ABSTRACT
This chapter describes non-photorealistic techniques which can be used to aid search interaction techniques. It describes a range of methods for performing sketch-based 3D shape retrieval. The chapter covers traditional approaches as well as some of the recent deep learning approaches to both line detection and shape retrieval. The chapter also considers contour and crease lines, for which the authors can expect to find evidence directly from local features in the model or image. A related topic to line detection is edge detection, which the authors will also cover, since lines drawn by both artists and users sketching for retrieval could represent either lines or edges. Moreover, curvature and the majority of 3D model-based line detection methods are independent of the lighting conditions.
