The Orthographic Projection is a kind of representation by which an object is presented by the means of line drawing on a projection plane. The plane is perpendicular to the parallel projection.
The term Orthographic drawing means the representation of the exact shape of an object. It is represented in two or more views in which the objects are seen perpendicular to the objects’ surface.
There are two methods in obtaining views in an orthographic drawing; these are the Natural Method and the Glass Box Method.
By looking in the perpendicular side of the object, the Natural method is used to obtain thenatural image. By placing the planes of projection parallel to the principal faces of the objects, the Glass Box method is used to obtain the image or views of the object.
There are three (3) Planes of projection in an Orthographic Drawing; these are the Frontal Plane, the Horizontal Plane and the Profile plane.
The Frontal Plane is the projection plane that projects the front view of an object. The Horizontal Plane is the projection plane that projects the top view of an object. The Profile Plane is the projection plane that projects the side views of the objects.
The Pictorial Drawing is easy to be read even by those who are not skilled in the works of drafting. This drawing is considered as one of the widely used drawing because it shows several faces of illustrations.
There are three (3) types of pictorial drawing; these are the Axonometric, Oblique, and Perspective drawings.
The axonometric drawing is based upon the rotation principles; these are further classified into three (3) kinds, these are Isometric, Diametric and Trimetric.
The Isometric shows the axis of revolution perpendicular to the horizontal plane. In here, the drawing or the object projects or showstwo faces; the objects front as well as the view in the right side.
The Diametric shows or projects two faces of views; the objects’ top view as well as its left side view.
The Trimetric shows or projects three faces or angles; the top view, the left and the right side view.
In the Oblique drawing, one face of the object is parallel in the plane of projection. Like the isometric drawing, the Oblique drawing also uses three axes. The two of these axes are placed in perpendicular to each; while the third axis is placed in any angle that is convenient to the horizontal.
There are two (2) types of Oblique drawing; these are the Cavalier drawing and the Cabinet drawing.
In the Cavalier drawing, the receding lines usually are at thirty (30) degrees or it is at forty five (45) degrees to the horizontal axis.
In the Cabinet drawing, the object is presented as it appears to a particular position in where the observer positioned relative to the object. This drawing presentation looks like the objects actually appear to the eyes of the viewer.
The Perspective Drawing represents the objects as it would actually appear to the observer from a particular place. This is also another kind of pictorial drawing in which objects are presented as they actually appear to the viewers eyes.
There are different kinds of pictorial drawing; the Parallel or One-Point Perspective, the Angular or Two Point Perspective and the Three Point Perspectives.