  Given a geodesic space (E, d), we show that full ordinal knowledge on the
metric d-i.e. knowledge of the function D d : (w, x, y, z) $\rightarrow$ 1
d(w,x)$\le$d(y,z) , determines uniquely-up to a constant factor-the metric d.
For a subspace En of n points of E, converging in Hausdorff distance to E, we
construct a metric dn on En, based only on the knowledge of D d on En and
establish a sharp upper bound of the Gromov-Hausdorff distance between (En, dn)
and (E, d).
