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Due to the increased need for security and surveillance, PTZ cameras are now being widely used in many domains. Therefore, it is very important for the applications like video mosaic generation or automatic surveillance that these camera be accurately calibrated. In this paper, we address the problem of parameter refinement for such pan-tilt-zoom (PTZ) cameras. Use of bundle-adjustment for parameter...
We present a novel application where, using only three points from the shadow trajectory of an object, one can accurately determine the geo-location of the camera, up to a longitude ambiguity, and also the date of image acquisition without using any GPS or other special instruments. We refer to this as ldquogeotemporal localizationrdquo. We consider possible cases where ambiguities can be removed...
A calibrated camera is essential for computer vision systems. The prime reason being that such a camera acts as an angle measuring device. Once the camera is calibrated, applications like 3D reconstruction or metrology or other applications requiring real world information from the video sequences can be envisioned. Motivated by this, we address the problem of calibrating multiple cameras, with an...
Often the deployed pan-tilt-zoom (PTZ) cameras undergo a pure pan or pure tilt rotation. This is a degenerate case for most of the PTZ camera calibration methods. That is, under this motion, the estimated camera parameters are not unique. In this regard, we present a novel camera calibration method to estimate five camera parameters from these pure pan/tilt cameras by using only two images. Our solution...
In this paper we show that solar shadow trajectories can be used for a robust camera calibration. Expanding on the previous work on calibration from solar shadows, we relax the condition that the shadow casting object be visible in the image. This enables us to work with shadows of non-vertical objects as well. The important observation that we make in this work is that these shadow trajectories form...
Due to their ease of use and availability, pan-tilt-zoom (PTZ) cameras are everywhere. However, in order to utilize these cameras for a meaningful application, it is necessary that these cameras be calibrated. In this paper, we address the problem of calibrating such a rotating and zooming camera and present a simple yet novel solution. We show that in the case of a general rotation the problem can...
Path modeling for video surveillance is an active area of research. We address the issue of Euclidean path modeling in a single camera for activity monitoring in a multi- camera video surveillance system. The paper proposes (i) a novel linear solution to auto-calibrate any camera observing pedestrians and (ii) to use these calibrated cameras to detect unusual object behavior. During the unsupervised...
We address the issue of Euclidean path modeling in a single camera for activity monitoring in a multi-camera video surveillance system. The paper proposes a novel linear solution to auto-calibrate any camera observing pedestrians and uses these calibrated cameras to detect unusual object behavior. The input trajectories are metric rectified and the input sequences are registered to the satellite imagery...
In order to monitor sufficiently large areas of interest for surveillance or any event detection, we need to look beyond stationary cameras and employ an automatically configurable network of nonoverlapping cameras. These cameras need not have an overlapping field of view and should be allowed to move freely in space. Moreover, features like zooming in/out, readily available in security cameras these...
We present a practical framework for registering a mixed reality (MR) environment of an arbitrary number of agents. Each agent consists of a head mounted display (HMD), which consists of a pair of stereo cameras. Each agent is assumed to be moving freely in 3D space and multiple HMDs need not have a common field of view (FoV). We show that the plane at infinity and a common vertical vanishing point...
We present a novel practical method for self-calibrating a camera which may move freely in space while changing it internal parameters by zooming. We show that point correspondences between a pair of images, and the fundamental matrix computed from these point correspondences, are sufficient to recover the internal parameters of a camera. Unlike other methods, no calibration object with known 3D shape...
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