DETERMINING PATCH PERIMETERS IN RASTER IMAGE-PROCESSING AND GEOGRAPHIC INFORMATION-SYSTEMS

Some authors have determined patch perimeters in raster image processi ng and geographic information systems by summing the number of pixels immediately surrounding the patches. We demonstrate that this method i s inaccurate. When applied to satellite sensor imagery, errors ranged from overestimation of perimeter length by 34.5 per cent to underestim ation by 41.7 per cent. Therefore, we developed a new method that is b oth accurate and relatively simple. This method determines perimeters using a standard 3 by 3 pixel moving window. The method can be used wi th most raster systems and has applications in landscape ecology for c alculating such variables as the fractal dimension and ecotone dimensi ons.