Detection of moving objects for aerial surveillance of arbitrary terrain

[no abstract

Analysis of coding tools and improvement of text readability for screen content

Abstract—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. Remote desktop appli-cations for example often include text parts. As a consequence, these content types contain sharp edges or high frequencies, which are considered less important in natural video and are therefore treated less carefully. The frequent result is an increased occurrence of artefacts or the loss of information that is actually important to the user. This paper gives an analysis of such artificially created video sequences, evaluates the performance of current coding tools for this type of content and proposes a simple, yet effective way to maintain readability of text within video material using only well considered encoder control and without the need of large additional modules. I

A comprehensive video codec comparison

In this paper, we compare the video codecs AV1 (version 1.0.0-2242 from August 2019), HEVC (HM and x265), AVC (x264), the exploration software JEM which is based on HEVC, and the VVC (successor of HEVC) test model VTM (version 4.0 from February 2019) under two fair and balanced configurations: All Intra for the assessment of intra coding and Maximum Coding Efficiency with all codecs being tuned for their best coding efficiency settings. VTM achieves the highest coding efficiency in both configurations, followed by JEM and AV1. The worst coding efficiency is achieved by x264 and x265, even in the placebo preset for highest coding efficiency. AV1 gained a lot in terms of coding efficiency compared to previous versions and now outperforms HM by 24% BD-Rate gains. VTM gains 5% over AV1 in terms of BD-Rates. By reporting separate numbers for JVET and AOM test sequences, it is ensured that no bias in the test sequences exists. When comparing only intra coding tools, it is observed that the complexity increases exponentially for linearly increasing coding efficiency

Keine Angst vor dem Blackout : Ein dezentral organisierter Schwarzstart ist machbar!

[no abstract available

Block size dependent error model for motion compensation

Current video coding standards use block-based motion estimation and compensation algorithms to exploit dependencies between consecutive frames. It is a well-known fact that decreasing the block size reduces the motion-compensated frame difference, and thus reduces the data rate. However, no theoretical evaluations are available to model this relation. This paper derives a model for the prediction error variance of block-based motion compensation algorithms with respect to the block size. It is shown that the variance of the displaced frame difference of a block can be modelled with the pixel position and only three additional parameters. It can be observed that the variance increases almost linearly with the block size. Index Terms — Video coding, motion compensation, block size, block matching, prediction erro

Mesh-based global motion compensation for robust mosaicking and detection of moving objects in aerial surveillance

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 quadrocopter (also called Micro Air Vehicle, MAV) or a helicopter, the motion of the camera directly corresponds to the plane movements. For simplification, only a planar landscape model is used nowadays to describe the global motion of the scene. However, if objects like buildings or mountains are close to the camera, i.e. the MAV is at a low altitude, this simplification is not valid. Therefore we propose a more complex model by introducing a 2D mesh-based motion compensation technique, also known as image warping, to compensate the global motion. We show the benefits if used for mosaick creation by smaller artifacts due to perspective distortions and smaller drift problems. We also improve a moving object detection system to identify moving objects more reliably. Moreover, the proposed method is also more robust in case of lens distortions. 1

Low bit rate roi based video coding for hdtv aerial surveillance video sequences

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 surveillance. Common transmission channels for UAVs are only available with small bandwidths of a few Mbit/s. In this paper we propose a video codec which is able to provide full HDTV (1920 × 1080 pel) resolution with a bit rate of about 1–3 Mbit/s including moving objects (instead of 8– 15 Mbit/s when using the standardized AVC codec). The coding system is based on an AVC video codec which is controlled by ROI detectors. Furthermore we make use of additional Global Motion Compensation (GMC). In a modular concept different Region of Interest (ROI) detectors can be added to adjust the coding system to special operation targets. This paper presents a coding system with two motion-based ROI detectors; one for new area detection (ROI-NA) and another for moving objects (ROI-MO). Our system preserves more details than an AVC coder at the same bit rate of 1.0 Mbit/s for the entire frame. 1

Mesh-based decoder-side motion estimation

Current video coding standards like H.264|AVC perform a block-based motion estimation and compensation at the encoder to exploit temporal dependencies between consecutive frames. Current research proved that motion compensation can also be done profitably at the decoder. In this so-called decoder-side motion estimation (DSME), frames are interpolated at the decoder and inserted into the reference buffer as additional information for prediction. To gather the motion information for compensation, the current approach is based on a block matching algorithm estimating one motion vector for each block of the frame to be interpolated. Therefore, only translational movement is compensated. We evaluate the applicability of a mesh-based motion compensation to DSME which models affine motion in each patch of the mesh and is able to compensate camera zooming or panning, object rotation, or object deformation. I