56 research outputs found
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Virtual viewpoint three-dimensional panorama
Conventional panoramic images are known to provide for an enhanced field of view in which the scene
always has a fixed appearance. The idea presented in this paper focuses on the use of the concept of virtual
viewpoint creation to generate different panoramic images of the same scene with three-dimensional
component. Three-dimensional effect in a resultant panorama is realized by superimposing a stereo-pair of
panoramic images
Disparity map generation based on trapezoidal camera architecture for multiview video
Visual content acquisition is a strategic functional block of any visual system. Despite its wide possibilities,
the arrangement of cameras for the acquisition of good quality visual content for use in multi-view video
remains a huge challenge. This paper presents the mathematical description of trapezoidal camera
architecture and relationships which facilitate the determination of camera position for visual content
acquisition in multi-view video, and depth map generation. The strong point of Trapezoidal Camera
Architecture is that it allows for adaptive camera topology by which points within the scene, especially the
occluded ones can be optically and geometrically viewed from several different viewpoints either on the
edge of the trapezoid or inside it. The concept of maximum independent set, trapezoid characteristics, and
the fact that the positions of cameras (with the exception of few) differ in their vertical coordinate
description could very well be used to address the issue of occlusion which continues to be a major
problem in computer vision with regards to the generation of depth map
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Robust Adaptive Intra Refresh for Multiview Video
Transmission error propagation in wireless multimedia communication systems has become a recurring
problem. This persistent problem has led to grave consequences on the visual quality of the decoded video.
It is against this backdrop that, we present an adaptive intra refresh (AIR) error-resilient coding tool to
mitigate the effect of transmission error propagation in 3D video communications. This work utilizes
periodic insertion of intra macroblocks in badly error-infected frames temporally as well as related frames
in the multi view video scheme. Our objective is to maximize the transmission efficiency while ensuring the
transmission robustness of the coded bitstream. The selection of periodic macroblocks is based on areas
with high motion above a pre-set threshold. The coding modes of the macroblocks are based on the
distortion expectation due to transmission errors. Extensive simulation results show significant
improvement in both objective and subjective video quality at different intra refresh rates
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Hierarchical video summarisation in reference frame subspace
In this paper, a hierarchical video structure summarization approach using Laplacian Eigenmap is proposed, where a small set of reference frames is selected from the video sequence to form a reference subspace to measure the dissimilarity between two arbitrary frames. In the proposed summarization scheme, the shot-level key frames are first detected from the continuity of inter-frame dissimilarity, and the sub-shot level and scene level representative frames are then summarized by using k-mean clustering. The experiment is carried on both test videos and movies, and the results show that in comparison with a similar approach using latent semantic analysis, the proposed approach using Laplacian Eigenmap can achieve a better recall rate in keyframe detection, and gives an efficient hierarchical summarization at sub shot, shot and scene levels subsequently
Robust multi-view video streaming through adaptive intra refresh video transcoding
A multi-view video (MVV) transcoder has been designed. The objective is to deliver maximum quality 3D video data from the source to the 2D video destination, through a wireless communication channel using all of its available bandwidth. This design makes use of the spatial and view downscaling algorithm. The method involves the reuse of motion information obtained from both the reference frames and views. Consequently, highly compressed MVV is converted into low bit rate single view video that is compliant with H.264/AVC format. Adaptive intra refresh (AIR) error resilience tool is configured to mitigate the error propagation resulting from channel conditions. Experimental results indicate that error resilience plus transcoding performed better than the cascaded technique. Simulation results demonstrated an efficient 3D video streaming service applied to low power mobile devices
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Error resilient video transcoding for robust inter-network communications using GPRS
A novel fully comprehensive mobile video communications
system is proposed in this paper. This system exploits
the useful rate management features of the video transcoders and
combines them with error resilience for transmissions of coded
video streams over general packet radio service (GPRS) mobileaccess
networks. The error-resilient video transcoding operation
takes place at a centralized point, referred to as a video proxy,
which provides the necessary output transmission rates with the
required amount of robustness. With the use of this proposed
algorithm, error resilience can be added to an already compressed
video stream at an intermediate stage at the edge of two or more
different networks through two resilience schemes, namely the
adaptive intra refresh (AIR) and feedback control signaling (FCS)
methods. Both resilience tools impose an output rate increase
which can also be prevented with the proposed novel technique in
this paper. Thus, an error-resilient video transcoding scheme is
presented to give robust video outputs at near target transmission
rates that only require the same number of GPRS timeslots as
the nonresilient schemes. Moreover, an ultimate robustness is
also accomplished with the combination of the two resilience
algorithms at the video proxy. Extensive computer simulations
demonstrate the effectiveness of the proposed system
Multiple description video coding for stereoscopic 3D
In this paper, we propose an MDC schemes for stereoscopic 3D video. In the literature, MDC has previously been applied in 2D video but not so much in 3D video. The proposed algorithm enhances the error resilience of the 3D video using the combination of even and odd frame based MDC while retaining good temporal prediction efficiency for video over error-prone networks. Improvements are made to the original even and odd frame MDC scheme by adding a controllable amount of side information to improve frame interpolation at the decoder. The side information is also sent according to the video sequence motion for further improvement. The performance of the proposed algorithms is evaluated in error free and error prone environments especially for wireless channels. Simulation results show improved performance using the proposed MDC at high error rates compared to the single description coding (SDC) and the original even and odd frame MDC
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3D Holoscopic Imaging for Cultural Heritage Digitalisation
The growing interest in archaeology has enabled the discovery of an immense number of cultural
heritage assets and historical sites. Hence, preservation of CH through digitalisation is becoming a primordial
requirement for many countries as a part of national cultural programs. However, CH digitalisation is still
posing serious challenges such as cost and time-consumption. In this manuscript, 3D holoscopic (H3D)
technology is applied to capture small sized CH assets. The H3D camera utilises micro lens array within a single
aperture lens and typical 2D sensor to acquire 3D information. This technology allows 3D autostereoscopic
visualisation with full motion parallax if convenient Microlens Array (MLA) is used on the display side.
Experimental works have shown easiness and simplicity of H3D acquisition compared to existing technologies.
In fact, H3D capture process took an equal time of shooting a standard 2D image. These advantages qualify
H3D technology to be cost effective and time-saving technology for cultural heritage 3D digitisation
Innovative 3D Depth Map Generation From A Holoscopic 3D Image Based on Graph Cut Technique
Holoscopic 3D imaging is a promising technique for capturing full-colour spatial 3D images using a single aperture holoscopic 3D camera. It mimics flyâs eye technique with a microlens array, which views the scene at a slightly different angle to its adjacent lens that records three-dimensional information onto a two-dimensional surface. This paper proposes a method of depth map generation from a holoscopic 3D image based on graph cut technique. The principal objective of this study is to estimate the depth information presented in a Holoscopic 3D image with high precision. As such, depth map extraction is measured from a single still holoscopic 3D image which consists of multiple viewpoint images. The viewpoints are extracted and utilised for disparity calculation via disparity space image technique and pixels displacement is measured with sub-pixel accuracy to overcome the issue of the narrow baseline between the viewpoint images for stereo matching. In addition, cost aggregation is used to correlate the matching costs within a particular neighbouring region using sum of absolute difference (SAD) combined with gradient-based metric and âwinner takes allâ algorithm is employed to select the minimum elements in the array as optimal disparity value. Finally, the optimal depth map is obtained using graph cut technique. The proposed method extends the utilisation of holoscopic 3D imaging system and enables the expansion of the technology for various applications of autonomous robotics, medical, inspection, AR/VR, security and entertainment where 3D depth sensing and measurement are a concern.NPR
Effects of GOP on multi-view video coding over error prone environments
In this paper, an investigation of the effects of group of pictures on H.264 multiview video coding content over an error prone environment with varying packet loss rates is presented. We analyse the bitrate performance for different GOP and error rates to see the effects on the quality of the reconstructed multiview video. However, by analysing the multiview video content it is possible to identify an optimum GOP size depending on the type of application used. A comparison is demonstrated for the performances between widely known H.264 data partitioning error resilience technique and multi-layer data partitioning technique with different
error rates and GOP in terms of their perceived quality. Our simulation results turned out that Multi-layer data partitioning technique shows a better performance at higher error rates with different GOP. Further experiments in this work have shown the effects of GOP in terms of visual quality and bitrate for different multiview video sequences.The Petroleum Technology Trust Fund (PTDF
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