We investigate the challenge of synthesizing dense light fields based on very sparse inputs. With a coarse-to-fine spatial-angular clue modeling, high quality views could be reconstructed that out-performs state-of-the-art methods.

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Densely-sampled light fields (LFs) are beneficial to many applications such as depth inference and post-capture refocusing. However, it is costly and challenging to capture them. In this paper, we propose a learning based algorithm for densely-sampled LF reconstruction, which is capable of generating a denselysampled LF fast and accurately from a sparsely-sampled LF in one forward pass. Our method uses computationally efficient convolutions to deeply characterize the high dimensional spatial-angular clues in a coarse-to-fine manner. Specifically, our end-to-end model first synthesizes a set of intermediate novel subaperture images (SAIs) by exploring the coarse characteristics of the sparselysampled LF input with spatial-angular alternating convolutions. Then, the synthesized intermediate novel SAIs are efficiently refined by further recovering the fine relations from all SAIs via guided residual learning and stride-2 4-D convolutions. Experimental results on extensive real-world and synthetic LF images show that our model can provide more than 3 dB reconstruction quality in average than the state-of-the-art methods while being computationally faster by a factor of 30. Besides, more accurate depth can be inferred from the reconstructed densely-sampled LFs by our method.