File:Gray square illusion.png

Gray square illusion -- reproduction of Image:Optical.greysquares.arp.600pix.jpg in POV-Ray by PaulStansifer.

Code used: camera{ location <5,5,-5>+<0.5,0,0.5> look_at <0,0,0>+<0.5,0,0.5> right x*image_width/image_height } // value of shadowed white area = 0.8 * 0.4 // value of lit black area = 0.2 * (0.4 + 0.6*2.0) box{ <-1.985,-0.01,-1.985> <2.985,-0.5, 2.985>  pigment{ checker rgb 0.2 rgb 0.8 }  finish{ ambient 0.4 diffuse 0.6 specular 0 phong 0 brilliance 0 } } box{ <0,0,0.015> <-WoodWidth, -0.5, 5+WoodWidth> texture{ T_Wood1 } translate <-2.5, 0, -2.5> rotate y*0 translate <0.5,0,0.5> } box{ <0,0,0.015> <-WoodWidth, -0.5, 5+WoodWidth> texture{ T_Wood1 } translate <-2.5, 0, -2.5> rotate y*90 translate <0.5,0,0.5> } box{ <0,0,0.015> <-WoodWidth, -0.5, 5+WoodWidth> texture{ T_Wood1 } translate <-2.5, 0, -2.5> rotate y*180 translate <0.5,0,0.5> } box{ <0,0,0.015> <-WoodWidth, -0.5, 5+WoodWidth> texture{ T_Wood1 } translate <-2.5, 0, -2.5> rotate y*270 translate <0.5,0,0.5> } cylinder{ <2,0,2> <2,2.5,2>, 0.7  pigment{ rgb <0,0,1> } } light_source{ <5,5,5>  color 2.0 area_light 1.5*x, 1.5*y, 10, 10 adaptive 1 circular orient }
 * 1) include "colors.inc"
 * 2) include "woods.inc"
 * 1) local WoodWidth = 0.25;