Robust to outlier image inpainting for interface detection in primary separation vessel

Abstract

The Primary Separation Vessel (PSV) is integral to the bitumen extraction process in the oil sands industry. Effective control of the interface between the froth and middlings layers is critical for the PSV’s optimal operation. Computer vision techniques can monitor this interface using the images captured from the PSV sight glass. However, image-based models suffer from a lower performance when the image quality is inferior. This is evident in the case of the image data being affected by external degradations. Image inpainting addresses the task of removing unwanted objects and improving the quality of the images. Variational Autoencoder (VAE) can be trained to remove the degradations and restore the image quality. However, in the latent space of a standard VAE which uses a Gaussian distribution for the prior, the input information is spread across all the latent dimensions. This is not suitable particularly in scenarios where the input data consists of a limited number of salient features, without involving complex patterns. This under-regularization of latent space may impact the performance of inpainting when outliers are present in the training data. In this article, a Laplace VAE framework is proposed where the prior is modeled as a Laplace distribution to achieve a better regularization of the latent space and enhance robustness to the outliers in training data. Further, we demonstrate that the Laplace prior promotes sparsity in the latent representations, when there are limited features of interest in the input. This model is used to restore degraded images from a pilot-scale PSV and the interface level is predicted from the restored images using a region-based segmentation method.