axonometric & oblique projection with example
TRANSCRIPT
Axonometric & Oblique Projection with example
Sr Dr Md Azree Othuman [email protected]
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