  There is an emerging sense that the vulnerability of Image Convolutional
Neural Networks (CNN), i.e., sensitivity to image corruptions, perturbations,
and adversarial attacks, is connected with Texture Bias. This relative lack of
Shape Bias is also responsible for poor performance in Domain Generalization
(DG). The inclusion of a role of shape alleviates these vulnerabilities and
some approaches have achieved this by training on negative images, images
endowed with edge maps, or images with conflicting shape and texture
information. This paper advocates an explicit and complete representation of
shape using a classical computer vision approach, namely, representing the
shape content of an image with the shock graph of its contour map. The
resulting graph and its descriptor is a complete representation of contour
content and is classified using recent Graph Neural Network (GNN) methods. The
experimental results on three domain shift datasets, Colored MNIST, PACS, and
VLCS demonstrate that even without using appearance the shape-based approach
exceeds classical Image CNN based methods in domain generalization.
