Visual Imaging in the Electronic Age. Drawing Perspective Images

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1 Visual Imaging in the Electronic Age Lecture # 2 Drawing Perspective Images Brunelleschi s Experiment August 25, 2016 Prof. Donald P. Greenberg

2 User Name: art2907 Password:

The Flagellation of Christ, c. 1458-60. Piero della Francesca.

3 The Flagellation of Christ, c Piero della Francesca. Tempera. 59 x 81.5 cm. Urbino, Galleria Nazionale delle Marche.

4 Albrecht Durer. Untitled (Artist using a glass to take a portrait). From Underweysung der Messung mit dem Zirkel und Riichtscheyt, 1st Ed, Woodcut print.

5 Albrecht Durer, Untitled (Two draughtsmen plotting points for the drawing of a lute in foreshortening) From Underweysung der Messung mit dem Zirkel und Riichtscheyt, 1 st Ed., Woodcut print.

6 Light as Rays

7 Light as Waves

8 Light as Photons

9 Planar Geometric Projections Planar Geometric Projections Parallel Perspective Orthographic Oblique One-point Two-point Three-point Multiview Orthographic Axonometric Cavalier Cabinet Isometric Dimetric Trimetric

10 Reference Ingrid Carlbom, Joseph Paciorek. "Planar Geometric Projections and Viewing Transformation," Computing Surveys, vol. 10, no. 4, December (This reference contains a matrix method for combining all of the above types of projections)

11 Orthographic Projections Projectors are perpendicular to the image plane Object faces are parallel to the image plane Diagram from Axonometric and Oblique Drawing: A 3-D Construction, Rendering, and Design Guide by M. Saleh Uddin. New York: McGraw-Hill P. 9.

12 Axonometric Projections Projectors are perpendicular to the image plane Object faces are not parallel to the image plane Diagram from

13 Oblique Projections Projectors are parallel but not perpendicular to the image plane Object faces are parallel to the image plane Diagram from Axonometric and Oblique Drawing: A 3-D Construction, Rendering, and Design Guide by M. Saleh Uddin. New York: McGraw-Hill P. 9.

14 Perspective Projection Projectors are not parallel but converge on a single focal point (eye, camera) Diagram from Axonometric and Oblique Drawing: A 3-D Construction, Rendering, and Design Guide by M. Saleh Uddin. New York: McGraw-Hill P. 9.

15 Comparison of Axonometric & Perspective Drawings What are the advantages of an axonometric drawing? Can measure distances on axonometric. Can t measure distances on perspective.

17 Perspective Projection (2-point) Rays of light travel from the object, through the picture plane, and to the viewer's eye. This is the basis for graphical perspective.

18 1, 2, 3 Point Perspective Animation (Perspective02_wmv)

19 Computer Graphics Perspective Image Generation

20 Model Standard Computer Graphics Pipeline Camera Perspective Transform Raster Operations Image Storage Display

21 Camera Definition Camera View direction Model The camera location, view direction, and frustum must be defined relative to the object.

22 Eye Coordinate System Z Y e The model is described in a right handed coordinate system. X e Z e X Y

23 Eye Coordinate System Y e Picture Plane Note the eye coordinate system is a left-handed coordinate system

24 Left Handed and Right Handed Coordinate Systems z Left Handed z Right Handed x y z y x z y x x y

25 Simple Perspective Transformation Y e Picture Plane P (x s, y s ) Point On Object P(x e, y e, z e ) X e S Z e S Z e = 0 Z e = D

26 Simple Perspective Transformation Y e P(x e, y e, z e ) P (x s, y s ) O D Q S Q Z e z e = 0 display screen Elevation drawn in the Y e, Z e plane.

27 Simple Perspective Transformation xs D x x z e e Dx e s y s ze,, ys D y z e e Dy z To convert to a dimensionless fraction, can divide by the window size S. e e x s Dx Sz e e, y s Dy Sz e e

28 Perspective Projection Picture Plane Object Eye coordinate system Plan or elevation view

29 Pinhole Camera Note that the entire image through the pinhole is totally in focus on a single image plane.

30 Camera Obscura

31 Brunelleschi s Perspective Experiment

32 Brunelleschi

33 Ghiberti s Doors

34 Ghiberti s Doors

36 Brunelleschi

37 Brunelleschi

38 Brunelleschi

40 Brunelleschi s Experiment

41 Brunelleschi s Experiment

42 Brunelleschi Video (render01_wmv)

43 Brunelleschi s Experiment

44 Brunelleschi s Experiment

45 Description of Homework Assignment #1

46 Assignment #1

48 End...

Visual Imaging in the Electronic Age. Drawing Perspective Images

Visual Imaging in the Electronic Age Lecture # 2 Drawing Perspective Images Brunelleschi s Experiment August 27, 2015 Prof. Donald P. Greenberg http://www.graphics.cornell.edu/academic/art2907/ User Name: