1. A processing-target image generation device that generates a processing-target image which is an object to be subjected to an image conversion process for acquiring an output image based on an input image taken by an image-taking part, the processing-target image generation device comprising: a coordinates correspondence part configured to cause input coordinates, spatial coordinates, and projection coordinates to correspond to each other, the input coordinates being on an input image plane on which said input image is located, the spatial coordinates being on a space model on which said input image is projected, the projection coordinates being on a processing-target image plane on which said processing-target image is positioned and the image projected on said space model is re-projected, wherein said coordinate correspondence part causes said spatial coordinates on said space model to correspond to said projection coordinates on said processing-target image plane so that lines connecting a plurality of coordinates positions on said processing-target image plane and a plurality of coordinates positions on said space model corresponding to the plurality of coordinates positions on said processing-target image plane, respectively, are parallel to each other on a plane perpendicular to said processing-target image plane.