3.3 Anomaly Detection with Generative Models 33 (a) Density distribution. (b) ROC curve. (c) Precision-Recall curve. Figure 3.1: ELBO density distribution, ROC curves, and Precision-Recall curves for anomaly “edge erosion” on 3D-printed products, with a 64-dimensional latent space. 3.3.4 Localising Anomalies with Reconstructions Besides providing density estimation, VAEs give us a means to reconstruct an input image into a similar output image on the learned manifold. Ideally, this means that normal images are reconstructed perfectly, whereas anomalous im-
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