Shadow moire shows contour lines of an object with respect to a master
grating plane; they result from the interference between the lines of
the master grid and their shadow projected by a point source of light
. In best cases the sensitivity of this procedure is a few tenths of a
millimeter. The introduction of a phase-shifting procedure gives a be
tter resolution, but the problem in practice is how can we shift the p
hase of the interferogram into shadow moire? A complete study is prese
nted showing the influence of different parameters. It is shown that o
nly possibility is available. Some applications to three-dimensional s
hape reconstructions are presented with an accuracy of 0.01 mm, showin
g that the potentiality of shadow moire is greatly improved.