Viewport Rendering Algorithm with a Curved Surface for a Wide FOV in 360° Images

Abstract

Omnidirectional visual content has attracted the attention of customers in a variety of applications because it provides viewers with a realistic experience. Among the techniques that are used to construct omnidirectional media, a viewport rendering technique is one of the most important modules. That is because users can perceptually evaluate the quality of the omnidirectional service based on the quality of the viewport picture. To increase the perceptual quality of an omnidirectional service, we propose an efficient algorithm to render the viewport. In this study, we analyzed the distortions in the viewport picture to be the result of sampling. This is because the image data for the unit sphere in the omnidirectional visual system are non-uniformly sampled to provide the viewport picture in the conventional algorithms. We propose an advanced algorithm to construct the viewport picture, in which the viewport plane is constructed using a curved surface, whereas conventional methods use flat square surfaces. The curved surface makes the sampling interval more equally spaced than conventional techniques. The simulation results show that the proposed technique outperforms the conventional algorithms with respect to the objective quality based on the criteria of straightness, conformality, and subjective perceptual quality.

Keywords

• viewport rendering
• omnidirectional media
• immersive media