1. A correction apparatus for other viewpoint closed surface pixel value, comprising: an acquisition unit for point cloud data, acquiring real spatial positional information for a group of measurement points projectable onto a single viewpoint closed surface being a virtual closed surface centering around a single viewpoint, and point cloud data being pixel value information for real spatial positional information; an acquisition unit for coordinate information on single viewpoint closed surface, acquiring coordinate information on the single viewpoint closed surface, the coordinate information on the closed surface for a group of projection points acquired by projecting the group of measurement points on the single viewpoint closed surface; an acquisition unit for coordinate information on other viewpoint closed surface, acquiring coordinate information on other viewpoint closed surface being a virtual closed surface centering around another viewpoint different from the single viewpoint, the coordinate information on the closed surface for a group of projection points acquired by projecting the group of measurement points on the other viewpoint closed surface; an extraction unit for hidden point, extracting a hidden point on a basis of a relative positional relationship between a projection point on the single viewpoint closed surface for an arbitrary measurement point and a projection point neighboring the projection point on the single viewpoint closed surface for the arbitrary measurement point, a relative positional relationship between a projection point on the other viewpoint closed surface for the arbitrary measurement point and a projection point neighboring the projection point on the other viewpoint closed surface for the arbitrary measurement point, distance from the arbitrary measurement point to the other viewpoint, and distance from the measurement point projected onto the neighboring projection point on the other viewpoint closed surface to the other viewpoint, the hidden point being a measurement point hidden behind a physical surface, where the data cannot be acquired when acquiring the point cloud data by centering around the other viewpoint; and a first correction unit for hidden point pixel value, correcting a pixel value of the projection point on the other viewpoint closed surface for the hidden point extracted by the extraction unit for hidden point by utilizing the distance from the measurement point projected onto the neighboring projection point on the other viewpoint closed surface to another viewpoint position and the pixel value of the measurement point.