ENG 004 Lecture 4, Oct 9, 2012
Announcements
- Turn in HW #1 now. Place in stack corresponding to your section.
- Four wait listed students have been added.
- Read beginning of Chapter #5
- Lecture HW #2 will be posted after class.
Topics
Drawing Types
3D to 2D, 2D to 3D
Diagrams
Legibility/Communication
Drawing Types
Projection theory is in Chapter 5
Projections and Perspective
- One point perspective
- Two point perspective
- Three point perspective
- Parallel Projection (infinite focal point)
One point perspective
One point perspective
Two point perspective
- Most realistic
- Does not preserve scale
Two point perspective
Two point perspective
Parallel Projections
Parallel projection corresponds to a perspective projection with an
infinite focal length (the distance from the image plane to the projection
point)
Orthographic projection
Parallel project representation of a three dimensional object in two
dimensions
Axonometric
To measure along axes.
Multiview Projections
Up to 6 views of an object are projected onto planes perpendicular to the
coordinate axes. The view positions follow one of two schemes: First Angle or
Third Angle
Pictorial Projections
Image of object from skewed direction to reveal all axes
Isometric, Dimetric, Trimetric
Axonometric Projections
Type of parallel projection, more specifically a type of orthographic
projection, used to create a pictorial drawing of an object, where the object
is rotated along one or more of its axes relative to the plane of
projection
Isometric Projections
All three axes are equally foreshortened and angled 120 degrees apart.
Lines are parallel.
Isometric Projections
Isometric Limitations
Isometric Limitations
Orthographic Axonometric Multiview Projections
Third Angle Projection
Orthographic Multiview Projections
Orthographic Multiview Projections
Oblique
Projects an image by intersecting parallel rays (projectors) from the
three-dimensional source object with the drawing surface (projection
plane).
θ is typically 45 degrees
x-y scales are the same
z scale is between 0 and 1, usually 1/2
Oblique
Drawing Types
Diagrams
Ideas are captured in a visual format using symbols, words, lines,
etc.
- shows relationships
- show critical issues or functions
- organize concepts
- visual note taking
- free form
Types
- Graph based: tree, network, flow chart, Venn
- Chart based: histogram, bar char, pie char, function graph, scatter
plot
- Infographics
Tree diagrams
Flow chart
Represents an algorithm or process
Flow chart: Freehand
Venn diagrams
Show all possible logical relations between a finite collection of
sets
Engineering Diagrams
- Free body diagrams
- Block diagrams
- Circuit diagrams
- Exploded views
- Hydraulic diagrams
- Sankey diagrams
Statics: Free Body Diagrams
Dynamics
Controls: Block Diagrams
Materials: Lattice Diagrams
Fluids: Flow Diagrams
Fluids: Hydraulic Diagrams
Thermodynamics: Sankey Diagrams
Famous Sankey Diagram
Exploded View
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