Abstract: Coordinates transformation of engineering drawings is the basis process for 3D reconstruction from orthographic views. In this paper, amethod is presented for segmenting engineering drawings into views and establishing the corresponding relations of coordinates between them. Two sets of 2.5D coordinate systems are introduced as intermediates to relate the 2D original drawing system to the 3D space projection coordinates, and a formal technique is developed for constructing transformation matrices between coordinates. Coordinate-constraint-based driving relations are established in addition between the views.