For the purpose of numerical analysis of threedimensional compressible steady flow around an airplane, it is necessary to find quantitatively local positions of an out surface of the airplane and local directions of the surface in a rectangular computational grid system in physical space. The out surface of airplane is made up of many elements of small triangular planes. The local positions of the out surface in the grid system are determined by local intersections of axes of the grid with these triangular planes. Directions of the triangular planes are substituted for the local directions of the out surfaces. Using these results, views of the out surface of airplane are drawn in sheets of paper.