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Real-time pose estimation and reliable motion control are two crucial tasks for a quadrotor UAV. In order to obtain accurate and robust pose estimation, an estimation algorithm based on Cubature Kalman Filter (CKF) is adopted in this paper. Considering the limitation of a quadrotor working in GPS-denied indoor environments, a sparse optical flow algorithm is utilized in our work to estimate the quadrotor's...
In this essay static background retrieving method is introduced. A new kind of background retrieving & renewing method is proposed based on their limits. By introducing new parameter background weights and their variances each frame will be separately compared with each previous frame and the current background, then the background weights will be adjusted according to their variances so as...
Optical flow estimation is one of the key technologies in computer vision and image processing. However, constancy of the grey value which is used in traditional variational optical flow computation technology is sensitive to the constant changes of illumination and non-translational displacements. To solve this problem, the advanced data terms including the gradient value constancy assumptions and...
The multi-label problem is of fundamental importance to computer vision, yet finding global minima of the associated energies is very hard and usually impossible in practice. Recently, progress has been made using continuous formulations of the multi-label problem and solving a convex relaxation globally, thereby getting a solution with optimality bounds. In this work, we develop a novel framework...
Vision is a natural tool for human-computer interaction, since it provides visual feedback to the user and mimics some human behaviors. It requires however the fast and robust computation of motion primitives, which remains a difficult problem. In this work, we propose to apply some recent mathematical results about convex optimization to the TV-L1 optical flow problem. At the cost of a small smoothing...
The purpose of this study is to examine the means by which multiple wafers may be aligned in order to reduce wafer handling time in wafer processes. We designed a multilevel structure for a prealigner which can simultaneously handle multiple wafers within a system. The system consists of gripping parts, kinematic parts, vacuum chucks, pneumatic units, hall sensors and a DSP controller. The procedure...
Sequential multi-sensor satellite images are used for the computation of mesoscale surface currents in the Northern and Southern Baltic Proper. Different marine surface films and accumulated algae at the water surface are imaged by the sensors working in the optical, infrared, and microwave part of the electromagnetic spectrum and can thus be used as tracers for the local motion of the sea surface...
In this paper we develop a novel approach called the compensated HS (CHS) optical flow estimation algorithm to improve the precision of the large displacement optical flow field. For the lack of the higher order term in the optical flow constraint equation, the traditional optical flow estimation based on the first-order gradient always produce the optical flow field with obvious error in the case...
The ability to fly at low altitude while actively avoiding collisions with the terrain and other objects is a great challenge for small unmanned aircraft. This paper builds on top of a control strategy called optiPilot whereby a series of optic-flow detectors pointed at divergent viewing directions around the aircraft main axis are linearly combined into roll and pitch commands using two sets of weights...
In this paper we develop a robust and discontinuity-preserving approach based on local and global combined model for the optical flow estimation. Firstly, the local and global optical flow methods are combined to yield dense flow fields that are robust against noise. Then a non-linear diffusion is provided to the model for discontinuity-preserving of optical flow boundary. Simultaneously, a coarse-to-fine...
Use of unsuitable techniques and parameters in identifying optical flow movement produces poor segmentation and indirectly affects the optical flow pattern. In this paper, emphasis is focused on the production of optical flow image using Horn Schunck technique and finding the optimum parameters. Image flow movement using Horn Schunck technique and its implementation has been researched to comprehend...
The present study examined age related decrements in the use of optical flow and landmark information for the control of steering. Older and younger drivers were presented with computer generated displays simulating vehicle motion through a random dot ground plane scene and they were asked to steer the vehicle to null out the side wind perturbation. In the first experiment, on half the trials landmark...
This paper focuses on extending the Virtual Cylindrical Screen (VCS) algorithm for detecting stationary objects inside a VCS, when a sensor moves forward along the optical axis. Effect by foveation in use of the VCS algorithm are simulated and discussed by comparing a pinhole camera (PHC) model with 2 foveation models, that is, a sine curve (SC) model and Advanced Wide Angle Foveated (AdWAF) model...
Group action recognition in soccer videos is a challenging problem due to the difficulties of group action representation and camera motion estimation. This paper presents a novel approach for recognizing group action with a moving camera. In our approach, ego-motion is estimated by the Kanade-Lucas-Tomasi feature sets on successive frames. The optical flow is then computed on compensated frames....
An accurate real-time motion sensor implemented in an FPGA is introduced in this paper. This sensor applies an optical flow algorithm based on ridge regression to solve the collinear problem existing in traditional least squares methods. It additionally applies extensive temporal smoothing of the image sequence derivatives to improve the accuracy of its optical flow estimates. Implemented on a customized...
Cylindrical panoramic mosaics can be created by aligning and stitching images from a series, captured by a camera rotating around its optical center. The transformation between two images must then be found. Existing methods compute a global transformation for the whole image starting from pixels in the overlapping region. This global transformation, due to local distortions often results in ghost...
There is deviation between perceived depth and theoretical depth of virtual object in stereoscopic virtual environment. This paper analyzes its possible causes with optical geometry. In addition, a correcting method performed by setting synthetic viewpoint dynamically is proposed. Experimental results show that this method can reduce the depth deviation to less than 10 millimeter, meeting the requirements...
In this paper, we present a method for tracking and retexturing of garments that exploits the entire image information using the optical flow constraint instead of working with distinct features. In a hierarchical framework we refine the motion model with every level. The motion model is used to regularize the optical flow field such that finding the best transformation amounts in minimizing an error...
This paper proposes a calibration method as well as a computational algorithm to integrate the data of multiple optical flow sensors for 2-dimensional trajectory measurement. Optical flow sensors offer a different kind of odometer as compared with the wheel encoder. Using multiple sensors, it is possible to reduce the effect of measurement uncertainties. Since all sensors are mounted on a rigid body,...
In this paper, we aim to support the scheme that visual cognition is organized by natural neural networks based on experiences. In this scheme the networks learn correlation between temporal variation of visual stimulation and self-motion to organize visual cognition. We propose a neural network that detects temporal variations of visual stimulation and combine them with corresponding self-motion...
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