Free-hand drawing : a manual for teachers and students (1898)
Cross, Anson K. (Anson Kent), 1862-1944 · Boston : Ginn & Company · leaf 104
Fig. 20. Perspective of a Sphere and Cube. ellipse will appear a circle, and the representation of the cubewill cause the same image in the eye that the cube does. Figs. 18and 20 are distorted because they are made on a vertical pictureplane through which the visual rays pass obliquely. Fig. 21 is… … Fig. 21. A Side View. as to be perpendicular to a line from the spectators eye to the centreof the sphere. This line is the central visual ray and the axis of thecircular cone formed by the visual rays. Since this cone is inter-sected by a picture plane which is perpendicular to its axis,…
Drawing
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