Abstract: A method for detecting defects in, and/or geometrical characteristics of, at least one joint or splice of sheet pieces, in a unloaded state, characterised by the following steps: a. subjecting said joint or splice to a non-unidirectional electromagnetic radiation; b. performing a two-dimensional detection of the radiation reflected or refracted by said joint or splice; c. generating output signals corresponding to said two-dimensional detection; d. determining possible defects or the geometrical characteristics of at least part of said joint or splice, by analysing, said output signals.