Podcast
Questions and Answers
What happens to a circular hole in perspective drawing?
What happens to a circular hole in perspective drawing?
- It turns into a square
- It remains circular
- It becomes an ellipse (correct)
- It disappears entirely
A right angle in perspective drawing can appear as an obtuse angle.
A right angle in perspective drawing can appear as an obtuse angle.
True (A)
What are the three dimensions considered in multiview drawing?
What are the three dimensions considered in multiview drawing?
Height, Width, Depth
In multiview drawing, the observer can either revolute the object or __________ around it.
In multiview drawing, the observer can either revolute the object or __________ around it.
Match each view of the object with its corresponding position:
Match each view of the object with its corresponding position:
Which drawing technique requires understanding the relative orientation of views?
Which drawing technique requires understanding the relative orientation of views?
The depth of an object is irrelevant in multiview drawing.
The depth of an object is irrelevant in multiview drawing.
What is the glass box concept in relation to drawing methods?
What is the glass box concept in relation to drawing methods?
What shape should the intersection between hidden lines form?
What shape should the intersection between hidden lines form?
A center line should always start and end with a short dash.
A center line should always start and end with a short dash.
What type of line denotes a visible line in the drawings?
What type of line denotes a visible line in the drawings?
The hidden line should join a visible line, except it extends from a visible line ______.
The hidden line should join a visible line, except it extends from a visible line ______.
In a circular view, where should the short dash of a center line cross?
In a circular view, where should the short dash of a center line cross?
Match the line types with their descriptions:
Match the line types with their descriptions:
For small holes, the center line is presented as a thin continuous line.
For small holes, the center line is presented as a thin continuous line.
What is the minimum gap that should be left when a center line forms a continuation with a visible or a hidden line?
What is the minimum gap that should be left when a center line forms a continuation with a visible or a hidden line?
In a multiview drawing, what happens in the case of intersection?
In a multiview drawing, what happens in the case of intersection?
In a multiview drawing, a tangential relationship indicates that an edge and a line exist.
In a multiview drawing, a tangential relationship indicates that an edge and a line exist.
What are the three types of planes mentioned?
What are the three types of planes mentioned?
When lines coincide in a drawing, the most important line is a _____ line.
When lines coincide in a drawing, the most important line is a _____ line.
Match the following line types with their descriptions.
Match the following line types with their descriptions.
What is the order of precedence for lines in multiview drawings?
What is the order of precedence for lines in multiview drawings?
Modifying an object's features has no effect on its multiview drawing.
Modifying an object's features has no effect on its multiview drawing.
What should you attempt when relating object features to lines in a multiview drawing?
What should you attempt when relating object features to lines in a multiview drawing?
What concept helps in visualizing the projection of an inclined plane?
What concept helps in visualizing the projection of an inclined plane?
An obliqued line maintains its angle during projection.
An obliqued line maintains its angle during projection.
What is the purpose of transferring a depth in drawing?
What is the purpose of transferring a depth in drawing?
The projection of a ______ surface can either tangent or intersect with an adjacent plane.
The projection of a ______ surface can either tangent or intersect with an adjacent plane.
Match the type of projection to its correct description:
Match the type of projection to its correct description:
Which of the following best describes a miter line?
Which of the following best describes a miter line?
In projection drawings, it's essential to provide space between front and side views.
In projection drawings, it's essential to provide space between front and side views.
What do the letters 'BT', 'AT', and 'BR' typically denote in projection drawings?
What do the letters 'BT', 'AT', and 'BR' typically denote in projection drawings?
Which of the following shapes has no edges?
Which of the following shapes has no edges?
All surfaces can only be plane and cannot be curved.
All surfaces can only be plane and cannot be curved.
What is used in multiview drawing to indicate the existence of a hidden edge?
What is used in multiview drawing to indicate the existence of a hidden edge?
A surface is defined as an area that is bounded by edges or _______.
A surface is defined as an area that is bounded by edges or _______.
Match the following shapes with their characteristics:
Match the following shapes with their characteristics:
What is the primary purpose of projection theory in orthographic projection?
What is the primary purpose of projection theory in orthographic projection?
Orthographic projection includes both parallel and oblique lines of sight.
Orthographic projection includes both parallel and oblique lines of sight.
What type of drawing shows a virtual 3D view of an object?
What type of drawing shows a virtual 3D view of an object?
The _____ projection uses parallel lines of sight.
The _____ projection uses parallel lines of sight.
Which of the following are types of projections mentioned in the content?
Which of the following are types of projections mentioned in the content?
Match each type of projection with its characteristic:
Match each type of projection with its characteristic:
A disadvantage of multiview drawing is that it requires training to visualize.
A disadvantage of multiview drawing is that it requires training to visualize.
What are the two primary variables that projection theory is based on?
What are the two primary variables that projection theory is based on?
What is the function of a rib and web in structural design?
What is the function of a rib and web in structural design?
A spoke is the rod that connects the hub to the rim of a wheel.
A spoke is the rod that connects the hub to the rim of a wheel.
What is the definition of a lug in mechanical terms?
What is the definition of a lug in mechanical terms?
In section view representation, omit the section lines on the section view of ______, ______, and ______ if the cutting plane is passed flatwise through.
In section view representation, omit the section lines on the section view of ______, ______, and ______ if the cutting plane is passed flatwise through.
Match the following terms with their corresponding descriptions:
Match the following terms with their corresponding descriptions:
What is an aligned section?
What is an aligned section?
Conventional breaks are used to display long objects in a small scale by removing unimportant long portions.
Conventional breaks are used to display long objects in a small scale by removing unimportant long portions.
What is the recommended practice when cutting through a spoke?
What is the recommended practice when cutting through a spoke?
Flashcards
Edge
Edge
A boundary line where two surfaces meet. Think of it as the sharp edge of a box or the seam between two pieces of paper.
Surface
Surface
The flat or curved area that makes up the outside of an object. Imagine the smooth face of a cube or the curved exterior of a ball.
Surface limit
Surface limit
A line marking the end of a surface. It's like the border of your drawing.
Normal Line
Normal Line
A line that is perpendicular to a plane and represents the direction an object is facing.
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Normal Plane
Normal Plane
A flat surface that is perpendicular to a line of sight. Think of it as a transparent wall.
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Multiview drawing
Multiview drawing
A type of drawing where an object is viewed from multiple directions, creating related images that show its complete form.
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Projection line
Projection line
The line that represents the intersection of a plane of projection and the object.
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Depth in Multiview drawing
Depth in Multiview drawing
A visual representation of an object's height, width, and depth, where depth is shown by angles and perspectives.
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Moving observer method
Moving observer method
A method of creating multiview drawings by moving the observer around a stationary object.
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Revolving object method
Revolving object method
A method of creating multiview drawings by rotating the object while the observer remains in a fixed position.
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Orthographic Projection
Orthographic Projection
A method to represent a 3D object on a 2D surface like paper or screen.
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Line of Sight (LOS)
Line of Sight (LOS)
An imaginary line extending from the observer's eye to a point on the object.
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Plane of Projection
Plane of Projection
An imaginary flat surface where the image created by the Line of Sight is projected.
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Orthogonal Projection
Orthogonal Projection
A type of projection where the lines of sight are parallel to each other and perpendicular to the plane of projection.
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Oblique Projection
Oblique Projection
A type of projection where the lines of sight are parallel to each other but not perpendicular to the plane of projection.
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Axonometric Drawing
Axonometric Drawing
A drawing that shows a 3D view of an object, typically using perspective techniques to create a sense of depth.
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Perspective Drawing
Perspective Drawing
A type of drawing that utilizes perspective techniques to create a realistic representation of a 3D object.
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Inclined Line
Inclined Line
A line that is not parallel or perpendicular to the projection planes.
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Inclined Plane
Inclined Plane
A plane (flat surface) that is not parallel or perpendicular to the projection planes.
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Obliqued Line
Obliqued Line
A line that intersects the projection planes at an oblique angle.
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Obliqued Plane
Obliqued Plane
A plane that intersects the projection planes at an oblique angle.
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Curve Line
Curve Line
A line made of curves.
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Curve Surface
Curve Surface
A surface made of curves.
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Direct Measurement (Depth Transfer)
Direct Measurement (Depth Transfer)
A method of transferring depth information from a side view to a front view directly using measurements.
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Miter Line (Depth Transfer)
Miter Line (Depth Transfer)
A line drawn at a 45-degree angle to transfer depth information from one view to another.
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Hidden Line
Hidden Line
A line representing an edge that is not visible from the current viewpoint.
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Center Line
Center Line
A line that starts and ends with a long dash, used to indicate the center of an object or feature.
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Visible Line
Visible Line
A line that represents an edge that can be seen from the current viewpoint.
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Hidden Line Corner
Hidden Line Corner
An intersection between hidden lines that creates a corner resembling the letter L, T, V, or Y.
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Curved Hidden Line
Curved Hidden Line
A hidden line that starts on a center line and represents an edge that cannot be seen from the current viewpoint.
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Small Hole Center Line
Small Hole Center Line
A representation of a small hole, depicted as a single thin line.
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Center Line Extension
Center Line Extension
A center line should not extend between views.
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Center Line Gap
Center Line Gap
There should be a gap between center lines and visible or hidden lines.
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Intersection Line
Intersection Line
A type of line used in multiview drawings to indicate the boundary between two surfaces, forming a visible edge on the object.
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Dashed Line
Dashed Line
A type of line used in multiview drawings to represent an edge that is obscured from view by another surface. It is indicated by a series of short dashes or dots.
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Construction Line
Construction Line
A line used in multiview drawings to indicate features that are not part of the final object. It is typically represented by a thin, light line.
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Edge Line
Edge Line
A line in a multiview drawing signifies an edge when two surfaces meet. If not visible from the viewpoint, it's presented as a dashed line.
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Precedence of Lines
Precedence of Lines
When drawing lines that coincide, the most relevant line takes precedence, covering up the others. The order of importance is visible, hidden, center, then construction lines.
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Rib and Web
Rib and Web
A thin, flat feature of an object, acting as structural support.
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Spoke
Spoke
A rod radiating from the hub to the rim of a wheel.
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Aligned Section
Aligned Section
A section view obtained by rotating the object's features around a symmetry axis, showing them in a principal view.
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Conventional Break
Conventional Break
A technique for representing long objects in drawings by removing a portion and indicating the break with lines.
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Convention for Section Lines
Convention for Section Lines
Omitting section lines in a section view, particularly when the cutting plane passes flatwise through certain features.
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Misleading Impression of Spoke
Misleading Impression of Spoke
Misleading impression can occur using a normal section view of a spoke. It leads to an incorrect interpretation of the spoke's shape.
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Multiple Section View
Multiple Section View
When displaying multiple section views you should show the object at its true shape.
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Chapter 3: Orthographic Projection
- This chapter covers orthographic projection, a method of representing three-dimensional (3D) objects on two-dimensional (2D) media.
- Orthographic projection uses parallel projection lines, normal (orthogonal) to the projection plane.
Contents
- Projection theory
- Multiview drawing
- Line convention
Purpose of Orthographic Projection
- To graphically represent 3D objects on 2D media (e.g., paper, screen).
- This method makes object features transferable for communication, overcoming the inconvenience of communicating 3D objects directly.
Concept of Orthographic Projection
- Based on two variables:
- Line of sight (LOS): An imaginary ray of light between the observer's eye and the object.
- Plane of projection: An imaginary flat plane upon which the image created by the LOS is projected.
Types of Lines of Sight
- Parallel projection: Projection lines are parallel.
- Converge projection: Projection lines converge at a vanishing point.
Line of Sight (LOS) in Orthographic Projection
- The projection lines in orthographic projection are parallel and normal (orthogonal) to the plane of projection.
Orthographic Projection
- In this course, only parallel and orthogonal projections (i.e., orthographic projection) are considered.
- Oblique projection is not covered.
View Types
- Image on a projection plane.
- View depends on the relative orientation between an object and a plane.
- Multiview drawing: Shows a 2D view of an object.
- Axonometric drawing: Shows a virtual 3D view of the object.
Summary of View Types
- The type of views and projections cover aspects of various types: parallel and converge projections, orthogonal, oblique views - including multiview, pictorial, and perspective drawings.
View Comparison
- Multiview drawing:
- Advantage: Accurately depicts object details (size and shape).
- Disadvantage: Requires training for visualization.
- Pictorial drawing:
- Advantage: Easy to visualize.
- Disadvantage: Can lead to shape and angle distortion.
- Perspective drawing:
- Advantage: Object representation resembles how our eyes perceive it.
- Disadvantage: Difficult to create, and often distorts size and shape.
Definition of Multiview Drawing
- A set of related images created by viewing the object from different directions.
- Adjacent views are needed to provide a complete object description. (Height, Width, Depth).
Methods for Creating Multiview Drawings
- Revolve the object with respect to the observer.
- The observer moves around the object.
- Glass box concept: Revolution of the planes of projection (Top view, Front view, Right side view, Rear view, Left side view, Bottom view).
Relative Orientation of Views
- Demonstrates the relationships between different views. (Top view, Front view, Rear view, Left side view, Right side view, Bottom view).
Problem Solving Steps in Multiview Drawing
- Given a 3D representation of an object:
- Identify the features
- Match the identified features with the lines (or areas) in the views.
- Establish line (or plane) types (normal, inclined, oblique)
Object Features in Multiview Drawing
- Edge: Represents the boundary between two faces.
- Surface Limit: Represents the last visible part of the curved surface.
- Surface: Defined area bounded by edges or surface limits (can be plane or curve).
Projection of Lines, Planes, and Curved Features in Multiview Drawings
- Normal lines
- Inclined lines
- Oblique lines, planes and curved objects (including cases of intersection and tangency with adjacent surfaces).
Transferring Depth in Multiview Drawings
- Direct measurement: Use a ruler.
- Miter line: 45-degree line for accurate depth transfer (and precise depth measurement transfer).
Projection of an Object with Curved Surfaces
- Curved surface can be tangent or intersect adjacent planes.
- In intersection, edge becomes a line in the multiview.
- Tangential case: no edge or line in multiview.
Examples of Multiview Drawings
- A variety of objects and their corresponding multiview drawings are given, demonstrating practical applications.
Further Practice
- Suggestions for practicing multiview drawing - Interpretation of lines; Modifying the object and observing changes in the drawing
Types of Planes
- Normal
- Inclined
- Curved surface
Line Conventions
- Precedence of coincide lines
- Hidden line drawing
- Center line drawing
Hidden Line Drawings
- Rules for drawing hidden lines, to show their existence.
- Intersection between hidden lines (forming L, T, V, or Y corners).
- Curve hidden lines starting on center lines. (Detailed applications and examples provided).
Center Line Drawings
- Must start and end with a long dash.
- In circular views, short dashes should cross the center of the circle/arc.
- Center lines should not extend between views.
- For small holes, a center line is presented as a thin continuous line.
- Gap when a centerline continues with a visible or hidden line. (Specific examples provided for appropriate application.)
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