This paper presents a new method for extracting object edges from range images obtained by a 3D imaging sensor−the SwissRanger SR-3000. In the range image pre-processing stage, the method enhances object edges by using surface normal information; and it employs the Hough Transform to detect straight line features in the Normal-Enhanced Range Image (NERI). Due to the noise in the sensor’s range data, an NERI contains corrupted object surfaces that may result in unwanted edges and greatly encumber the extraction of linear features. To alleviate this problem, a Singular Value Decomposition (SVD) filter is developed to smooth object surfaces but retain edges. The efficacy of the edge extraction method is validated by experiments in various indoor environments.