Perspective view possibilities
2013
Maegi, R., Tallinn Univ. of Technology (Estonia). Centre of Engineering Graphics
Parallel projections are mainly used on technical drawings due to non-deformed images unavoidable for dimensioning. But human vision and photography is based on central projection (perspective) where the centre of projection rays is located in the focus of the eye or the camera. Therefore the perspective view is more realistic and expressive than parallel projection. According to foreshortening the perspective drawings can be divided to one-, two- and three-point perspective. The names of these categories refer to the number of vanishing points in the perspective drawing. Several methods of constructing perspectives exist, including: 1) Freehand sketching (common in art); 2) Graphically 2D-constructing (once common in architecture); 3) 3D-modelling in CAD; 4) Photo-composition with camera. The result of the perspective image depends on some parameters: view angle (Zoom), distance, lights, shadows and other. Too large view angle causes inadvisable deformities of peripheral objects. Additional spatial effects can be obtained from two perspective images using stereoscopic method. 3D-modelling in AutoCAD enables to produce video-clip with moving camera. Modern digital photo-camera allows to create very attractive panoramic image and other effects. Knowing perspective view possibilities gives the availability to create expressive images in drawings and in photography.
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