Download presentation
Presentation is loading. Please wait.
Published byRobert Shelton Modified over 6 years ago
1
Engineering Geometry Engineering geometry is the basic geometric elements and forms used in engineering design. Engineering and technical graphics are concerned with the descriptions of shape, size, and operation of engineered products. The shape description of an object relates to the positions of its component geometric elements in space. To be able to describe the shape of an object, you must understand all of the geometric forms, as well as how they are graphically produced.
2
Coordinate Space 2-D Space: Cartesian coordinate system:
A 2-D coordinate system establishes an origin at the intersection of two mutually perpendicular axes, labeled X (horizontal) and Y (vertical). The origin is assigned the coordinate values of 0,0. X: positive to the right of the origin, and negative to the left. Y: positive above the origin, and negative below Polar coordinate system: Distance from the origin (0,0), and angle measured from the positive X-axis. Distance is always positive. Counterclockwise angle is positive; clockwise is negative.
3
2-D Cartesian coordinate system
4
3-D Coordinate Space Cartesian coordinate system
Three mutually perpendicular axes (X, Y, and Z) intersect at the origin (0,0,0) The right-hand rule is used to determine the positive direction of the axes. A rectangular prism is created using the 3-D coordinate system by establishing coordinate values for each corner. Cylindrical coordinates locate a point on the surface of a cylinder by specifying a distance and an angle in the X-Y plane, and the distance in the Z direction. Spherical coordinates locate a point on the surface of a sphere by specifying an angle in one plane, an angle in another plane, and one height. Absolute coordinates vs. Relative coordinates World coordinate system vs. Local coordinate system
5
3-D Cartesian coordinate system
6
Locating points
7
Right-hand rule for axes directions
8
Cylindrical coordinates
9
Spherical coordinates
10
Geometric Elements Point, Line, Circle, Arc
Parallel lines, perpendicular lines, intersecting lines Tangent line Curved lines: single curved vs. double curved Circle: points equidistant from one point (the center) circumference, radius, chord, diameter, secant, semicircle, arc, sector, quadrant, segment, tangent, concentric circles
11
Circle definitions
12
Geometric Elements Conic sections: formed by intersection of a plane with a right circular cone Parabola: set of points equidistant from a fixed point (focus), and a fixed line (directrix) Hyperbola: set of points whose distances from two fixed points (foci) have a common difference Ellipse: set of points whose distances from two fixed points (foci) have a constant sum Polygons and Polyhedrons; prisms and pyramids
13
Ellipse
14
HYPERBOLA
15
PARABOLA
16
ELLIPSE
17
CIRCLE
18
Quadrilaterals
19
Polygons
20
Regular polyhedra
21
Prisms
22
Pyramids
23
Design Visualization A dynamic process between the mind, the eyes, and some physical stimulus such as a drawing or an object.
24
Hand/eye/mind connection
25
Solid Object Features Edges – lines that represent the boundary between two faces of an object. Faces – areas of uniform or gradually changing lightness and are always bounded by edges. Limiting element – a line that represents the farthest outside feature of a curved surface. Vertex – point where more than two edges meet.
26
Solid object features
27
Visualization Techniques
Solid Object Combinations and Negative Solids Cutting Planes Normal Rotated about single axis – inclined face Rotated about two axes – oblique face Planes of Symmetry Developments – flattened “skin” of object
28
Combining solid objects
29
Removing solid objects
30
Removing solid objects
31
Subtracting progressively larger wedges
32
Subtracting progressively larger pyramids
33
Additive and subtractive techniques can be used to make a solid geometric form
34
Normal cutting plane
35
Cutting plane rotated about single axis
36
Cutting plane rotated about two axes
37
Cutting plane rotation
38
Planes of symmetry
39
Surface cutting planes
40
Development
41
Image plane
42
Object-image plane orientation
43
Normal faces
44
Camera metaphor
45
Normal face projection
46
Edge views of normal face
47
Inclined face projection
48
Inclined and normal faces
49
Oblique face projection
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.