The lifetime of polyester resin samples has been determined with the ASTM D2303 inclined plane tracking test method (IPTTM) for different environmental effects. Most of the external factors have a unique degradation effect, hence the tracking image observed on polyester resin highly depends on these factors. The structure and topography of the tracking patterns generated on the surface of polyester resin have been examined using the fractal dimension model. The accuracy and success of the fractal dimension model can significantly improve the possibility of determining the variety of aging processes that an insulator has been subjected to over a long time period. In order to verify the results, the structures have also been analyzed by using Markov random fields (MRF) and cellular neural networks (CNN). (c) 2004 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.