Optimized Data Representation for Interactive Multiview Navigation

Abstract

Abstract-In contrary to traditional media streaming services where a unique media content is delivered to different users, interactive multiview navigation applications enable users to choose their own viewpoints and freely navigate in a 3-D scene. The interactivity brings new challenges in addition to the classical rate-distortion trade-off, which considers only the compression performance and viewing quality. On the one hand, interactivity necessitates sufficient viewpoints for richer navigation; on the other hand, it requires to provide low bandwidth and delay costs for smooth navigation during view transitions. In this paper, we formally describe the novel trade-offs posed by the navigation interactivity and classical rate-distortion criterion. Based on an original formulation, we look for the optimal design of the data representation by introducing novel rate and distortion models and practical solving algorithms. Experiments show that the proposed data representation method outperforms the baseline solution by providing lower resource consumptions and higher visual quality in all navigation configurations, which certainly confirms the potential of the proposed data representation in practical interactive navigation systems.

Optimal Reference Selection for Random Access in Predictive Coding Schemes

“…We also compare our approach to a more sophisticated technique [12] that consists in optimizing the partitioning of the video set. The difference between partitioning and reference frame positioning as proposed in this paper is that partitioning cut the video into several segments of optimized size, and at the transmission, it is considered that the whole segment is transmitted.…”

“…Note that these segments are generally coded with a PC scheme as considered here, which implies that if there are not useful, the transmission of the last frames of a segment could be avoided. To evaluate the benefits of taking into account this partial transmission in the optimization as we propose in this paper, we optimize the reference frame positioning using [12] and our method and we compare the rate-distortion performance. Results are shown in Tab III.…”

“…Optimal positioning of references was investigated in the context of tiling for omnidirectional visual content. In this context, the request now concern tiles, where a tile is a subpart of the onmidirectional image and can be seen as a view in multiview coding [12], [13], [25]. Put in our model, [12], [13], [25] have an additional constraint compared to our work, that is that if the request ends between two references, then the whole segment, from previous reference to next reference, is transmitted to the user.…”

“…Besides, the above works optimize some specific parameters, that are segment size in [12], resolution at which tiles are transmitted in [13], and segment prediction method in [25]. Therefore, these methods do not allow to completely address the tradeoff between RA and compression efficiency.…”

“…First, we consider a naive approach, in which sources with high predictive encoding cost are chosen to be a reference. Second, we incorporate the tiling constraint of [12], [13], [25] into our method, and derive the corresponding optimal solution. Experimental results are compared in terms of BD-rates for the video coding application, and in terms of rate-saving for the other two applications.…”