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Chapter 3 Orthographic Projection
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TOPICS Object representation Multiview projection Glass box concept
Orthographic projection of point, line, plane, surface and object. Line convention
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OBJECT REPRESENTATION
Axonometric projection Multiview projection
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MULTIVIEW PROJECTION Three principle dimensions of an object …
… can be presented only two in each view. Depth Height Adjacent view(s) is needed to fulfill the size description. Depth Width Height Width Depth
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TO OBTAIN MULTIVIEW REPRESENTATION OF AN OBJECT
Revolve the object with respect to observer. The observer move around the object.
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REVOLVE THE OBJECT Top view Front view Right side view
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OBSERVER MOVE AROUND Top view Front view Right side view
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THE GLASS BOX CONCEPT Rear view Left side view Bottom view
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History Depth Height Width
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Click on the picture to play video
MULTIVIEW PROJECTION Click on the picture to play video
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Click on the picture to play video
MULTIVIEW PROJECTION Click on the picture to play video
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Click on the picture to play video
MULTIVIEW PROJECTION Click on the picture to play video
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Click on the picture to play video
MULTIVIEW PROJECTION Click on the picture to play video
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Orthographic Projection
of Object Features
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OBJECT FEATURES are lines that represent the boundary between two faces. Edges Represent the intersection of two or more edges. Corners Edge Edge No edge Corner No corner No corner
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OBJECT FEATURES are areas that are bounded by edges Surfaces
or limiting element. Surfaces is a line that represents the last visible part of the curve surface. Limitingelement Surface Surface Surface Limit Limit
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PROJECTION OF POINT(S)
BT BT AT Equal distance AT B A BR AF BF AF BF AR BR AR
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PROJECTION OF LINE NORMAL LINE True length Equal length Point
BT AT BT Equal length AT B A BR AF BF AF BF AR BR AR Point True length NORMAL LINE
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PROJECTION OF LINE INCLINED LINE True length Equal length
BT AT BT Equal length AT B A A AF BR BF AF BF AR BR AR Foreshortened Foreshortened INCLINED LINE
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PROJECTION OF LINE OBLIQUED LINE Foreshortened Equal length
BT AT BT B Equal length BR BF AT B A BF BR AF A AF AR AR Foreshortened Foreshortened OBLIQUED LINE
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PROJECTION OF PLANE NORMAL PLANE True size Equal length Edge Edge CT
BT CT AT Equal length BT AT C B A CR BF AF,CF BF AF,CF AR,BR CR AR,BR Edge Edge NORMAL PLANE
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PROJECTION OF PLANE INCLINED PLANE Foreshortened Equal length Edge
BT CT AT C Equal length BT CR AT CF C B CF CR A BF AF AR,BR BF AF AR,BR Edge Foreshortened INCLINED PLANE
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PROJECTION OF PLANE OBLIQUED PLANE Foreshortened Equal length
BT CT AT C Equal length B CR BT AT BF CF C B CF BR BR CR BF A AF AR AF AR Foreshortened Foreshortened OBLIQUED PLANE
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PROJECTION OF OBJECT The views are obtained by projecting all object features to the picture plane. You have to project the remaining surfaces which are invisible too !
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PROJECTION OF OBJECT s s s
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PROJECTION OF OBJECT
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Line Convention
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LINE CONVENTION Precedence of coincide lines. Hidden line drawing.
Center line drawing.
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PRECEDENCE OF LINE Order of importance Visible line Hidden line Center
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HIDDEN LINE PRACTICE Hidden line should join a visible line, except it extended from the visible line. Leave space Correct Join No !
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HIDDEN LINE PRACTICE Hidden line should join a visible line, except it extended from the visible line. Leave space Leave space Correct No !
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HIDDEN LINE PRACTICE Hidden line should intersect to form L and T corners. L T Correct No !
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HIDDEN LINE PRACTICE Hidden arcs should start on a center line.
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CENTER LINE PRACTICE In circular view, short dash should cross at the intersections of center line. For small hole, center line is presented as thin continuous line. Center line should not extend between views. Leave space Leave space
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CENTER LINE PRACTICE Leave the gap when centerline forms a continuation with a visible or hidden line Center line should always start and end with long dash. Leave space Leave space Leave space Leave space
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