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16
Techniques for view transition in multi-camera outdoor environments
- In Proc. Graphics Interface
, 2010
"... Figure 1. A complex outdoor configuration of cameras, illustrating the different relationships between remote cameras and mobile users. For a local camera (L) and a remote camera (R), we classify camera configurations based on the remote camera’s location from the viewer’s point of view, and on the ..."
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Cited by 7 (5 self)
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Figure 1. A complex outdoor configuration of cameras, illustrating the different relationships between remote cameras and mobile users. For a local camera (L) and a remote camera (R), we classify camera configurations based on the remote camera’s location from the viewer’s point of view, and on the scene the remote camera is looking at. Environment monitoring using multiple observation cameras is increasingly popular. Different techniques exist to visualize the incoming video streams, but only few evaluations are available to find the best suitable one for a given task and context. This article compares three techniques for browsing video feeds from cameras that are located around the user in an unstructured manner. The techniques allow mobile users to gain extra information about the surroundings, the objects and the actors in the environment by observing a site from different perspectives. The techniques relate local and remote cameras topologically, via a tunnel, or via bird’s eye viewpoint. Their common goal is to enhance spatial awareness of the viewer, without relying on a model or previous knowledge of the environment. We introduce several factors of spatial awareness inherent to multi-camera systems, and present a comparative evaluation of the proposed techniques with respect to spatial understanding and workload.
Video Quality for Face Detection, Recognition, and Tracking
"... Many distributed multimedia applications rely on video analysis algorithms for automated video and image processing. Little is known, however, about the minimum video quality required to ensure an accurate performance of these algorithms. In an attempt to understand these requirements, we focus on a ..."
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Cited by 6 (3 self)
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Many distributed multimedia applications rely on video analysis algorithms for automated video and image processing. Little is known, however, about the minimum video quality required to ensure an accurate performance of these algorithms. In an attempt to understand these requirements, we focus on a set of commonly used face analysis algorithms. Using standard datasets and live videos, we conducted experiments demonstrating that the algorithms show almost no decrease in accuracy until the input video is reduced to a certain critical quality, which amounts to significantly lower bitrate compared to the quality commonly acceptable for human vision. Since computer vision percepts video differently than human vision, existing video quality metrics, designed for human perception, cannot be used to reason about the effects of video quality reduction on accuracy of video analysis algorithms. We therefore investigate two alternate video quality metrics, blockiness and mutual information, and show how they can be used to estimate the critical video qualities for face analysis algorithms.
An Immersive System for Browsing and Visualizing Surveillance Video
"... HouseFly is an interactive data browsing and visualization system that synthesizes audio-visual recordings from multiple sensors, as well as the meta-data derived from those recordings, into a unified viewing experience. The system is being applied to study human behavior in both domestic and retail ..."
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Cited by 6 (2 self)
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HouseFly is an interactive data browsing and visualization system that synthesizes audio-visual recordings from multiple sensors, as well as the meta-data derived from those recordings, into a unified viewing experience. The system is being applied to study human behavior in both domestic and retail situations grounded in longitudinal video recordings. HouseFly uses an immersive video technique to display multiple streams of high resolution video using a realtime warping procedure that projects the video onto a 3D model of the recorded space. The system interface provides the user with simultaneous control over both playback rate and vantage point, enabling the user to navigate the data spatially and temporally. Beyond applications in video browsing, this system serves as an intuitive platform for visualizing patterns over time in a variety of multi-modal data, including person tracks and speech transcripts.
Geometric Tools for Multicamera Surveillance Systems
- in IEEE International Conference on Distributed Smart Cameras, ACM/IEEE. IEEE
, 2007
"... Our analysis and visualization tools use 3D building geometry to support surveillance tasks. These tools are part of DOTS, our multicamera surveillance system; a system with over 20 cameras spread throughout the public spaces of our building. The geometric input to DOTS is a floor plan and informati ..."
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Cited by 4 (0 self)
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Our analysis and visualization tools use 3D building geometry to support surveillance tasks. These tools are part of DOTS, our multicamera surveillance system; a system with over 20 cameras spread throughout the public spaces of our building. The geometric input to DOTS is a floor plan and information such as cubicle wall heights. From this input we construct a 3D model and an enhanced 2D floor plan that are the bases for more specific visualization and analysis tools. Foreground objects of interest can be placed within these models and dynamically updated in real time across camera views. Alternatively, a virtual first-person view suggests what a tracked person can see as she moves about. Interactive visualization tools support complex camera-placement tasks. Extrinsic camera calibration is supported both by visualizations of parameter adjustment results and by methods for establishing correspondences between image features and the 3D model. Index Terms — surveillance, tracking, deployment support, camera placement, calibration, multiple views, geometric modeling, multicamera systems 1.
State of the art report on video-based graphics and video visualization,”
- Comp. Graph. Forum,
, 2012
"... Abstract In recent years, a collection of new techniques which deal with video as input data ..."
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Cited by 4 (1 self)
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Abstract In recent years, a collection of new techniques which deal with video as input data
Camera Selection for Adaptive Human-Computer Interface
"... Video analytics has become a very important topic in computer vision. This work introduces advanced Video Analytics Human-Computer Interfaces for a Video Surveillance System to ease the tasks of security operators. The visualization of the most relevant views is provided by the HCI module that pre-e ..."
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Cited by 3 (3 self)
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Video analytics has become a very important topic in computer vision. This work introduces advanced Video Analytics Human-Computer Interfaces for a Video Surveillance System to ease the tasks of security operators. The visualization of the most relevant views is provided by the HCI module that pre-emptively activates cameras that will probably cover the motion of interesting objects. Human-Computer Interaction principles has been considered to develop the novel User Interface. Four prototypes have been designed and usability performance has been evaluated exploiting standard methods. Results obtained from such evaluations show the efficiency of the novel information visualization technique.
Pre-Emptive camera activation for Video-Surveillance HCI
"... Abstract. Video analytics has become a very important topic in com-puter vision. Many applications and different approaches have been pro-posed in different fields. This paper introduces a new information vi-sualisation technique that aims to reduce the mental effort of security operators. A video a ..."
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Cited by 1 (1 self)
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Abstract. Video analytics has become a very important topic in com-puter vision. Many applications and different approaches have been pro-posed in different fields. This paper introduces a new information vi-sualisation technique that aims to reduce the mental effort of security operators. A video analytics and a HCI module have been developed to reach the desired goal. Video analysis are exploited to compute possible trajectories used by the HCI module to pre-emptively activate cameras that will be probably interested by the motion of detected objects. The visualisation of most interesting views is provided to reduce the mental effort of human operators and allow them to follow the object of interest. Usability tests show the efficiency of the proposed solution. 1
A Survey on Video-based Graphics and Video Visualization
, 2011
"... In recent years, a collection of new techniques which deal with video as input data, emerged in computer graphics and visualization. In this survey, we report the state of the art in video-based graphics and video visualization. We provide a comprehensive review of techniques for making photo-realis ..."
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Cited by 1 (0 self)
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In recent years, a collection of new techniques which deal with video as input data, emerged in computer graphics and visualization. In this survey, we report the state of the art in video-based graphics and video visualization. We provide a comprehensive review of techniques for making photo-realistic or artistic computer-generated imagery from videos, as well as methods for creating summary and/or abstract visual representations to reveal important features and events in videos. We propose a new taxonomy to categorize the concepts and techniques in this newly-emerged body of knowledge. To support this review, we also give a concise overview of the major advances in automated video analysis, as some techniques in this field (e.g., feature extraction, detection, tracking and so on) have been featured in video-based modeling and rendering pipelines for graphics and visualization.
Virtu4D: a Real-time Virtualization of Reality
"... In video surveillance systems, when dealing with dynamic complex scenes, processing the information coming from multiple cameras and fusing them into a comprehensible environment is a challenging task. This work addresses the issue of providing a global and reliable representation of the monitored e ..."
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In video surveillance systems, when dealing with dynamic complex scenes, processing the information coming from multiple cameras and fusing them into a comprehensible environment is a challenging task. This work addresses the issue of providing a global and reliable representation of the monitored environment aiming at enhancing the perception and minimizing the operator’s effort. The proposed system Virtu4D is based on 3D computer vision and virtual reality techniques and takes benefit from both the ”real ” and the ”virtual ” worlds offering a unique perception of the scene. This paper presents a short overview of the framework along with the different components of the design space: Video Model Layout, Video Processing and Immersive Model Generation. The final interface gathers the 2D information in the 3D context but also offers a complete 3D representation of the dynamic environment allowing a free intuitive 3D navigation. 1.
Masters of Applied Science
, 2009
"... In this thesis, we present the results of a user study that compares three different selection methods for moving targets in 1D and 2D space. The standard Chaseand-Click method involves pursuing an onscreen target with the mouse pointer and clicking on it once directly over it. The novel Click-to-Pa ..."
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In this thesis, we present the results of a user study that compares three different selection methods for moving targets in 1D and 2D space. The standard Chaseand-Click method involves pursuing an onscreen target with the mouse pointer and clicking on it once directly over it. The novel Click-to-Pause method involves first depressing the mouse button to pause all onscreen action, moving the cursor over the target and releasing the mouse button to select it. The Hybrid method combines the initial pursuit with the ability to pause the action by depressing the mouse button, affording an optimization of the point of interception. Our results show that the Click-to-Pause and Hybrid methods results in lower selection times than the Chase-and-Click method for small or fast targets, while the Click-to-Pause technique is the lowest overall for small-fast targets. We integrate the more practical Hybrid method into a multi-view video browser to enable the selection of hockey players in a pre-recorded hockey game. We demonstrate that the majority of correct player selections were performed while the video was paused and that our display method for extraneous information has no effect on selection task performance. We develop a kinematic model that is based on movement speed and direction in 1D as an adjustment to the effective width and distance of a target. Our studies show that target speed assists users when a target is approaching, up to a critical velocity where the direction is irrelevant and speed is entirely responsible for the index of difficulty. In addition, we suggest that existing linear and discrete models of human motor control are inadequate for modeling the selection of a moving target and recommend the minimum jerk law as a guide for measuring human motor acceleration. By combining our empirical results from moving target selection ii tasks in 1D with our theoretical model for motor control, we propose an extension to Fitts ’ Law for moving targets in 2D polar space.
