corner detection algorithm into a set of parallel stages, each of which are implemented and optimized on the CUDA platform. The performance results show that by applying strategic CUDA optimizations to the Harris corner detection implementation, realtime performance is feasible. The optimized CUDA implementation of the Harris corner detection algorithm showed significant speedup over several platforms: standard C, MATLAB, and OpenCV. The optimized CUDA implementation of the Harris corner detection algorithm was then applied to a feature matching computer vision system, which showed significant speedup over the other platforms
Tecniche per la rilevazione automatica marker-less di persone e marker-based di robot all'interno di reti di telecamere RGB-Depth
OpenPTrack is a state of the art solution for people detection and tracking, in this work we extended some of the functionalities (detection from highly tilted camera) of the software and introduced new ones (automatic ground plane equation calculator). Also, we test the feasibility and the behaviour of a mobile camera mounted on a people-following robot and dynamically registered in the OPT network through a fiducial cubic marke
Dense Vision in Image-guided Surgery
Image-guided surgery needs an efficient and effective camera tracking system in order to perform augmented reality for overlaying preoperative models or label cancerous tissues on the 2D video images of the surgical scene. Tracking in endoscopic/laparoscopic scenes however is an extremely difficult task primarily due to tissue deformation, instrument invasion into the surgical scene and the presence of specular highlights. State of the art feature-based SLAM systems such as PTAM fail in tracking such scenes since the number of good features to track is very limited. When the scene is smoky and when there are instrument motions, it will cause feature-based tracking to fail immediately.
The work of this thesis provides a systematic approach to this problem using dense vision. We initially attempted to register a 3D preoperative model with multiple 2D endoscopic/laparoscopic images using a dense method but this approach did not perform well. We subsequently proposed stereo reconstruction to directly obtain the 3D structure of the scene. By using the dense reconstructed model together with robust estimation, we demonstrate that dense stereo tracking can be incredibly robust even within extremely challenging endoscopic/laparoscopic scenes.
Several validation experiments have been conducted in this thesis. The proposed stereo reconstruction algorithm has turned out to be the state of the art method for several publicly available ground truth datasets. Furthermore, the proposed robust dense stereo tracking algorithm has been proved highly accurate in synthetic environment (< 0.1 mm RMSE) and qualitatively extremely robust when being applied to real scenes in RALP prostatectomy surgery. This is an important step toward achieving accurate image-guided laparoscopic surgery.Open Acces
Accurate geometry reconstruction of vascular structures using implicit splines
3-D visualization of blood vessel from standard medical datasets (e.g. CT or MRI) play an important role in many clinical situations, including the diagnosis of vessel stenosis, virtual angioscopy, vascular surgery planning and computer aided vascular surgery. However, unlike other human organs, the vasculature system is a very complex network of vessel, which makes it a very challenging task to perform its 3-D visualization. Conventional techniques of medical volume data visualization are in general not well-suited for the above-mentioned tasks. This problem can be solved by reconstructing vascular geometry. Although various methods have been proposed for reconstructing vascular structures, most of these approaches are model-based, and are usually too ideal to correctly represent the actual variation presented by the cross-sections of a vascular structure. In addition, the underlying shape is usually expressed as polygonal meshes or in parametric forms, which is very inconvenient for implementing ramification of branching. As a result, the reconstructed geometries are not suitable for computer aided diagnosis and computer guided minimally invasive vascular surgery. In this research, we develop a set of techniques associated with the geometry reconstruction of vasculatures, including segmentation, modelling, reconstruction, exploration and rendering of vascular structures. The reconstructed geometry can not only help to greatly enhance the visual quality of 3-D vascular structures, but also provide an actual geometric representation of vasculatures, which can provide various benefits. The key findings of this research are as follows: 1. A localized hybrid level-set method of segmentation has been developed to extract the vascular structures from 3-D medical datasets. 2. A skeleton-based implicit modelling technique has been proposed and applied to the reconstruction of vasculatures, which can achieve an accurate geometric reconstruction of the vascular structures as implicit surfaces in an analytical form. 3. An accelerating technique using modern GPU (Graphics Processing Unit) is devised and applied to rendering the implicitly represented vasculatures. 4. The implicitly modelled vasculature is investigated for the application of virtual angioscopy
REAL-TIME DATA MINING FOR PROCESS OPERATIONS USING GRAPHICS PROCESSING UNIT (GPU)-BASED HIGH PERFORMANCE COMPUTING
Ph.DDOCTOR OF PHILOSOPH
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