Projection Theory:-
Projection theory is a way of representing a 3D object into 2D object or media graphically. The act of obtaining the image of an object is termed “projection”. The image obtained by projection is known as a “view”.
Variables of projection theory :-
There are two variables of projection theory.
1) Line of sight (LOS) :-
A line of sight (LOS) is a fictional beam of light between an observer’s eye and
an object. It is an imaginary ray of light btw observer eye and object.
Types:
There are 2 types of LOS:
• Parallel
• Converge
Parallel line of sight (Parallel Projection):
If the distance from the viewer to the objective is unlimited then the projectors (i.e., projection lines) are parallel and the drawing is categorized as a parallel projection involves that the object be placed at infinity and observed from numerous side as on an imaginary line corresponding to the object. Parallel projections are less accurate, but they are at ease to draw.
Representation:
If the distance from the viewer to the objective is limited, then the projectors are not parallel and the drawing is categorized as a perspective projection.
Perspective projection needs that the object be located at a determinate distance and noticed from a single point .Perspective projections imitate what the human eye realizes; yet, perspective drawings are challenging to create.
Representation:
2) Plan of projection :-
A plane of projection (i.e, an image or picture plane) is an imaginary flat plane upon which the image created by the line of sight is projected. The image is produced by connecting the points where the lines of sight pierce the projection plane. In effect, 3-D object is transformed into a 2-D representation, also called projections. The paper or computer screen on which a drawing is created is a plane of projection.
Example:-
Q no. 03 :-
Orthographic first angle of projection
Orthographic Projection is a way of drawing an 3D object from different directions. Usually a front, side and plan view is drawn so that a person looking at the drawing can see all the important sides. Orthographic drawings are useful especially when a design has been developed to a stage whereby it is almost ready to manufacture.There are two ways of drawing in orthographic - First Angle and Third Angle. They differ only in the position of the plan, front and side views. Below is an example of First Angle projection.
Q no. 04 :-
Six principles of view :-
Views that are produced by six mutually perpendicular planes of projection. surfaces of the object positioned so that they are parallel to the sides of the box, six sides of the box become projection planes, showing the six views – front, top, left, right, bottom and rear.
• Front view – the one that shows most structures or appearances.
• Left side view – shows what develops the left side of the object after creating the front view position.
• Right side view – shows what develops the right side of the object after forming the front view position
• Top view – shows what develops the top of the object once the location of the front view is recognized.
• Bottom view – shows what the bottom of the object develops once the position of the front view is recognized.
• Rear view – shows what develops the rear of the object once the place of the front view is established.
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