Axonometric & Oblique Projection With Example

Axonometric & Oblique Projection with example

Sr Dr Md Azree Othuman Mydinazree@usm.my

www.hbp.usm.my/azree

Pictorial Sketching

ObjectivesBe able to explain the difference between anaxonometric projection and an obliqueprojection.

Be able to explain the difference between anisometric projection and an isometricdrawing/sketch.

Be able to create an isometric and obliquesketches from an actual object and multiviewdrawing.

Axonometric& ObliqueProjection

Axonometric Projection

AB

CD

Parallel & normalto picture plane

Lineof

sightA

B

CD

Axonometric ProjectionType of axonometric drawing

a

b c2. Dimetric Two angles are equal.

b

a

c3. Trimetric None of angles are equal.

a

b c1. Isometric All angles are equal.

AB

CDA

B

C

D

Axonometric axis

Axonometric axis

Axonometric axis

A

BC

D

Lineof

sight

Parallel & obliqueto picture plane

Oblique Projection

A

D

C

B

Oblique Projection

A

D

C

B

B

C D

A

Oblique drawing angle

30o45o 60o

Type of Oblique drawing

45o 45o

1) Cavalier 2) Cabinet

Fullscale Half

scale

Isometric Projection& Isometric drawing

Rotate 45about vertical axis

Tilt forward (35o16’)

Isometric Projection

All edges foreshortenabout 0.8 time.

Isometric DrawingIsometric drawing is a drawing drawn on an isometricaxes using full scale.

Isometric projection(True projection)

Isometric drawing(Full scale)

Forshorten

Full scale

Positions of Isometric AxesIsometric axes can be arbitrarily positioned to create different views of a single object.

Regularisometric

Reverse axisisometric

Long axisisometric

View point is lookingdown on the top ofthe object.

View point is lookingup on the bottom ofthe object.

View point is lookingfrom the right (or left)of the object.

Distance in Isometric Drawing

Isometric line is the line that run parallel to any of the isometric axes.

Isometric axes

True-length distances are shown alongisometric lines.

Nonisometric lines

IsometricSketching

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.

1. Place the object in the position which its shape and features are clearly seen.

Sketch from an actual object

STEPS

1. Positioning object.

2. Select isometric axis.

3. Sketch enclosing box.

4. Add details.

5. Darken visible lines.

Sketch from an actual object

1. Positioning object.

2. Select isometric axis.

3. Sketch enclosingbox.

4. Add details.

Note In isometric sketch/drawing), hidden lines are omittedunless they are absolutely necessary to completelydescribe the object.

Sketch from an actual objectSTEPS

5. Darken visible lines.

1. Interprete the meaning of lines/areas in multiview drawing.

2. Locate the lines or surfaces relative to isometric axis.

Sketch from multiview drawing

Front View

Top View

Side View

Example 1 : Object has only normal surfaces

Bottom View

Bottom

FrontSide

SideFront

Top

Regular

Reverse

WD

H

H

DW

Example 2 : Object has inclined surfaces

W

H

D

y

x Front View

y

x

Nonisometric line

Nonisometric line

A

A x

y

x

xB

B

AB

C

C

C

x

y

Example 3 : Object has inclined surfaces

A

A

B

B

C D

ED

EF

F

x

y

Front View

Regular

C

Example 4

Reverse

Circle & Arc in IsometricIn isometric drawing, a circle appears as an ellipse.

2. Construct an isometric square.

3. Sketch arcs that connect thetangent points.

Sketching Steps

1. Locate the centre of an ellipse.

Circle & Arc in Isometric

3. Construct a perpendicularbisector from each tangent point.

4. Locate the four centres.

5. Draw the arcs with these centresand tangent to isometric square.

Sketching Steps

Four-centre method is usually used when drawn an isometric ellipse with drawing instrument.

2. Construct an isometric square.

1. Locate the centre of an ellipse.

Example 5

Irregular Curve in Isometric

1. Construct points along thecurve in multiview drawing.

2. Locate these points in theisometric view.

3. Sketch the connecting lines.

Steps

ObliqueSketching

Object Orientation GuidelinesPlace complex features (arc, hole, irregular shapesurface parallel to frontal plane.

Object Orientation GuidelinesThe longest dimension of an object should beparallel to the frontal plane.

GOOD

WORSE

GOOD

WORSE

Object Orientation Guidelines

Which orientation is better ?

D

45

ESTIMATE DEPTH ESTIMATE LINES

Sketch from actual object

Sketch from multiview drawing

Sketch from multiview drawing

AB

C

D

E

Sketch from multiview drawing

AB

C

D

E

Sketch from multiview drawing

AB

D

E

C

Sketch from multiview drawing

AB

D

E

C

Sketch from multiview drawing