A two-dimensional data generator and a 2D display controller display a two-dimensional plane image based on three-dimensional data read by a three-dimensional data reading unit. A texture amount calculator calculates a texture amount used in rendering a three-dimensional image based on the three-dimensional data at each of a plurality of viewpoints set in the two-dimensional plane. A texture amount exceeding position display controller clearly displays a viewpoint where the calculated texture data amount exceeds a predetermined value in the two-dimensional plane. A texture amount adjusting unit adjusts the data amount of a desired texture.