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For the generation of overview panoramic images from aerial surveillance videos, registered video frames are stitched together. Assuming a planar landscape, feature points can be detected and used to estimate a homography. However, if the features are affected by radial distortion, their mapping depends on their position within the frame and the resulting homography becomes inaccurate. As a result,...
For low bit rate scenarios (video conferencing, aerial surveillance), conventional video coding is unable to meet the small bit rate and high quality requirements. In contrast to that Region of Interest (ROI) coding provides an efficient compression by improving the quality of ROIs at the expense of non-ROIs. We also transmit ROI only, but reconstruct non-ROI from already transmitted content by means...
Low bit rate transmission of HD video captured from UAVs is highly interesting. Assuming a planar surface, areas contained in the current frame but not in the previous frames (New Area) can be reconstructed using Global Motion Compensation (GMC). Aiming at stereo reconstruction from monocular video by using motion parallax, a second view of each image pixel has to be additionally transmitted. Whereas...
Region of Interest (ROI) coding is a common method for data reduction in scenarios where bandwidth is crucial like in aerial video surveillance from Unmanned Aerial Vehicles (UAVs). In order to save bits, non-ROI areas are typically reduced in quality or not transmitted at all and thus, an accurate ROI classification is mandatory. Moving objects (MOs) are often considered as ROIs and consequently...
Low bit rate coding systems for the transmission of high quality aerial surveillance videos captured from UAVs are of high interest. One way to achieve high quality low bit rate video is to assume a planar surface of the earth, which is valid for sequences captured at high flight altitudes. Those systems only transmit the area of the current frame not contained in the previous frames (New Area) and...
Current Moving Object Detectors in airborne Region of Interest (ROI) coding systems for police surveillance applications used on-board of UAVs are often based on Global Motion Estimation (GME) techniques. Since in these scenarios the camera is moving, simple background removal approaches cannot be applied without a Global Motion Compensation (GMC). Common GMC algorithms assume the ground to be planar,...
One main element of modern hybrid video coders consists of motion compensated prediction. It employs spatial or temporal neighborhood to predict the current sample or block of samples, respectively. The quality of motion compensated prediction largely depends on the similarity of the reference picture block used for prediction and the current picture block. In case of varying blur in the scene, e...
A major constraint for mobile surveillance systems (e.g. UAV-mounted) is the limited available bandwidth. Thus, ROI-based video coding, where only important image parts are transmitted with high data rate, seems to be a suitable solution for these applications. The challenging part in these systems is to reliably detect the regions of interest (ROI) and to select the corresponding macroblocks to be...
Current video coding standards perform well for video sequences captured by a real camera. The aperture of the camera's optical system smooths the content and attenuates higher frequencies. New application scenarios, enabled by the growing number of high bit rate internet gateways, however, make it necessary to take a closer look at the efficiency of such standards in handling artificial content....
For aerial surveillance systems two key features are important. First they have to provide as much resolution as possible, while they secondly should make the video available at a ground station as soon as possible. Recently so called Unmanned Aerial Vehicles (UAVs) got in the focus for surveillance operations with operation targets such as environmental and disaster area monitoring as well as military...
Global Motion Compensation is one of the key technologies for aerial image processing e.g. to detect moving objects on the ground or to generate a mosaick image of the observed area. For this task, it is necessary to estimate and compensate the motion of the pixels between the recorded frames evoked by the movement of the camera. As the camera is statically attached to a flying device such as a quadro-copter...
The second generation terrestrial transmission standard DVB-T2 introduces the application of MIMO techniques based on the well-known Alamouti scheme for improved mobile and portable reception. However, no channel models are currently available to estimate the gain of Alamouti coding in these channels. Therefore, this document presents a new approach that uses existing DVB-T networks as channel sounder...
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