Descriptive Geometry ■ One can easily visualize the corresponding situation in 3D.However,it is also necessary to be able to go back and forth between 2D and 3D.That is,be able to: represent a given three dimensional situation by a series of 2D views (i.e.,orthographic views- principal and auxiliary) visualize (and derive pertinent geometric information about)the three dimensional situation from a given set of orthographic views. Shanghai Jiao Tong University 6
Shanghai Jiao Tong University 6 Descriptive Geometry n One can easily visualize the corresponding situation in 3D. However, it is also necessary to be able to go back and forth between 2D and 3D. That is, be able to: n represent a given three dimensional situation by a series of 2D views (i.e., orthographic views— principal and auxiliary) n visualize (and derive pertinent geometric information about) the three dimensional situation from a given set of orthographic views
Spatial Visualization There are two types of projections to communicate engineering and technical illustration work pictorial projections multiview projections Shanghai Jiao Tong University 7
Shanghai Jiao Tong University 7 Spatial Visualization n There are two types of projections to communicate engineering and technical illustration work n pictorial projections n multiview projections
Pictorial projections Pictorial projections consist of single view drawings that are suitable for representing preliminary ideas or sketches,but are not appropriate for communicating technical data. Examples of pictorial projections are the oblique,isometric or perspective projections (or views) Shanghai Jiao Tong University 8
Shanghai Jiao Tong University 8 Pictorial projections n Pictorial projections consist of single view drawings that are suitable for representing preliminary ideas or sketches, but are not appropriate for communicating technical data. Examples of pictorial projections are the oblique, isometric or perspective projections (or views)
Examples PICTORIAL OBLIQUE PROJECTION PERSPECTIVE PROJECTION ISOMETRIC PROJECTION Shanghai Jiao Tong University 9
Shanghai Jiao Tong University 9 Examples
multiview projections Multiview drawings present multiple different views of the same object.This method presents projections of the same object on three planes simultaneously,namely the top, front and side (or profile)planes,providing three views known as the principal views.All dimensions are drawn to scale and the three principal views can be used to form additional views known as auxiliary views. Shanghai Jiao Tong University 10
Shanghai Jiao Tong University 10 multiview projections n Multiview drawings present multiple different views of the same object. This method presents projections of the same object on three planes simultaneously, namely the top, front and side (or profile) planes, providing three views known as the principal views. All dimensions are drawn to scale and the three principal views can be used to form additional views known as auxiliary views