What Is Orthographic Projection?
Orthographic projection (also known as orthogonal projection and analemma[a]) is a method of expressing three-dimensional objects in two dimensions.
It is a type of parallel projection in which all of the projection lines are orthogonal to the projection plane, resulting in an affine transformation of every plane of the scene on the viewing surface.
An orthographic projection’s flipside is an oblique projection, which is a parallel projection with projection lines that are not perpendicular to the projection plane.
The term orthographic is occasionally reserved especially for renderings of things in which the object’s major axes or planes are parallel to the projection plane.
However, in Multiview projection, these are referred to as primary views. Furthermore, axonometric visualizations are those in which the major planes or axes of an item in an orthographic projection are not parallel with the projection plane.
However, these are most commonly referred to as supplementary views. (Axonometric projection may be better stated as synonymous with parallel projection.) Plans, elevations, and sections are examples of sub-types of principal views. Isometric, dimetric, and trimetric projections are examples of auxiliary perspectives.
An object-space telecentric lens is one that provides an orthographic projection.
Types Of Orthographic Projection
The three subtypes of orthographic projection are isometric projection, dimetric projection, and trimetric projection, depending on the exact angle at which the view deviates from the orthogonal.
In axonometric drawing, as in other pictorials, one axis of space is typically depicted as vertical.
Isometric projection– The direction of seeing in isometric projection, the most prevalent kind of axonometric projection in engineering drawing, is such that the three axes of space seem equally foreshortened, with a common angle of 120° between them.
Because the distortion created by foreshortening is uniform, the proportionality between lengths is kept, and the axes share a common scale, making it easier to obtain measurements directly from the drawing.
Another advantage is that 120° angles can be easily formed using only a compass and straightedge.
Dimetric projection- The direction of viewing in dimetric projection is such that two of the three axes of space seem equally foreshortened, and the angle of gazing decides the attendant scale and angles of presentation; the scale of the third direction is chosen separately.
Dimensional approximations are prevalent in dimetric drawings. [Clarification required]
In trimetric projection– the viewing direction is such that all three axes of space look unequally foreshortened.
The scale along each of the three axes and the angles between them are determined independently by the angle of sight.
Dimensional approximations are typical in trimetric drawings, and trimetric perspective is rarely employed in technical drawings.
Orthographic Projection Overview
This is a style of drawing in which Parallel Projection is employed to prepare an item for sketching.
These lines are parallel to the plane. The object is believed to be at infinity in this picture. In such a drawing, the shape of an object is shown in full scale.
A plane is an imaginable surface on which photographs can be prepared. It is then transferred to paper.
This plane is oriented in the direction of the object whose view is to be prepared. In most cases, three perspectives of an object are prepared.
There are three of them: top, front, and side.
- If the plane is kept vertical, it is referred to as the vertical plane.
- If the plane is kept horizontal, it is referred to as the horizontal plane.
- Principal planes are horizontal or vertical planes that are kept perpendicular to each other.
Orthographic Projection Views
In Orthographic Projection, the following views of an item are created.
- Front view.
- Top View
- Side View.
- Bottom View.
- Right side View.
- View from the left side.
In general, the orthographic drawing includes the following three viewpoints.
1. Front View: This view is created by placing the object in front of the camera. This view displays an object’s length and height.
2. Top View: This view is created by gazing at the thing from above. It depicts the object’s length and breadth.
3. Side View: Prepare this view by gazing at the object from the right or left side. It depicts the object’s breadth and height.
A plane is a clean, fictitious, and intangible surface. The drawing created on this fictitious curtain is transferred to the drawing sheet.
For example, if we look at an object through a glass or plastic piece, we will see a picture of the object there. This piece will serve as a plane.
However, this plane is not a material body. It is simply a fictitious curtain that is used to give the contour of a drawing by positioning it in various positions.
This aircraft can be positioned in several ways. On the other hand, the plane in the following positions is referred to as the Principal Plane.
Aside from these positions, the plane will be referred to as an Auxiliary Plane.
1. Frontal Plane
The Frontal plane is a plane that is positioned in front of an object while projections are being drawn.
2. Profile Plane
A plane that is put to the right or left of an item. On this plane, a side perspective of the object is depicted.
3. Horizontal Plane
This is a plane that is positioned upward or downward in the horizontal position of an object. On this plane, a top view of the object is built.
Orthographic Projection Systems.
To create an orthographic drawing, choose one dihedral quadrant and or one octant of a trihedral angle.
As a result, the following four systems are formed:
- The First Angle System.
- The Second Angle System.
- Third Angle System
- Fourth Angle System
In general, the First Angle System and Third Angle System are used. This is due to the fact that the lines of view of the item overlap in the Second and Fourth Angle Systems.
As a result, crisp images cannot be acquired.
1. First Angle System
Views of an object should be taken by placing it in the first quadrant of a dihedral angle or the first octant of a trihedral angle.
A system like this is known as the First Angle System.
The planes are straightened by rotation after taking the front view on the frontal plane, the top view on the horizontal plane, and the side view on the Profile plane.
As a result, the front view takes precedence over the top view, and the side view takes precedence over the front view.
Characteristics of First Angle Projection:
1. The front perspective is always preferred over the top view.
2. The top view is always followed by the front view.
3. The right-side view always comes to the left in the front view.
4. The left side view always comes to the right of the front view.
5. The view is always in the opposite direction of the observer.
6. The object is always in the center of the view and the observer.
2. The Third Angle System.
If the views of an object are captured by placing it in the third quadrant of a dihedral or the third octant of a trihedral arrangement. Third Angle System is the name given to such a system.
Front views form on the frontal plane, top views form on the horizontal plane, and side views form on the profile plane. After taking the views, the planes are rotated to straighten them out.
As a result, the top view is formed by the side of the front view, while the side view is formed by the side of the front view.
Third-Angle Projection Characteristics:
1. The Top view always takes precedence over the Front view.
2. The front view is always below the top view.
3. The right-side view always appears to the right of the front view.
4. The left side view always appears to the left of the front view.
5. The perspective is always established to the observer’s side.
6. The view is always in the midway of the object and the observer.
Orthographic Projection Drawing
Different planes are positioned in a specific order while drawing Orthographic Projection. Then, via each plane, a specific view is drawn. In each of the two Methods, a plane is positioned.
1. The dihedral angle
Two primary planes are kept perpendicular to each other in this manner. One of these planes is called the frontal plane, while the other is called the horizontal plane.
This method yields four right angles, which are referred to as Dihedral Angles.
Each right angle is referred to as a quadrant. To take orthographic projection, the object is placed at either of these right angles.
The frontal plane is used for the frontal view, and the horizontal plane is used for the top perspective. Side views are captured using a profile plane. This plane is held perpendicular to the other two planes’ ends.
2. The trihedral angle
In this procedure, the three Principal planes are taken perpendicular to one another, resulting in eight right angles.
As a result, these are known as trihedral angles.
Each right angle is referred to as an Octant. To take orthographic projection, an item is positioned at either of these right angles.
The frontal plane is used for the frontal view, and the horizontal plane is used for the top perspective. Side views are captured using a profile plane.
In Multiview projection, up to six images of an object are formed, known as primary views, with each projection plane parallel to one of the object’s coordinate axes.
The views are positioned relative to each other using one of two methods: first-angle or third-angle projection. The appearances of views in each can be thought of as being projected onto planes that form a six-sided box around the object.
Although six different sides can be drawn, three views of a drawing usually provide enough information to create a three-dimensional object. These viewpoints are known as the front view, top view, and end view.
These views are also known as a plan, elevation, or section. An auxiliary view is one in which multiple sides of an object are visible in the same image and the plane or axis of the object depicted is not parallel to the projection plane.
As a result, in Multiview projection, isometric, dimetric, and trimetric projections would be considered auxiliary views. One axis of space is frequently shown as vertical in Multiview projection.
An orthographic projection map is a cartographic map projection. The orthographic projection, like the stereographic and gnomonic projections, is a perspective (or azimuthal) projection in which the sphere is projected onto a tangent plane or secant plane.
The orthographic projection’s point of view is infinitely far away. It represents a hemisphere of the planet as seen from space, with the horizon forming a large circle. Shapes and areas are distorted, especially around the edges.
The orthographic projection has been used in cartography since antiquity, and its history is widely documented. In the second century BC, Hipparchus employed the projection to establish the locations of star-rise and star-set.
Marcus Vitruvius Pollio, a Roman engineer, used the projection to build sundials and calculate sun positions around 14 BC.
The first known maps using the projection are woodcut drawings of terrestrial globes from 1509 (anonymous), 1533 and 1551 (Johannes Schöner), and 1524 and 1551 (Johannes Schöner) (Apian).
Orthographic Projection Faqs
What is an example of an orthographic drawing?
An orthographic drawing is a two-dimensional representation of a three-dimensional object. It is also referred to as an orthographic projection. In this image, for example, you can see the front, top, and side views of an airplane.
What are the 3 common view of orthographic projection?
An orthographic projection is a method of expressing a three-dimensional object by employing many two-dimensional perspectives of the thing.
Multiviews are another name for orthographic drawings. The top, front, and right side are the most regularly used views.
What are the types of orthographic projections?
The two most common styles of orthographic drawing, commonly known as ‘working drawings,’ are first angle projections and third angle projections. The position of the plan, front, and side views differs between first and third angle projection.
What are the 6 orthographic views?
When the object’s surfaces are parallel to the sides of the box, the six sides of the box become projection planes, displaying the six views – front, top, left, right, bottom, and rear.
Is isometric an orthographic?
The isometric projection is one type of orthographic projection. (In an orthographic projection, any point in the object is mapped onto the drawing by lowering a perpendicular from that point to the plane of the drawing.)
Where is orthographic projection used?
They are used to depict an object from every angle in order to help producers plan manufacturing.
Beginning with a front view of a product, construction lines highlight where areas combine and are used to design a side and plan (top) view, ensuring that the drawing is accurate from all angles.
What is orthographic projection used for?
The orthographic projection is an azimuthal perspective projection that projects the Earth’s surface from an infinite distance to a plane.
Because it creates the illusion of a three-dimensional globe, it is frequently used as an inset map or for graphic views of the Earth from space.
What are the 3 planes of projection?
The vertical, horizontal, and profile planes are the three primary (or fundamental) projection planes. The angles produced between the horizontal and vertical planes are known as the first, second, third, and fourth angles.
What is Cabinet oblique drawing?
Cabinet oblique projection is another 3D drawing technique that is best suited for cabinet and furniture drawings. In cabinet oblique drawing, we start with the front face of an object and draw the sides, or depths, at 45 degrees.
This correction is used to ensure that the shape or furniture does not appear too lengthy or deep.
How many orthographic projections are there?
Isometric projection, dimetric projection, and trimetric projection are three subtypes of orthographic projection based on the exact angle at which the view deviates from the orthogonal.
What is orthographic first angle projection with examples?
Except for the United States, one of the methods used for orthographic projection drawings is first angle projection, which is approved internationally. The item is put in the first quadrant, in front of the vertical plane and above the horizontal plane, in this projection method.
What is the difference between orthographic and oblique projection?
Another way to look at it is that in an orthographic projection, the projector lines intersect the plane being projected on at a perpendicular angle (thus, they are orthogonal, hence the projection’s name), whereas in an oblique projection, the projector lines form oblique angles (non-right angles) with the projection.
How can you relate orthographic drawing in your everyday life?
Orthographic drawings are frequently used in the design and construction industries to express measurements and shape. Floor plans are often used by real estate agents and realtors to show prospective purchasers the layout and square footage of buildings.