This paper introduces a methodology for tracking displacements in canvas paintings exposed to relative humidity changes. Displacements are measured by means of the 3D digital image correlation method that is followed by a postprocessing of displacement data, which allows the separation of local displacements from global displacement maps. The applicability of this methodology is tested on measurements of a model painting on canvas with introduced defects causing local inhomogeneity. The method allows the evaluation of conservation methods used for repairing canvas supports.