Transcript Chapter 6 Pictorials and Sketching Objectives:  Understand the importance of Freehand Sketching.  Understand the terminology used in Pictorial drawings.  Understand the Basics of the.

Chapter 6
Pictorials and Sketching
Objectives:
 Understand the importance of Freehand
Sketching.
 Understand the terminology used in Pictorial
drawings.
 Understand the Basics of the following
projection Methods: Axnonometric, Oblique and
Perspective.
 Be able to Create Freehand 3D Pictorials.
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Engineering Drawings, Pictorials and Sketching
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Engineering design is a process to create and transform ideas
and concepts into a product definition that meet the desired
objective. The engineering design process typically involves three
stages: (1) Ideation/conceptual design stage: this is the beginning
of a engineering design process, where basic ideas and concepts
take shapes. (2) design development stage: the basic ideas are
elaborated and further developed. During this stage, prototypes
and testing are commonly used to ensure the developed design
meet the desired objective. (3) Refine and finalize design stage:
This stage of the design process is the last stage of the design
process, where the finer details of the design is further refined.
Detailed information of the finalized design are documented to
assure the design is ready for production.
Two types of drawings are generally associated with the three
stages of the engineering process: (1) Freehand Sketches and (2)
Detailed Engineering Drawings.
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Freehand Sketches are generally used in the beginning stages of
a design process: (1) To quickly record designer’s ideas and help
formulating different possibilities, (2) To communicate the
designer’s basic ideas with others and (3) To develop and
elaborate further the designer’s ideas/concepts.
During the initial design stage, an engineer will generally picture
the ideas in his/her head as three-dimensional images. The ability
to think visually, specifically three-dimensional visualization, is
one of the most essential skills for an engineer/designer. And
freehand sketching is considered as one of the most powerful
method to help develop visualization skills.
Detailed engineering drawings are generally created during the
second and third stages of a design process. The detailed
engineering drawings are used to help refine and finalize the
design and also to document the finalized design for production.
Engineering drawings typically require the use of drawing
instruments, from compasses to computers, to bring precision to
the drawings.
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Pictorials
Besides the 2D orthographic views, described in the previous
chapter, there are three main divisions commonly used in
freehand engineering sketches and detailed engineering
drawings: (1) Axonometric, with its divisions into isometric,
dimetric and trimetric; (2) Oblique and (3) Perspective.
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Axonometric Projection
The word Axonometric means “to measure along axes".
Axonometric projection is a special orthographic projection
technique used to generate pictorials. Pictorials show a 2D image
of an object as viewed from a direction that reveals three
directions of space. There are three types of axonometric
projections: isometric projection, dimetric projection, and
trimetric projection. Typically in a axonometric drawing, one axis
is drawn vertically.
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Isometric
Dimetric
Trimetric
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Oblique Projection
Oblique Projection represent a simple technique of keeping the
front face of a object parallel to the projection plane and still
reveals three directions of space. An orthographic projection is
a parallel projection in which the projection lines are
perpendicular to the plane of projection. An oblique projection is
one in which the projection lines are other than perpendicular to
the plane of projection. In an oblique drawing, geometry that are
parallel to the frontal plane of projection are drawn true size and
shape.
Oblique
Projection
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Orthographic
Projection
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Perspective Projection
Perspective Projection adds realism to the three-dimensional
pictorial representation; a perspective drawing represents an
object as it appears to an observer; objects that are closer to the
observer will appear larger to the observer. The key to the
perspective projection is that parallel edges converge to a single
point, known as the vanishing point.
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One-Point
Perspective
Two-Point
Perspective
Three-Point
Perspective
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Isometric Sketching
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Oblique Sketching
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One-point perspective
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Two-point perspective
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