Extraction of thin nets in grey-level images using computational differential geometry

Abstract

In this paper, we describe a new approach for extracting thin nets in 2−D grey-level images. The key point is to model thin nets as the crest lines of the image surface. Crest lines are the lines where one of the two principal curvatures is locally extremal. We define these lines using first, second and third derivatives of the image. We compute the image derivatives using recursive filters approximating the Gaussian filter and its derivatives. This paper presents an algorithm to extract thin nets from 2−D images and we apply this method to the extraction of roads in satellite images.