Continuous localization and mapping of a pan–tilt–zoom camera for wide area tracking

Pan–tilt–zoom (PTZ) cameras are well suited for object identification and recognition in far-field scenes. However, the effective use of PTZ cameras is complicated by the fact that a continuous online camera calibration is needed and the absolute pan, tilt and zoom values provided by the camera actuators cannot be used because they are not synchronized with the video stream. So, accurate calibration must be directly extracted from the visual content of the frames. Moreover, the large and abrupt scale changes, the scene background changes due to the camera operation and the need of camera motion compensation make target tracking with these cameras extremely challenging. In this paper, we present a solution that provides continuous online calibration of PTZ cameras which is robust to rapid camera motion, changes of the environment due to varying illumination or moving objects. The approach also scales beyond thousands of scene landmarks extracted with the SURF keypoint detector. The method directly derives the relationship between the position of a target in the ground plane and the corresponding scale and position in the image and allows real-time tracking of multiple targets with high and stable degree of accuracy even at far distances and any zoom level.     

Exploiting distinctive visual landmark maps in pan–tilt–zoom camera networks

Pan–tilt–zoom (PTZ) camera networks have an important role in surveillance systems. They have the ability to direct the attention to interesting events that occur in the scene. One method to achieve such behavior is to use a process known as sensor slaving: one (or more) master camera monitors a wide area and tracks moving targets so as to provide the positional information to one (or more) slave camera. The slave camera can thus point towards the targets in high resolution.In this paper we describe a novel framework exploiting a PTZ camera network to achieve high accuracy in the task of relating the feet position of a person in the image of the master camera, to his head position in the image of the slave camera. Each camera in the network can act as a master or slave camera, thus allowing the coverage of wide and geometrically complex areas with a relatively small number of sensors.The proposed framework does not require any 3D known location to be specified, and allows to take into account both zooming and target uncertainties. Quantitative results show good performance in target head localization, independently from the zooming factor in the slave camera. An example of cooperative tracking approach exploiting with the proposed framework is also presented.     

Virtual wiper — removal of adherent noises from images of dynamic scenes by using a pan–tilt camera

In this paper, we propose a new method that can remove noises from images of dynamic scenes that can cause viewing problems. One of the thorny problems in outdoor surveillance by a camera is that adherent noises such as waterdrops or mud blobs on the protecting glass surface lens disturb the view from the camera. Therefore, we propose a method for removing adherent noises from images of dynamic scenes taken by changing the direction of a pan–tilt camera, which is often used for surveillance. Our method is based on the comparison of two images — a reference image and a second image taken by a different camera angle. The latter image is transformed by a projective transformation and subtracted from the reference image to extract the regions of adherent noises and moving objects. The regions of adherent noises in the reference image are identified by examining the shapes and distances of regions existing in the subtracted image. Finally, regions of adherent noises can be eliminated by merging two images. Experimental results show the effectiveness of our proposed method.     

3D reconstruction of specular surfaces using a calibrated projector–camera setup

Structured light is widely used for shape measurement of beamless surfaces using the triangulation principle. In the case of specular surfaces deflectometry is an appropriate method. Hereby the reflection of a light pattern is observed by a camera. The distortion of the reflected pattern is evaluated to obtain information about the reflecting surface. An important requirement for a 3d reconstruction of a specular surface by deflectometry is a calibrated measurement setup. We propose a method for the overall calibration of a setup consisting of a structured light source, a projection screen and a camera. We consider all extrinsic and intrinsic parameters for the optical mapping including a distortion model for the projector and for the camera, respectively. Given the deflectometric data obtained by the calibrated setup two methods are described which allow the 3d reconstruction of points on a specular surface. This is not trivial as a reconstruction using solely deflectometric data shows ambiguity. In the first method screen displacement between two deflectometric measurements is used to overcome this ambiguity. In the second method curvature-like features on the surface are determined to serve as starting points for a region growing approach. Results of the reconstruction of a specular surface are shown and the performance of the described reconstruction methods are compared to each other.     

Automatically controlled pan–tilt smart camera with FPGA based image analysis system dedicated to real-time tracking of a moving object

This paper presents an intelligent, automatically controlled camera based on visual feedback. The camera housing contains actuators that change the orientation of the camera – enabling a full rotation around the vertical axis (pan) and 90° around the horizontal axis (tilt). A system for acquisition, processing image analysis and a camera driver are implemented in the FPGA Xilinx Spartan-6 device. An original, innovative reconfigurable system architecture has been developed. The FPGA device is connected directly to the eight independently operated SRAM memory banks. A prototype device has been constructed with a real-time tracking algorithm, enabling an automatically control of the position of the camera. The device has been tested indoors and outdoors. The camera is able to keep a tracked object close to the center of its field of view. The power consumption of the control system is 2 W. A reconfigurable part reaches the computing performance of 3200 MOPS.     

Dynamic modeling of SOFC based on a T–S fuzzy model

The operating temperature and voltage are the key parameters affecting the performance of Solid Oxide Fuel Cell (SOFC). In this article a Takagi–Sugeno (T–S) fuzzy model is proposed to describe the nonlinear temperature and voltage dynamic properties of the SOFC system. During the process of modeling, a Fuzzy Clustering Means (FCM) method is used to determine the nonlinear antecedent parameters, and the linear consequent parameters are identified by a recursive least squares algorithm. The validity and accuracy of modeling are tested by simulations. The simulation results show that it is feasible to establish the dynamic model of SOFC by using the T–S fuzzy identification method.     

Dynamic modeling of parallel manipulators based on Lagrange–D’Alembert formulation and Jacobian/Hessian matrices

Multibody System Dynamics - This paper describes the development of a dynamic model for parallel manipulators based on the Lagrange–D’Alembert equation, the Hessian matrix of the...     

Estimating 3D Motion and Forces of Human–Object Interactions from Internet Videos

International Journal of Computer Vision - In this paper, we introduce a method to automatically reconstruct the 3D motion of a person interacting with an object from a single RGB video. Our method...     

CASQUS: A new simulation tool for coupled 3D finite element modeling of tectonic and surface processes based on ABAQUS™ and CASCADE

CASQUS is a numerical simulation tool to model the feedback mechanism between surface and tectonic processes. It includes the surface processes model CASCADE into the finite element solver ABAQUS/Standard?. The finite element method allows for geomechanical simulations of the subsurface with geometrically complex structures in 3D. Additionally, in the commercial software ABAQUS? various types of rheological behavior are already implemented. CASCADE simulates erosion and sedimentation as the combination of fluvial transport and hillslope processes. For the integration of CASCADE into ABAQUS/Standard? an Arbitrary Lagrangian–Eulerian modeling technique is used, which makes a coupled and automated simulation possible. Two benchmark models that are easy to reproduce demonstrate the functionality of CASQUS. Our tool aims at a better understanding of the feedback between mass redistribution at the Earth's surface and processes within a heterogenous subsurface, and at a quantification of the involved processes.     

A hybrid 2D–3D tangible interface combining a smartphone and controller for virtual reality

Virtual Reality - Virtual reality (VR) controllers are widely used for 3D virtual object selection and manipulation in immersive virtual worlds, while touchscreen-based devices like smartphones or...     

A 3D analysis of the joint torques developed during driver's ingress–egress motion

Providing an easy ingress–egress (I/E) movement remains a challenge for car designers. I/E has been largely studied in kinematics, but not in dynamics. This study proposes: (1) to evaluate and describe the motor torques developed in the lower limbs and lumbar joints during I/E motions and (2) to analyse the influence of the car geometry and subject anthropometry. An experiment was performed to observe 15 subjects of three anthropometrical groups getting in and out of a car mock-up simulating three different vehicle configurations. Motor torques were extracted using an inverse dynamics analysis. Both ingress and egress motions were primarily characterised by large torques. Overall, the taller a subject and the lower the seat of the vehicle were, the larger the peak torques were. Moreover, peak torques were higher for egress than ingress. These results are discussed in regard to the current knowledge on I/E ergonomics.     

The reconstruction of a time-dependent source from a surface measurement for full Maxwell’s equations by means of the potential field method

This paper is devoted to the study of an inverse source problem governed by full Maxwell’s equations by means of the potential field method (the $\mathit{A}$-$?$ method). The source term is assumed to be separable in time and space, in which the unknown part is solely time-dependent and is recovered from a surface measurement. We prove that the solution to the inverse problem based on the $\mathit{A}$-$?$ formulation is existing and unique. We suggest a constructive scheme for approximating the solution and discuss its convergence. Finally, a few examples are presented to verify the theoretical results.     

Fast spatial–temporal stereo matching for 3D face reconstruction under speckle pattern projection

Three-dimensional (3D) face reconstruction can be tackled in either measurement-based means or model-based means. The former requires special hardwares or devices, such as structured light setups. This paper addresses 3D face reconstruction by measurement-based means, more specifically a special kind of structured light called space–time speckle projection. Under such a setup, we propose a novel and efficient spatial–temporal stereo scheme towards fast and accurate 3D face recovery. To improve the overall computational efficiency, our scheme consists of a series of optimization strategies including face-cropping-based stereo matching, coarse-to-fine stereo matching strategy applied to face areas, and spatial–temporal integral image (STII) for accelerating the matching cost computation. Based on the results, the proposed scheme is able to reconstruct a 3D face in hundreds of milliseconds on a normal PC, and its performance is validated both qualitatively and quantitatively.     

Graph cut based panoramic 3D modeling and ground truth comparison with a mobile platform – The Wägele

Efficient and comfortable acquisition of large 3D scenes is an important topic for many current and future applications in the field of robotics, factory and office visualization, 3DTV and cultural heritage.In this paper we present both an omnidirectional stereo vision approach for 3D modeling based on graph cut techniques and also a new mobile 3D model acquisition platform where it is employed. The platform comprises a panoramic camera and a 2D laser range scanner for self localization by scan matching. 3D models are acquired just by moving the platform around and recording images in regular intervals. Additionally, we concurrently build 3D models using two supplementary laser range scanners. This enables the investigation of the stereo algorithm’s quality by comparing it with the laser scanner based 3D model as ground truth. This offers a more objective point of view on the achieved 3D model quality.     

Characterization and modeling of the dynamic behavior of a liquid–vapor phase change actuator

The dynamic behavior of a liquid–vapor phase change actuator has been investigated. A modular liquid–vapor phase change actuator was designed and fabricated. The actuator consists of a cavity filled with a two-phase fluid bounded on the bottom by a thin membrane into which heat is added and on the top by a cover slip which is displaced by the expansion of the vapor. A parametric study of geometric and operation parameters was conducted. A lumped parameter mathematical model of the actuator was developed to predict the dynamic behavior of the actuator. The model was validated against measured data. Based on the parameter study, actuators with smaller bubbles experienced higher heat loss. Thicker actuators were associated with higher thermal inertia. Thermal inertia, as well as heat losses, had a major effect on the dynamic behavior of the actuator. The model showed that faster response times and higher sensitivity can be achieved if the thermal inertia and heat loss coefficient values are reduced. Time constants less than 2.5 ms and displacement sensitivity higher than 30 μm/W are feasible.     

Electromechanical modeling and simulation by the Euler–Lagrange method of a MEMS inertial sensor using a FGMOS as a transducer

In this paper, the electromechanical modeling of a differential capacitive sensor interconnected with a floating-gate MOS (FGMOS) transistor is shown; the model was obtained using the Euler–Lagrange theory to analyze this particular physical system used as an inertial sensor. A design methodology is also shown relating all the physical parameters involved, such as: stiffness, damping associated with the capacitive structure, parasitic capacitances present in the transistor, and the maximum operating voltages to avoid pull-in effect. Cases for symmetric and non symmetric differential capacitance comb arrays are analyzed. A model comparison between conventional mass–spring–damper mechanical systems to a specific electromechanical system for capacitive sensor with its associated readout electronics is shown.     

On curvature approximation in 2D and 3D parameter–free shape optimization

Manufacturing constraints considered in shape optimization often need to be expressed in terms of curvature. Within the scope of a sensitivity–based parameter–free shape optimization approach, curvature constraints have to be formulated in terms of the FE node coordinates in order to derive the required first order gradients with respect to the design node coordinates. In this contribution we introduce approaches to approximate the curvature of a FE model using the coordinates of the FE nodes at the boundary of the geometry, as a smooth representation of the design boundary is not available. Therefore, in the 2D case we present two different smooth curves which represent the design boundary and for which the curvature can be computed analytically. In a third 2D, as well as in our 3D approach, we use geometric information of the discretization such as the distance to neighboring boundary nodes and edge normals to approximate the curvature at the respective boundary node under consideration.     

Time and energy modeling of high–performance Level-3 BLAS on x86 architectures

We present accurate piece-wise models for the time and energy costs of high performance implementations of both the matrix multiplication (gemm) and the triangular system solve with multiple right-hand sides (trsm) on x86 architectures. Our methodology decouples the costs due to the floating-point arithmetic/data movement occurring in the higher levels of the cache hierarchy from those of packing/data transfers between the main memory and the L2/L3 cache. A careful analytical study of the data transfers, in combination with an architecture-specific calibration of the costs per operation, render then the components to assemble piece-wise models for the accurate estimation of gemm and trsm’s performance on x86 processors.Our experimental results on an Intel Xeon E5-2620 processor confirm the accuracy of this approach, which reports relative errors for different shapes of gemm and trsm that are, respectively, around 1.5% and 4.5% on average for both time and energy.     

Particle filters and occlusion handling for rigid 2D–3D pose tracking

In this paper, we address the problem of 2D–3D pose estimation. Specifically, we propose an approach to jointly track a rigid object in a 2D image sequence and to estimate its pose (position and orientation) in 3D space. We revisit a joint 2D segmentation/3D pose estimation technique, and then extend the framework by incorporating a particle filter to robustly track the object in a challenging environment, and by developing an occlusion detection and handling scheme to continuously track the object in the presence of occlusions. In particular, we focus on partial occlusions that prevent the tracker from extracting an exact region properties of the object, which plays a pivotal role for region-based tracking methods in maintaining the track. To this end, a dynamical choice of how to invoke the objective functional is performed online based on the degree of dependencies between predictions and measurements of the system in accordance with the degree of occlusion and the variation of the object’s pose. This scheme provides the robustness to deal with occlusions of an obstacle with different statistical properties from that of the object of interest. Experimental results demonstrate the practical applicability and robustness of the proposed method in several challenging scenarios.