pictorial drawings gmed unit 1. pictorial drawings
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Pictorial Drawings
GMED UNIT 1GMED UNIT 1
Pictorial Drawings
15-1 Pictorial Drawings
Types of pictorial drawings
Types of axonometric drawings
Isometric drawings
PhotoDisk
Types of pictorial drawings:
Axonometric projection
Types of pictorial drawings:
Oblique projection
Types of pictorial drawings:
Perspective
A projected view in which the lines of sight are perpendicular to the plane of projection, but in which the three faces of a rectangular object are all inclined to the plane of projection.
Definition:Axonometric projection
PhotoDisk
Types of axonometric projection: Isometric
The three principal faces and axes are equally inclined to the plane of projection
Trimetric All three faces and axes make
different angles with the plane of projection
Dimetric Two of the principal faces and axes
are equally inclined to the plane of projection
SHAPE DESCRIPTION
The AXONOMETRIC projection is a three dimensional representation in which the lines of sight are perpendicular to the plane of projection.
ISOMETRIC DIMETRIC TRIMETRIC
Isometric drawings The object is revolved 45
to the horizontal.
Lines are drawn to true length.
The object is tipped up or down 3516’.
ISOMETRIC PROJECTION
True measurements are made along three major axes, which are:• VERTICAL
• 30 degrees up to the RIGHT
• 30 degrees up to the LEFT
Drawing object to actual measurement
30° 30°
30°
ISOMETRIC PROJECTION
The basic procedure used in drawing isometrics is to use an isometric grid.Next, draw all lines along the three major axes.
ISOMETRIC PROJECTION
When sketching, use isometric grid paper as a guide.
15-2 Curved Surfaces in Isometric
Circles and arcs in isometric drawings
Irregular curves
PhotoDisk
A circle drawn in isometric
has the shape of an ellipse on any of the three faces.
Quick Quiz
Isometric, dimetric, and trimetric are types of what kind of pictorial drawing?
Axonometric projection
15-3 Common Features in Isometric
Isometric sectioning
Drawing conventions: Fillets, rounds, and threads
PhotoDisk
Sections in isometric The section is taken on an isometric
plane. In full section, construction lines
represent the part cut away.
15-4 Oblique Projection
Types of oblique projection
Drawing objects in oblique projection
Inclined surfaces
Oblique projection drawings
The object is placed with one face parallel to the frontal plane.
The other two faces are placed on oblique (receding) planes at a convenient angle.
The three axes are vertical, horizontal, and receding.
Types of oblique projection
Cavalier oblique All lines a drawn in their true length.
Cabinet oblique Lines on the receding axis are shortened
by one-half.
15-5 Common Features in Oblique
Circles and arcs
Sections in oblique
Drawing conventions
Lawrence Lawry
Circles in oblique projection
When possible, the face having circles or arcs should be selected for the front face.
Methods for drawing circles or arcs on an oblique face: The offset
measurement method
In CAD: Use the ellipse command, specifying degree of exposure.
The four-center method
Quick Quiz
What are the two types of oblique projection?
Cavalier and cabinet
15-6 Parallel, or One-Point, Perspective
Perspective projection
Types of perspective drawings
Perspective drawing and sketching
PhotoDisk
Definitions:
Picture plane: The plane of projection
Station point: The position of the observer’s eye
Definitions:
Horizon: An imaginary horizontal line taken at eye level
Vanishing point: A point on the horizon where receding lines converge
Types of perspective drawings Parallel
One vanishing point
Types of perspective drawings Angular
Two vanishing points
Types of perspective drawings Oblique
Three vanishing points
SHAPE DESCRIPTION
There are three types of PERSPECTIVE projections: 1. PARALLEL
Vanishes to one point
VP
SHAPE DESCRIPTION
There are three types of PERSPECTIVE projections: 2. ANGULAR
Vanishes to one point
Vanishes to one point
SHAPE DESCRIPTION
There are three types of PERSPECTIVE projections: 3. OBLIQUE
Vanishes to one point
Vanishes to one point
Vanishes to one point
15-7 Angular, or Two-Point, Perspective
Angular perspective drawing and sketching
Angular perspective in CAD
Grids for angular perspective sketching Exterior
Worm’s-eye view
Bird’s-eye view
Interior
15-8 Solid Modeling
Types of solid modeling
Image generation
Data extraction
Jonnie Miles
Types of solid modeling:
Wire-frame models
Solid models
Surface models
Types of solid models Constructive Solid Geometry (CSG) (15-8-7
to come) Combines shapes using Boolean operations (union, subtraction, and intersection)
Boundary Representation (BREP) Joins surfaces using extrusion or by
revolution
Quick Quiz
What kind of perspective drawing has two vanishing points?
Angular perspective