In Figure 117, the contour is a circle. It looks deformed, and does not look like a regular circle.

 

(2) Illusion on shifts in line positions and angles

When a straight line and a band are piled up in an acute angle, the straight line is naturally influenced. In this case, the straight line shifts to cause a fault. Then, it makes you feel the shifting line doesn't seem to exist on the extension of the original line (Figs. 311, 312).

Similarly curved lines are also influenced by a crossing band. (Figs. 314, 315)

Three examples of works using the illustrated illusion principles above for fine art and design are shown on the next page (Figs. 316-318).
 
 


311
312
313 		 
314
315

 

Figure 311: Line shifts due to intervention of other diagrams (Illusion by Poggendorf).
Figure 312: Shifting of line by the intervention of space.
Figure 313: Electric wires intersevting in acute angle (upper figure) sometines look separated
                       as shown in the lower figure.
Figure 314: Arches actually meet though they appear not to.
Figure 315: In fact, although ther appear to be a cycloid black and white line, these are 
                       concentric circles.


 

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