An example of the present invention is a data processing apparatus including, a saving part configured to save three-dimensional data of a subject, a two-dimensional image display part configured to display three-dimensional data of the subject as a two-dimensional image, a designation part configured to designate coordinate information associated with a specific coordinate point on the two-dimensional image, a specifying part configured to specify, based on the coordinate information designated on the two-dimensional image, coordinate information on the corresponding three-dimensional data, and a calculation part configured to calculate a view angle of the subject on the basis of the coordinate information on the three-dimensional data.