A processing unit includes an estimating unit for estimating three-dimensional
coordinates at an arbitrary point on an observation image and obtaining the estimation
result and the reliability of the estimation result. A concave and convex datum
line setting unit estimates the reliability of a point on the cut-off datum line
or on an extending line of the cut-off datum line based on the reliability of the
estimation result of the estimating unit, extracts only a point whose reliability
is high and setting both new ends, and sets a concave and convex datum line as
a predetermined datum based on both the new ends. The concave and convex datum
line setting unit sets a concave and convex datum line as a predetermined datum
for processing the cross-section information to create concave and convex information
indicating a relative concave and convex state with respect to the predetermined
datum based on both the set new ends. Accordingly, the reliability of the concave
and convex datum line as the datum of the concave and convex information is improved
and more accurate information on the concave and convex state of a target can be
presented to a user.
