M onitoring land-cover changes: a com parison of change detection techniques*

Abstract

Six change detection procedures were tested using Landsat Multi- Spectral Scanner (MSS) images for detecting areas of changes in the region of the Te rminos Lagoon, a coastal zone of the State of Campeche, Mexico. The change detection techniques considered were image di erencing, vegetative index di erencing, selective principal components analysis (SPCA), direct multi-date unsupervised classi® cation, post-classi® cation change di erencing and a combina- tion of image enhancement and post-classi® cation comparison. The accuracy of the results obtained by each technique was evaluated by comparison with aerial photographs through Kappa coe cient calculation. Post-classi® cation compar- ison was found to be the most accurate procedure and presented the advantage of indicating the nature of the changes. Poor performances obtained by image enhancement procedures were attributed to the spectral variation due to di er- ences in soil moisture and in vegetation phenology between both scenes.Methods based on classi® cation were found to be less sensitive at these spectral variations and more robust when dealing with data captured at di erent times of the year.