Size-constrained region merging (SCRM): An automated delineation tool for assisted photointerpretation

The manual delineation of vegetation patches or forest stands is a costly and crucial stage in any land-cover mapping project or forest inventory based upon photointerpretation. Recent computer techniques have eased the task of the interpreter; however, a good deal of craftsmanship is still required in the delineation. In an effort to contribute to the automation of this process, we introduce Size-Constrained Region Merging (ScRm), a recently implemented software tool that provides the interpreter with an initial template of the to-be-mapped area that may reduce the manual digitization portion of the interpretation. In essence, SCRM transforms an ortho-rectified aerial or satellite image (single or multi-channel) into a polygon vector layer that resembles the work of a human interpreter, whom with no a priori knowledge of the scene, was given the task of partitioning the image into a number of homogeneous polygons all exceeding a minimum size. We provide background information on SCRM foundations and workflow, and illustrate its application on three different types of satellite images.