A system and method locate a central groove in a document such as a book, magazine, or catalog. In one implementation, scores are generated for points in a three-dimensional image that defines a surface of the document. The scores quantify a likelihood that a particular point is in the groove. The groove is then detected based on the scores. For example, lines may be fitted through the points and a value calculated for the lines based on the scores. The line corresponding to the highest calculated value may be selected as the line that defines the groove.