1. An image generation device that generates an output image including a road image based on plural input images that are captured by plural cameras mounted to a body to be operated, the image generation device comprising: a control part that alternately arranges input image portions of two cameras of the plural cameras that correspond to an overlapping area of image capturing ranges of the two cameras to form a lattice pattern on the output image; wherein the lattice pattern includes as a unit pattern a region that is defined by two circles having a center at a position of a first camera of the two cameras, and two circles having a center at a position of a second camera of the two cameras; the lattice pattern includes as the unit pattern a lattice defined by a circle delineated by a peak of a first wave from a first wave source located at the position of the first camera, a circle delineated by a trough of the first wave, a circle delineated by a peak of a second wave from a second wave source located at the position of the second camera, and a circle delineated by a trough of the second wave; the control part associates coordinates on an output image plane corresponding to the unit pattern that intersects an antinodal line formed by the first wave and the second wave with coordinates on a first input image plane of the first camera; and the control part associates coordinates on the output image plane corresponding to the unit pattern that intersects a nodal line formed by the first wave and the second wave with coordinates on a second input image plane of the second camera.