Topographic approaches are often used in the framework of texture characterization. More particularly, level curves proved to be interesting features to describe textures containing elongated patterns. Here, we provide an algorithm for level curve tracking based on a step by step propagation of a level set from a pixel to its neighbors. Textural feature extraction is then considered; orientation and pattern length measurement techniques are proposed. Pattern length retrieval is then exercised on composite material images taken from transmission electron microscopy.