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.
