title: Sign ambiguity in speckle metrology.
abstract: We comment on the propagation of the sign ambiguity produced in the Burch experiment when out-of-plane movements are measured by use of several points of view. The existence of this problem in photogrammetry is also considered.
authors.forename: M
authors.initials: M
authors.lastname: Trivi
authors.forename: H
authors.initials: H
authors.lastname: Rabal