1. A cross-section data generating device comprising: a storage that stores a three-dimensional polygon model including color information; a shape obtaining processor configured or programmed to obtain a shape of an outline of the three-dimensional polygon model at a cross section, which is a plane that intersects the three-dimensional polygon model; and a color information obtaining processor configured or programmed to obtain color information of the outline at the cross section, wherein the color information of the outline includes color information of points and lines of the shape; and the shape of the outline includes points of intersection between the cross section and the three-dimensional polygon model and lines of intersection between the cross section and the three-dimensional polygon model.