3Learning Objectives Define spatial visualization. Explain the relationship between an orthographic projection and a multiview drawing.Identify and define the three dimensions of an object.Define the six principal views and the three regular views.Identify the three principal projection planes.
4Learning ObjectivesExplain three visualization principles for multiview drawings.Identify the three types of flat surfaces.Explain characteristics of cylindrical surfaces.Explain characteristics of fillets, rounds, and runouts.Identify differences between third-angle and first-angle projection.Discuss computer-generated views.
5The Role of Spatial Skills Spatial visualization can be defined as the mental visualization of 2D and 3D shapes and objects, including such tasks as imagining objects in the mind as they are rotated, moved, or reflected in a mirror
6Spatial Visualization Tools Visualization of rotationsAnswer: B
7Spatial Visualization Tools Mental rotation with two correct rotationsAnswer: A and C
8Spatial Visualization Tools Surface development testAnswer: B
9Spatial Visualization Tools Mental visualization of folding and unfoldingAnswer: D
10Orthographic Projection Created by projecting the points of a three-dimensional object onto a two-dimensional plane
11Multiview ProjectionOrthographic projection consisting of systematically arranged views to describe an object
12Definition SummaryOrthographic projection, multiview projection, and multiview drawing are interchangeable termsRepresents the main type of drawing views used in industrial prints
13Selection of Views Six principal views: Front Back Top Bottom Right sideLeft side
14Selection of Views Three “regular” views commonly used in education: FrontTopRight side
16Dimensions of an Object Height is how tall the object is, as measured on the front viewWidth is how wide the object is, as measured on the front viewDepth is how deep the object is from front to backEach dimension appears twice in the three regular views“Length” and “breadth” are terms not used
25Meanings of a Multiview Line A—Edge view of a flat or curved surfaceB—Intersection of two surfaces (just an edge)C—Maximum contour of a curved surface
26First-Angle and Third-Angle Projection Dividing space into quadrantsHistorical development of projection theory used two planes to divide spaceAfter projections, the two planes are revolved into one, with quadrants two and four “collapsed”
30Computer-Generated Views The benefits of creating views directly from the 3D model include:Ease of constructionEase of changeAccuracy in representing geometryIntelligent association between the model and the annotations
31Computer-Generated Views Views created by the CAD program may need:Individual line adjustment for weight or dash spacingThe representation of fillets, rounds, and runouts adjusted (see A versus B to the right)Conventional practices reviewed
32What do you see?Print supplied by Sunnen Products Company.