Three-dimensional image construction apparatus and three-dimensional image construction method

A three-dimensional image construction method executing:

• displaying, via a display unit, a first three-dimensional image on a predetermined origin surface;
• receiving, via an input unit, an input of a region of interest for a second three-dimensional image, in the first three-dimensional image;
• setting, via a calculation unit, the origin surface as an initial value of the origin of a projection line to construct a second three-dimensional image;
• correcting, via the calculation unit, the origin of the projection line for a pixel in the region of interest based on a depth image corresponding to the first three-dimensional image;
• and
• constructing, via the calculation unit, the second three-dimensional image using the corrected origin of the projection line for the region of interest;
• wherein the calculation unit:
• extracts a first image region based on a depth gradient of the depth image in the region of interest,
• corrects the origin of the projection line for the pixel in the first image region to a direction opposite to a projection direction or the projection direction by a certain distance as the first step of repetitive processing and memorizes the corrected origin of the projection line in a storage unit,
• extracts a second image region based on a depth gradient of the depth image on the basis of the corrected origin of the projection line as the second step of repetitive processing in the first image region,
• determines whether the second image region satisfies end conditions or not as the third step of repetitive processing,
• sets the second image region as the new first image region if the end conditions are not satisfied and repeats the third step from the first step until the end conditions are satisfied, and then
• constructs the second three-dimensional image using the corrected origin of the projection line memorized in the storage unit for the region of the interest if the end conditions are satisfied.