A method includes: obtaining designated 3D template for a designated part in a heart; generating 3D annulus data representing an annulus of a heart valve identified as a reference of transformation, from a cross-section image in a plane passing through an axis within the annulus of the identified heart valve in 3D volume data generated from tomographic images; identifying a first point on the annulus of the identified heart valve in the designated 3D template and a second point on the annulus represented by the 3D annulus data; arranging n starting points from the first point on the annulus of the identified heart valve in the designated 3D template and n target points from the second point on the annulus represented by the 3D annulus data; and calculating movement destination coordinates of vertices of polygons relating to the designated 3D template to transform the designated 3D template.