This document covers the principles and techniques of pictorial drawings in mechanical and industrial engineering, focusing on their differences from multiview drawings. It explains various types of projections, including isometric, dimetric, trimetric, and oblique projections, along with methods for sketching objects from actual items and multiview drawings. Additionally, it discusses the representations of circles and ellipses in these drawings and provides guidelines for effectively presenting complex shapes.

1. Addis Ababa University
Addis Ababa Institute of Technology
School of Mechanical & Industrial Engineering
By Tadele Libay
Chapter 4
Pictorial drawings

2. Course objective
AAiT School of Mechanical and Industrial Engineering - SMiE
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At the end of this chapter students are;
 able to explain the difference between an axonometric and an oblique
projection.
 able to explain the difference between an isometric projection and an
isometric drawing/sketch.
 able to create an isometric and oblique sketches from an actual object
and multiview drawing.

3. Pictorial drawing
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• A pictorial drawing is a method of producing a three-dimensional object
from a two-dimensional view, that shows the three main faces indicating
the height, width and depth simultaneously. It is an essential part of the
graphic language.
 Differences between multiview and pictorial drawings
Multiview Drawing Pictorial Drawing
It represents exact shape of an object. It represents overview of an object.
It uses two or more views of an object on different
picture plane.
It represents several views of an object at once on a
single picture plane.
It uses hidden line to represent the hidden parts of an
object.
It rarely uses hidden line when necessary.
It gives detail dimensions of a complex object. It gives overall dimensions of a complex object.
It needs prior knowledge of technical drawing to
understand.
It can be easily understood using common sense.
It is used for manufacturing, construction, production,
and the like.
It is used for promotion, marketing and selling,
business transaction, and the like.

4. Pictorial drawing
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Pictorial Projection
Axonometric Oblique Central/Perspective
Isometric
Dimetric
Trimetric
Cavalier
Cabinet
General
One Point
Two Point
Three Point

5. Pictorial drawing
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 Axonometric projection is a projected view in which the lines of sight are perpendicular to
the plane of projection, but the three faces of a rectangular object are all inclined to the plane
of projection.
 Isometric projection: The receding lines are drawn at 300 from the horizontal and the others
are vertical. Consider a cubic object, the three principal faces and axes are equally inclined to
the plane of projection.
 Dimetric projection: Two of the principal faces and axes are equally inclined to the plane of
projection.
 Trimetric projection: All three principal faces and axes make different angles with the plane
of projection.
 Oblique projection: the projectors are oblique to the plane of projection but parallel to each
other, and one of the principal face (usually front view) of the object is generally parallel to the
plane of projection. The receding line is drawn at 300, 450 and 600 from the horizontal.
 Cavalier: All lines of an object are drawn in their true length.
 Cabinet: Lines on the receding axis are shortened by half.

6. Pictorial drawing
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 Central/perspective projection is the most
realistic three-dimensional view of all the pictorial
projections, because it portrays the object in a
manner that is most similar to how the human eye
perceives the visual world.
 Horizon: an imaginary horizontal line taken at eye
level.
 Vanishing point (VP): a point on the horizon
where receding lines converge.
 One point: have one vanishing point.
 Two point: have two vanishing point.
 Three point: have three vanishing point.

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A
B
C
D
Parallel & normal
to picture plane
Line
of
sight
A
B
C
D
Axonometric drawing
Pictorial drawing

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Type of axonometric drawing
a
b c
2. Dimetric Two angles are equal.
b
a
c
3. Trimetric None of angles are
equal.
a
b c
1. Isometric All angles are equal.
A
B
C
D
A
B
C
D
Axonometric axis
Axonometric axis
Axonometric axis
Pictorial drawing

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A
B
C
D
Line
of
sight
Parallel & oblique
to picture plane
A
D
C
B
Oblique projection
Pictorial drawing

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0
A
D
C
B
B
C D
A
Oblique drawing angle
30o
45o 60o
Type of Oblique drawing
45o
45o
1) Cavalier 2) Cabinet
Full
scale Half
scale
Pictorial drawing

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Rotate 45
about vertical axis
Tilt forward
(35o
16’)
All edges foreshorten
about 0.8 time.
Isometric projection
Pictorial drawing

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 Isometric drawing is a drawing drawn on an isometric
axes using full scale.
Isometric projection
(True projection)
Isometric drawing
(Full scale)
Forshorten
Full scale
Pictorial drawing

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Isometric axes: can be arbitrarily positioned to create different views of
a single object.
Regular
isometric
Reverse axis
isometric
Long axis
isometric
View point is looking
down on the top of
the object.
View point is looking
up on the bottom of
the object.
View point is looking
from the right (or left)
of the object.
Pictorial drawing

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Distance in isometric drawing:
 True-length distances are shown along isometric lines.
 Isometric line is the line that run parallel to any of the isometric axes.
Isometric axes
Nonisometric lines
Pictorial drawing

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1. Place the object in the position which its shape and features
are clearly seen.
2. Define an isometric axis.
3. Sketching the enclosing box.
4. Estimate the size an and relationship of each details.
5. Darken all visible lines.
Sketch from an actual object
Pictorial drawing

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Sketch from an actual object
STEPS
1. Positioning object.
2. Select isometric axis
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.
Note: In isometric sketch/drawing), hidden
lines are omitted unless they are absolutely
necessary to completely describe the object.
Pictorial drawing

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Sketch from an actual object
STEPS
1. Positioning object.
2. Select isometric axis
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.
Pictorial drawing

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Sketch from an actual object: Oblique
STEPS
1. Positioning object.
2. Select oblique axis
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.
Pictorial drawing

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Sketch from Multiview drawing
 Interpret the meaning of lines/areas in multiview drawing.
 Locate the lines or surfaces relative to isometric axis.
Pictorial drawing

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Example 1: Object has only normal surfaces
Front View
Top View
Side View
Bottom View
Bottom
Front
Side
Side
Front
Top
Regular
Reverse
W
D
H
H
D
W
Pictorial drawing

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Example 2: Object has inclined surfaces
W
H
q
D
y
x Front View
y
x
Nonisometric line
Pictorial drawing

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Example 3: Object has inclined surfaces
Nonisometric line
A
A x
y
x
x
B
B
A
B
C
C
C
x
y
Pictorial drawing

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Example 4:
A
A
B
B
C D
E
D
E
F
F
x
y
Front View
Regular
C
Reverse
Pictorial drawing

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Circles in Pictorial Drawing
Circles in pictorial drawing always become ellipses
except it is parallel to normal plane of oblique
pictorial.
In isometric drawing, the circle always become
ellipse.
In oblique drawing when the circle is parallel to
normal plane, it is drawn as its true shape and
become circle; for other planes other than normal
plane the circle becomes ellipse.

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Circles in Pictorial Drawing

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Circles in Pictorial Drawing
Methods to Draw Ellipse:
There are two method namely, offset method
and four center method.
The offset method can be diagonal approach
and division approach.

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Circles in Pictorial Drawing
Diagonal approach offset method.

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Circles in Pictorial Drawing
The four center method as its name indicates uses four center
to draw an ellipse. It is efficient method.
Steps in Four Center Method:
1. Draw a rhombus using the diameter of a circle.
2. Construct perpendicular bisecting lines from each side of
rhombus.
3. Draw lines from obtuse angle corners to opposite side of
rhombus by intersecting the midpoint.
4. Locate the four centers.
5. Draw the arcs with this centers and tangent to rhombus.

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Pictorial drawing

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Pictorial drawing

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Example 5
Pictorial drawing

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Division approach offset method.
Pictorial drawing

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Arcs are usually sketched by locating their centers and then
boxing in the enclosing rhombus and tangent to the rhombus.
Pictorial drawing

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Irregular curve in isometric
Steps:
1. Construct points along the curve in
multiview drawing.
2. Locate these points in the isometric
view.
3. Sketch the connecting lines.
Pictorial drawing

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Object orientation and guideline
 Place complex features (arc, hole, irregular shape surface parallel to frontal
plane.
Pictorial drawing

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Object orientation and guideline
 The longest dimension of an object should be parallel to the frontal plane.
Pictorial drawing

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Object orientation and guideline
 The longest dimension of an object should be parallel to the frontal plane.
GOOD
WORSE
GOOD
WORSE
Pictorial drawing

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Sketch from an object
D
45
ESTIMATE DEPTH
ESTIMATE LINES
Pictorial drawing

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Sketch from Multiview drawing
Pictorial drawing

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Sketch from Multiview drawing
Pictorial drawing

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Sketch from Multiview drawing
Pictorial drawing

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Sketch from Multiview drawing
A
B
C
D
E
Pictorial drawing

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Sketch from Multiview drawing
A
B
C
D
E
Pictorial drawing

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Sketch from Multiview drawing
A
B
D
E
C
Pictorial drawing

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Sketch from Multiview drawing
A
B
D
E
C
Pictorial drawing

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Hidden Lines in Pictorial Drawing
Pictorial drawing

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Hidden Lines in Pictorial Drawing
Pictorial drawing