To facilitate design of non perspective projection by providing a technique of directly performing operation inside three dimensional space through two dimensional projection plane.

First, an object for the operation is displayed on the object displayed in the two dimensional projection drawing. In this stage, the two dimensional projection drawing is generated by projecting a three dimensional model. The three dimensional model is equipped with a plurality of lattice points, and a camera parameter is associated with each of the plurality of the lattice points. Subsequently, the operation for the object of the operation displayed on the two dimensional projection drawing is received. Subsequently, the camera parameter in a moving part in the object for the operation is acquired. Subsequently, the camera parameter for the lattice point is acquired based on the camera parameter in the moving part. Subsequently, the camera parameter corresponding to the peak of the object is acquired by interpolation from the camera parameter for the lattice point. Furthermore, the two dimensional projection drawing for the object acquired using the camera parameter corresponding to the peak of the object is displayed.