In instances where the template may not provide a direct match, it may be useful to implement the use of eigenspaces - templates that detail the matching object under a number of different conditions, such as varying perspectives, illuminations, color contrasts, or acceptable matching object "poses" [REF].
It is also possible for the matching image to be obscured, or occluded by an object; in these cases, it is unreasonable to provide a multitude of templates to cover each possible occlusion.