Modeling Surface Appearance from a Single Photograph using Self-augmented Convolutional Neural Networks

ACM Transactions on Graphics |

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We present a convolutional neural network (CNN) based solution for
modeling physically plausible spatially varying surface
reflectance functions (SVBRDF) from a single photograph of a
planar material sample under unknown natural
illumination. Gathering a sufficiently large set of labeled
training pairs consisting of photographs of SVBRDF samples and
corresponding reflectance parameters, is a difficult and arduous
process. To reduce the amount of required labeled training data,
we propose to leverage the appearance information embedded in
unlabeled images of spatially varying materials to self-augment
the training process. Starting from a coarse network obtained from
a small set of labeled training pairs, we estimate provisional
model parameters for each unlabeled training exemplar. Given this
provisional reflectance estimate, we then synthesize a novel
temporary labeled training pair by rendering the exact
corresponding image under a new lighting condition. After refining
the network using these additional training samples, we
re-estimate the provisional model parameters for the unlabeled
data and repeat the self-augmentation process until convergence.
We demonstrate the efficacy of the proposed network structure on
spatially varying wood, metal, and plastics, as well as thoroughly
validate the effectiveness of the self-augmentation training
process.