Apparatus (20A-C) and a method for determining and correcting a deformation in an article (44). An energy beam (29) such as a laser beam is directed to an area (42AC) to reverse (46, 72, 74) an existing deformation or to control deformation during additive fabrication (86, 88). Two sectionally curved areas of a deformation (50A/50C, 52/54) may be heated simultaneously to flatten a bulge between them. An existing or developing deformation may be determined by surface scanning (40) and/or a deformation may be determined predictively to pro-actively correct and prevent it while building or rebuilding a portion of the article by additive fabrication.