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1 Chapter 9: Visualization and Graphics Section 9.1 – Why Study Visualization and Graphics?  Visualization and Graphical communication skills are important.

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Presentation on theme: "1 Chapter 9: Visualization and Graphics Section 9.1 – Why Study Visualization and Graphics?  Visualization and Graphical communication skills are important."— Presentation transcript:

1 1 Chapter 9: Visualization and Graphics Section 9.1 – Why Study Visualization and Graphics?  Visualization and Graphical communication skills are important to many engineering disciplines  Some engineering disciplines no longer require drafting classes of any type  The prevalence of computers in the workplace has increased the need for visualization and graphical communication skills

2 2 Chapter 9: Visualization and Graphics Section 9.2 – The Theory of Projection  A method is necessary to depict 3D objects on 2D media like drawings and computer screens  Orthographic Projection incorporates a series of 2D views of an object, yet still completely defines the object

3 3 Chapter 9: Visualization and Graphics Section 9.2 – The Theory of Projection  Projection Theory involves 4 specific components: 1. An object 2. An observer 3. A projection plane (or picture plane) 4. Visual rays

4 4 Chapter 9: Visualization and Graphics Section 9.2 – The Theory of Projection  When the visual rays converge, the projection onto a plane represents a perspective drawing  When the visual rays are parallel (i.e., the observer is very distant), the projection onto a plane represents orthographic projection  The prefix ortho- means perpendicular  Orthographic projection represents views of an object that are all oriented so that the visual rays are perpendicular to the object

5 5 Chapter 9: Visualization and Graphics Section 9.3 – The Glass Box Theory  Suspending an object in a Glass Box, and viewing that object through different faces of that box, is the basis for orthographic projection.

6 6 Chapter 9: Visualization and Graphics Section 9.3 – The Glass Box Theory  If an object’s 3 dimensions are labeled as (1) height, (2) width, and (3) depth, every orthographic view will show exactly 2 of those 3 dimensions:  The front view shows Height and Width only  The right side view shows Height and Depth only  The top view shows Width and Depth only width height depth

7 7 Chapter 9: Visualization and Graphics Section 9.4 – First and Third Angle Projections  The method for how to show and align the different 2D orthographic views leads to 2 main types of projections:  First Angle Projection (used in Europe)  Third Angle Projection (used in the U.S.) Third Angle Projection shown here is used predominantly in the U.S. Third Angle Projection

8 8 Chapter 9: Visualization and Graphics Section 9.5 – The Meaning of Lines  Lines used in orthographic projection can have various meanings, including:  Representing an edge of planar surface  The intersection of two surfaces  The limiting element of a curved surface  In orthographic projection, there are only 3 different ways to depict any planar surface:  As an edge (i.e., in Edge View, or EV)  As a true-size surface, where the line of sight is perpendicular to that surface (i.e., True Size, or TS)  As a foreshortened surface

9 9 Chapter 9: Visualization and Graphics Section 9.6 – Hidden Lines  Orthographic views show all features of an object, including those hidden in a particular view  Hidden lines are drawn as dashed lines  Hidden lines represent features of an object which are hidden in that particular orthographic view  Hidden lines are drawn with a thinner line weight, in addition to being dashed, to distinguish them from thicker, continuous lines used for Visible lines.

10 10 Chapter 9: Visualization and Graphics Section 9.6 – Hidden Lines  Orthographic views show all features of an object, including those hidden in a particular view  Hidden lines are drawn as dashed lines  Hidden lines represent features of an object which are hidden in that particular orthographic view  Hidden lines are drawn with a thinner line weight, in addition to being dashed, to distinguish them from thicker, continuous lines used for Visible lines.

11 11 Chapter 9: Visualization and Graphics Section 9.7 – Cylindrical Features and Radii  Cylindrical features are considered either:  Positivee.g., Outside surface of cylinder  Negativee.g., Holes with circular cross-sections  Centerlines are viewed differently in different orthographic views of a cylinder:  When viewing the circle true size, the center line looks like a cross hair (+)  When viewing the cylinder longitudinally, the center line looks like a single line with a break in the middle

12 12 Chapter 9: Visualization and Graphics Section 9.8 – The Alphabet of Lines and Line Precedence  Line Precedence  Visible lines have highest precedence  Hidden lines have 2 nd highest precedence; if visible and hidden lines coincide, only the visible lines are shown  Center lines have 3 rd highest precedence

13 13 Chapter 9: Visualization and Graphics Section 9.9 – Freehand Sketching  Freehand sketching is very important to the engineer  Quick graphical representations are used frequently to communicate with a variety of others  Proportions are important in freehand sketching  Sketching curved lines represents the greatest challenge in freehand sketching

14 14 Chapter 9: Visualization and Graphics Section 9.10 – Pictorial Sketching  Pictorial sketching: creating a view of the object in which all 3 dimensions are shown  3 Types of Pictorial Sketches: 1. Axonometric (including isometric) 2. Oblique 3. Perspective

15 15 Chapter 9: Visualization and Graphics Section 9.10 – Pictorial Sketching  Isometric Sketches: all 3 dimensions are drawn parallel to each other  Oblique Sketches: The width and height dimensions are drawn perpendicular to each other; the depth dimension is drawn receding at some angle. Depth dimensions are parallel.  Perspective Sketches: At least one dimension has lines which converge on a vanishing point. This is the most realistic looking of all pictorial sketches, yet typically the most time consuming. 

16 16 Chapter 9: Visualization and Graphics Section 9.11 – Visualization  Three Types of Surfaces are used to create a three-dimensional object: 1. Principal surfaces 2. Inclined surfaces 3. Oblique surfaces

17 17 Chapter 9: Visualization and Graphics Section 9.12 – Scales and Measuring  A Scaled Drawing means that there is a constant ratio between the length of a feature on a drawing, and the true length of what it represents  A Scale can represent both (a) a numeric ratio and (b) the tool used to draw and measure features.  Types of scales include:  Engineer’s Scale  Architect’s Scale  Metric Scale

18 18 Chapter 9: Visualization and Graphics Section 9.13 – Coordinate Systems and 3D Space  Computer-Aided-Drafting, or CAD, has been common prevalent in many areas of engineering  2D CAD drawings rely on knowledge of x-y Cartesian coordinate systems  3D CAD drawings rely on knowledge of x-y-z coordinate systems


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