To properly evaluate the performance of 360VR-specific encoding and transmission schemes, and particularly of solutions based on viewport adaptation, it is necessary to consider not only the bandwidth saved, but also the quality of the portion of the scene actually seen by users over time. With this motivation, we propose a robust, yet flexible methodology for fine-grained monitoring of the quality within the viewport along the visualization session. This novel procedure is based on a complete analysis of the geometric relations involved. Moreover, the designed methodology allows for both offline and online usage by using different approximations. In this way, our methodology can be used regardless of the approach considered to properly evaluate the implemented strategy, obtaining a fairer comparison between them.

为了正确评估360VR特定的编码和传输方案的性能，尤其是基于视口适应的解决方案的性能，不仅需要考虑节省的带宽，还必须考虑用户在一段时间内实际看到的场景部分的质量。出于这种动机，我们提出了一种健壮而灵活的方法，用于在可视化会话期间对视口内的质量进行细粒度的监视。这个新颖的程序是基于对所涉及的几何关系的完整分析。而且，所设计的方法可以通过使用不同的近似值来实现离线和在线使用。这样，无论考虑采用哪种方法来正确评估已实施的策略，都可以使用我们的方法，从而在两者之间获得更公平的比较。