In many autonomous target recognition (ATR) investigations it is necessary (or at least desirable) to develop target detection algorithms which function on partially occluded targets as well as open targets. This task may prove difficult if the developers must provide an algorithm based on parameters which are invariant under open and partially occluded conditions. A simpler approach is to detect the possibility of partial occlusion and apply separate detection thresholds or algorithms in such areas. In a typical battlefield outside densely populated areas, only trees have the ability to obscure vehicles from view. The problem of discriminating tree clutter from other types of clutter in the scene environment as viewed from various sensors is addressed in an effort to signal the conditions under which a partially occluded target detection algorithm should be applied. The discussion that follows defines the desirable characteristics of the tree finder, outlines the problem assumptions and examines various strategies for tree clutter discrimination that will be considered.
"Tree Clutter Identification In Multispectral Imagery", Proc. SPIE 1003, Sensor Fusion: Spatial Reasoning and Scene Interpretation, (5 January 1989); doi: 10.1117/12.948939; https://doi.org/10.1117/12.948939