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In this work, we present an algebraic solution to the classical perspective-3-point (P3P) problem for determining the position and attitude of a camera from observations of three known reference points. In contrast to previous approaches, we first directly determine the cameras attitude by employing the corresponding geometric constraints to formulate a system of trigonometric equations. This is then...
Time-of-flight (TOF) depth cameras provide robust depth inference at low power requirements in a wide variety of consumer and industrial applications. These cameras reconstruct a single depth frame from a given set of infrared (IR) frames captured over a very short exposure period. Operating in this mode the camera essentially forgets all information previously captured - and performs depth inference...
This paper tackles the photometric stereo problem in the presence of inaccurate lighting, obtained either by calibration or by an uncalibrated photometric stereo method. Based on a precise modeling of noise and outliers, a robust variational approach is introduced. It explicitly accounts for self-shadows, and enforces robustness to cast-shadows and specularities by resorting to redescending M-estimators...
Efficient and robust detection of humans has received great attention during the past few decades. This paper presents a two-staged approach for human detection in RGB-D images. As the traditional sliding window-based methods for target localization are often time-consuming, we propose to use the super-pixel method in depth data to efficiently locate the plausible head-top locations in the first stage...
Most visual odometry algorithm for a monocular camera focuses on points, either by feature matching, or direct alignment of pixel intensity, while ignoring a common but important geometry entity: edges. In this paper, we propose an odometry algorithm that combines points and edges to benefit from the advantages of both direct and feature based methods. It works better in texture-less environments...
This paper presents an improvement for error reduction of the cost function for non-linear optimization of extrinsic parameters estimation between single line scan LiDAR and RGB camera. The non-linear optimization utilizes a least square scheme by assigning equal weights to all LiDAR measurement points. With robust regression, we used all LiDAR measurement points and removed RANSAC outlier removal...
In this paper, an image-based visual servoing control law is proposed for a quadrotor unmanned aerial vehicle using an on-board monocular camera and an inertial measurement unit sensor. Based on the perspective projection model, suitable image features are defined on a rotated image plane called virtual image plane, thus a decoupled image feature dynamics is achieved. Then, a translational velocity...
Background subtraction is a typical topic in the domain of video processing. In this paper, we propose to cope with background subtraction for separating moving objects from background even cameras are not fixed via modified Bayesian low-rank analysis. Particularly, the hierarchical Bayesian model is proposed for low-rank estimation where the perspective projection is exploited to compensate the camera...
After thirty years of researching, the photometric stereo technique for 3D shape recovery still does not provide reliable results if it is not constrained into very well-controlled scenarios. In fact, dealing with realistic materials and lightings yields a non-linear bidirectional reflectance distribution function which is primarily difficult to parametrize and then arduous to solve. With the aim...
Egomotion estimation is a fundamental issue in structure from motion and particularly for ADAS systems. Several camera motion estimation methods from a set of variable number of image correspondances were proposed. Seven-point method represent the minimal number of required correspondences to estimate the fundamental matrix, raised special interest for their application in a hypothesize-and-test framework...
In the paper, the vision system for tracking of a center point of color markers with disturbance is presented. The authors have proposed the complementary filter algorithm (CF) as well as Kalman Filter (KF) to estimate a central position of the markers. To compute markers central position from marker area two different methods were used. First one is based on measurement of markers center mass. Second...
A unified detection-tracking-estimation vision navigation system and algorithms framework for position and pose estimation of UAV (unmanned aerial vehicle) is proposed in this paper. The major contribution of this work is a novel cooperative object detection algorithm for robust detection of UAV: the spatial color pattern and temporal flicking pattern of the cooperative markers (groups of LEDs) mounted...
Real-time and reliable localization is a prerequisite for autonomously performing high-level tasks with micro aerial vehicles(MAVs). Nowadays, most existing methods use vision system for 6DoF pose estimation, which can not work in degraded visual environments. This paper presents an onboard 6DoF pose estimation method for an indoor MAV in challenging GPS-denied degraded visual environments by using...
In this paper, we use sliding mode control theory to design a 3D vision based controller that is robust to bounded parametric estimation errors. First, we give a model of an eye-in-hand 6 DOF robotic system, including the Pose Reconstruction Algorithm (PRA) used to estimate the position and orientation of the camera with respcet to the scene. In a second step, we propose a model for the uncertainties...
Digital fundus images are commonly used for computer aided diagnosis of different eye disease such as diabetic retinopathy, glaucoma, age related macular degeneration. One issue with fundus cameras is that they provide fundus image only for a small field of view (FOV). This paper presents a novel method to increase the FOV by stitching different fundus images from same patient. The proposed system...
A new robust lane marking detection algorithm for monocular vision is proposed. It is designed for the urban roads with disturbances and with the weak lane markings. The primary contribution of the paper is that it supplies a robust adaptive method of image segmentation, which employs jointly prior knowledge, statistical information and the special geometrical features of lane markings in the bird's-eye...
People often capture document images from their mobile camera or handheld digital camera. These cameras are handy and can capture partial images of a big document like chart or new paper and text written on wall. Image mosaic king is the process of reconstructing the whole image from its constituent partial overlapped images. If partial images of a document are captured by flatbed scanner then mosaic...
In this paper, we propose a robust curved lane marking detection method by first detecting a straight lane and applying a geometric model of that detected straight lane. In our proposed method, we first detect the straight line and generate 13 candidates of the curved lane by applying a geometric model. We then vote those candidates on the feature image and consider the candidate which acquires the...
Mechatronic systems are usually described by integer-order state equations. Based on these integer-order models, conventional integer-order PID controllers are designed. In this paper, we use a Steward platform (ball and plate system) with different balls to investigate the robustness of the fractional-order controller against the mass changes of the ball. The closed-loop performances of the fractional-order...
In this paper, we proposed a disturbance rejection control method to improve the position keeping accuracy of an underwater robot. Not like a ground robot, the controlling of a floating body is a critical requirement to acquire high quality sensor data from, for examples, a gyro, an underwater optical camera, and an imaging sonar. The proposed controller consists of a model-based robust compensator...
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