Evolutionary computing and particle filtering: a hardware-based motion estimation system

Particle filters constitute themselves a highly powerful estimation tool, especially when dealing with non-linear non-Gaussian systems. However, traditional approaches present several limitations, which reduce significantly their performance. Evolutionary algorithms, and more specifically their optimization capabilities, may be used in order to overcome particle-filtering weaknesses. In this paper, a novel FPGA-based particle filter that takes advantage of evolutionary computation in order to estimate motion patterns is presented. The evolutionary algorithm, which has been included inside the resampling stage, mitigates the known sample impoverishment phenomenon, very common in particle-filtering systems. In addition, a hybrid mutation technique using two different mutation operators, each of them with a specific purpose, is proposed in order to enhance estimation results and make a more robust system. Moreover, implementing the proposed Evolutionary Particle Filter as a hardware accelerator has led to faster processing times than different software implementations of the same algorithm

VIDEO OBJECT TRACKING USING FOREGROUND MODELS

Improvement of object tracking techniques using grab cut an foreground modelsThis Master Thesis present an approach to Video Object Tracking segmentation using foreground models. For the video sequences analysed, the foreground and the background have been modelled using Spatial Colour Gaussian Mixture Models (SCGMMs). SCGMMs are Gaussian Models which describes the foreground and the background using five components in colour and spatial domains. In order to have a better result in the segmentation process, the Gaussian Models computed for each frame are passed to the next frame using a tacking technique that helps in the individuation of the object in foreground alone the sequence. Using the location provided by the tracking, the Gaussian Mixture Model for the background is computed only in the close region around the object in foreground allowing in this way a better modelling of the region. The Thesis is structure as follows: after a presentation of the study of the State of the Art where the techniques for tracking and segmentation are presented, there is the presentation of the method proposed. At the end there is a Chapter that describes the results obtained and some conclusions and a Chapter which presents some future developments

Scale-Adaptive Video Understanding.

The recent rise of large-scale, diverse video data has urged a new era of high-level video understanding. It is increasingly critical for intelligent systems to extract semantics from videos. In this dissertation, we explore the use of supervoxel hierarchies as a type of video representation for high-level video understanding. The supervoxel hierarchies contain rich multiscale decompositions of video content, where various structures can be found at various levels. However, no single level of scale contains all the desired structures we need. It is essential to adaptively choose the scales for subsequent video analysis. Thus, we present a set of tools to manipulate scales in supervoxel hierarchies including both scale generation and scale selection methods. In our scale generation work, we evaluate a set of seven supervoxel methods in the context of what we consider to be a good supervoxel for video representation. We address a key limitation that has traditionally prevented supervoxel scale generation on long videos. We do so by proposing an approximation framework for streaming hierarchical scale generation that is able to generate multiscale decompositions for arbitrarily-long videos using constant memory. Subsequently, we present two scale selection methods that are able to adaptively choose the scales according to application needs. The first method flattens the entire supervoxel hierarchy into a single segmentation that overcomes the limitation induced by trivial selection of a single scale. We show that the selection can be driven by various post hoc feature criteria. The second scale selection method combines the supervoxel hierarchy with a conditional random field for the task of labeling actors and actions in videos. We formulate the scale selection problem and the video labeling problem in a joint framework. Experiments on a novel large-scale video dataset demonstrate the effectiveness of the explicit consideration of scale selection in video understanding. Aside from the computational methods, we present a visual psychophysical study to quantify how well the actor and action semantics in high-level video understanding are retained in supervoxel hierarchies. The ultimate findings suggest that some semantics are well-retained in the supervoxel hierarchies and can be used for further video analysis.PhDComputer Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133202/1/cliangxu_1.pd

Region-based particle filter for video object segmentation

We present a video object segmentation approach that extends the particle filter to a region-based image representation. Image partition is considered part of the particle filter measurement, which enriches the available information and leads to a re-formulation of the particle filter. The prediction step uses a co-clustering between the previous image object partition and a partition of the current one, which allows us to tackle the evolution of non-rigid structures. Particles are defined as unions of regions in the current image partition and their propagation is computed through a single co-clustering. The proposed technique is assessed on the SegTrack dataset, leading to satisfactory perceptual results and obtaining very competitive pixel error rates compared with the state-of-the-art methods.Peer Reviewe