Projection Techniques and Applications in Civil Engineering Drawing (PDF)

This comprehensive PDF presentation titled “Projection Techniques and Applications in Civil Engineering Drawing” provides an in-depth guide to the essential projection methods used in civil engineering drawings. Projection is a crucial aspect of technical drawing, allowing engineers to represent three-dimensional objects accurately on two-dimensional surfaces, facilitating design communication and construction planning.

The presentation covers key projection techniques, including orthographic projection for accurate plan and elevation views, isometric projection for three-dimensional visualization, and perspective projection for realistic representation. Each technique is explained with step-by-step examples, diagrams, and illustrations relevant to civil engineering applications, such as structural layouts, site plans, and architectural designs.

Additionally, the document demonstrates the integration of **CAD tools** to improve precision, efficiency, and clarity in creating professional projections. Guidelines on scaling, alignment, and dimensioning ensure that drawings are standardized and easily interpretable by architects, engineers, and construction teams.

Designed for civil engineering students, beginners, and professionals, this PDF serves as an essential educational resource. It enhances understanding of projection principles, improves technical drawing skills, and ensures that civil engineering drawings meet global standards. By following the techniques presented here, learners can produce precise, readable, and standardized projections suitable for academic, project, and professional use.

Download this Projection PDF to strengthen your technical drawing abilities and gain confidence in preparing high-quality civil engineering projections that are accurate, clear, and professionally presented.

1. CE 1152
Engineering Drawing
Lecture-5
SabihaTasnimRifa
Department of Civil Engineering, BAUST

2. Projection
The figure or view formed by joining, in correct sequence, the points at which these
lines meet the plane is called the Projection of the object.

3. Projectors: The lines or rays drawn from the object to the plane are called Projectors
Plane of Projection: The transparent plane on which the projections are drawn is known as
Plane of Projection.
Types of Projection:
1.Pictorial projection
i. Perspective projection
ii. Isometric projection
iii. Oblique projection
2. Orthographic projection

4. Pictorial projection
•Pictorial projection is a method of giving an instant three-dimensional view of an object,
and so it is useful for relaying information to a person not used to reading drawings
prepared in orthographic projection.
•The projection in which the description of the object is completely understood in one
view is known as Pictorial Projection.
•The Pictorial projections have the advantage of conveying an immediate impression of
the general shape and details of the object, but no its true dimensions or sizes.
Note:
Isometric projection gives true shape of the object, while Perspective and Oblique
Projections do not

5. Perspective Projection
If any transparent plane is introduced such that the object is in between the observer and the
plane. The image obtained on the plane/screen is as shown. This is called Perspective View of
the object.
Here straight lines (rays) are drawn from various points on the contour of the object to meet the
transparent plane, thus the object is said to be projected on that plane

6. Isometric Projection
•“Iso” means “equal” and “metric projection” means „a projection to a reduced measure‟.
•An Isometric Projection is one type of pictorial projection in which the three dimensions of a
solid are not only shown in one view, but also their dimension can be scaled from this
drawing.

7. Oblique Projection
•The word “oblique” means “slanting” There are three axes-vertical, horizontal and oblique. The
oblique axis, called receding axis is drawn either at 30º or 45º.Thus an oblique drawing can be
drawn directly without resorting to projection techniques.
•Projectors are parallel to each other but not perpendicular to projection plane.
•An oblique projection shows front and top surfaces that include the three dimensions of height,
width, and depth.
•The front or principal surface of an object (the surface toward the plane of projection) is parallel
to the plane of projection.
•Effective in pictorially representing objects

8. Orthographic Projection
“Ortho‟ means “right-angle‟ and “Ortho-graphic‟ means “right-angled drawing.” When the
projections are perpendicular to the plane on which the projection is obtained, it is known as
Orthographic Projection.
Vertical Plane:
• Extend the rays or projectors further to meet a Vertical (Transparent) Plane (V.P) located behind
the object. Join the points at which the projectors meet the plane, in correct sequence. The resulting
view (FV) is called the Front View of the object which is shown in fig. (b)
• Front view shown only two dimensions of the object i.e. Length (L) and Height (H). It does not
show the breadth (B). Thus one view or projection is insufficient for the complete description of the
object.

9. •Look at the object from the top. The projection of the top surface T is TH. TH is the Top
View of the object. Both T and TH are of exactly the same shape and size.
•Thus TH gives the Length (L) and Breadth (B) of the block but not the Height (H).

14. Lines in Drawing
•Solid Line: Used to show the visible edge
•Broken Line: Used to show the edges that are there but not visible from that particular point (Front,
right, left or top