# The Cube Surface Light Field for Interactive Free-Viewpoint Rendering
## 6 Conclusions  
To overcome the limited viewpoint freedom and poor time performance in free-viewpoint rendering, this paper has proposed a novel method that encodes the whole scene by the cube surface light field and renders the novel views using a single-layer ray casting algorithm. We adopted a texture compression algorithm to make the light field's data amount acceptable for a personal computer and processed the under-sampled light rays using several light field interpolation methods, including the BCI and CBSI. The cube surface light field represents all the light rays that have a significant impact on the scene's appearance, indicating that the DoF of the viewpoints during the rendering can be at arbitrary positions and viewing directions outside the cube surface. Experimental results have demonstrated that the proposed method significantly improves the DoF of rendering compared with traditional 2 PP light field methods. Moreover, results have also proved that our method has the advantages of real-time performance (more than 75 FPS on a moderate computer) and can render arbitrary views interactively while ensuring high image quality.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Viewpoint**} & \multirow{2}{*}{**Index**} & \multicolumn{6}{c}{**Method**} \\ \cline{3-8}  & & **NNI** & **LI** & **BLI** & **BCI** & **CBSI** & **Path Tracing** \\ \hline \multirow{3}{*}{A} & BRISQUE & 39.16 & 38.7 & 38.42 & 37.65 & 37.08 & 30.29 \\  & NIQE & 4.94 & 4.78 & 4.65 & 4.6 & 4.49 & 11.16 \\ \multirow{3}{*}{B} & BRISQUE & 35.76 & 35.66 & 35.28 & 35.58 & 34.74 & 17.91 \\  & NIQE & 4.8 & 4.72 & 4.52 & 4.52 & 4.45 & 10.32 \\ \multirow{3}{*}{C} & BRISQUE & 36.32 & 36.01 & 35.47 & 35.68 & 34.86 & 26.24 \\  & NIQE & 4.92 & 4.74 & 4.52 & 4.55 & 4.43 & 11.06 \\ \hline \hline \end{tabular}
\end{table}
Table 2: The BRISQUE and NIQE evaluations on the novel views rendered by different methods. The green number indicates the best result among the different interpolation methods, and the red number indicates that path tracing method gets better results.  
Figure 10: The comparisons between different interpolation methods and the path tracing rendering using (**a**) SSIM and (**b**) PSNR.  
**Author Contributions:** Conceptualization, X.A. and Y.W.; methodology, X.A. and Y.W.; software, X.A.; validation, X.A. and Y.W.; formal analysis, X.A.; investigation, X.A.; resources, X.A.; data curation, X.A.; writing--original draft preparation, X.A.; writing--review and editing, X.A. and Y.W.; visualization, X.A. and Y.W.; project administration, Y.W.; funding acquisition, Y.W. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by Zhejiang Provincial Science and Technology Program in China under grant number 2021C03137.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.  
**Conflicts of Interest:** The authors declare no conflict of interest.