Sunday Emmanuel

@sundayemmanuel · 25 Nov 2021

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What is orthographic projection

The representation of the image of an object when viewed at a right angle to the plane of projection is referred to as orthographic projection. orthographic "means to draw at right angles. An orthographic view of an object is the outlines of the faces which are directly in front of the viewer.
In orthographic projection, there are three planes of projection and they are similar to the floor of a classroom and the two vertical walls of a corner. These three planes are the vertical plane, the side vertical plane, and the horizontal plane.
The view on the vertical plane is called the elevation, or the front view. The view on the side vertical plane is called the end elevation or side view while the view on the horizontal plane is called the Plan.

Method of projection

There are two methods of orthographic projection. The first one is the first angle projection while the second method is the third angle.

First angle prediction: the first angle is most popular in Europe and the formal USSR. In this type of projection, the object is imagined to be in the first quadrant. ... Again, as the observer is normally supposed to look from the right side of the quadrant to obtain the front view, in this method, the projection plane comes in between the observer and the object.

Third Angle projection: the third angle is a universal practice in the USA. In the UK both methods are in common use. This is where the 3D object is seen to be in the 3rd quadrant. It is positioned below and behind the viewing planes, the planes are transparent, and each view is pulled onto the plane closest to it. The front plane of projection is seen to be between the observer and the object. The common practice in engineering drawings is to allow free choice or either first or third.

In this type of projection, the method of specifying views is by using arrows. We have these instructions to produce the front elevation F, which will show a b c d; produce side elevation S which will show A'AD'D; to produce another side elevation Q which will show B'BC'C' and also produce a plan P which will show A'B'AB. These views are to be well-positioned relative to each other.

Steps to follow in drawing projection

Step 1:-leaving adequate space, draw the horizontal line x-x, on top of it, draw ABCD with AB//XX and take dimension into account. The first attempt is in thin lines and later this is thickened out.

Step 2:-draw horizontal, very thin lines through AB and DC producing these lines to the zone of side S.produce A'AB'D' leaving adequate space

Step 3:-Draw Q to similarly produce B'BC'C'

Step 5:-draw line OZ 45° to horizontal and produce A'D' to meet at D'2 D2

Step 6:-Draw horizontal through D'2 and D2 to produce A'B'BA: I e! P which is the plan, thicken A'B'BA out

Step 7:-put on the sign for first angle projection

Step 8:-put dimensions@Henkjan de Krijger #whatisorthographicprojection #methodofprojection #firstangleprojection #thirdangleprojection