描述Polyhedron with no vertex visible from center.png	This simple, non-convex polyhedron is constructed so that none of its 24 vertices, marked with black balls, can be seen from a region around its center. This counterexample shows that placing observers at each vertex is not a solution to the 3-dimensional generalization of the art gallery problem. The blue faces are also not visible from the center. This polyhedron is topologically equivalent to the rhombicuboctahedron.
日期	2007年11月6日
来源	Self-made using POV-Ray 3.6 for Windows.
作者	Ilmari Karonen
授权 (二次使用本文件)	Public domainPublic domainfalsefalse 我，本作品著作权人，释出本作品至公有领域。这适用于全世界。 在一些国家这可能不合法；如果是这样的话，那么： 我无条件地授予任何人以任何目的使用本作品的权利，除非这些条件是法律规定所必需的。
其他版本	Outside view with the blue faces removed, showing the construction more clearly. View from the inside facing one of the corners. Panoramic 180 view from the inside. Vector version with cross-section

This is the source code from which the image above is rendered. The permission given above applies to this source code as well.

// Persistence of Vision Ray Tracer Scene Description File
// File: 3d-art-gallery.pov
// Vers: 3.6
// Desc: A simple polyhedron with none of the vertices visible from the center.
// Date: 2007-11-06
// Auth: Ilmari Karonen

// parameters controlling the width and depth of hidden gaps
#declare a = (1 - 1/3);
#declare b = (1 + 2/3);

#if (b <= 1/a)
  #warning "B too small for a, vertices will be visible from center!"
#end

// textures for various surfaces
#declare T1 = texture {
  pigment { color rgb<1.0, 0.8, 0.8> }
  finish { ambient 0.3 diffuse 0.7 }
}
#declare T2 = texture {
  pigment { color rgb<1.0, 1.0, 0.8> }
  finish { ambient 0.3 diffuse 0.7 }
}
#declare T3 = texture {
  pigment { color rgb<0.8, 0.9, 1.0> }
  //pigment { color rgb 0 transmit 1 }
  finish { ambient 0.3 diffuse 0.7 }
}
#declare T4 = texture {
  pigment { color rgb<0.8, 0.8, 0.8> }
  finish { diffuse 0.3 specular 1.0 }
}

// the polyhedron itself
mesh { 
  // corner triangles
  triangle { < 1, a, b>, < a, b, 1>, < b, 1, a> texture { T1 } }
  triangle { < 1, a,-b>, < a, b,-1>, < b, 1,-a> texture { T1 } }
  triangle { < 1,-a, b>, < a,-b, 1>, < b,-1, a> texture { T1 } }
  triangle { < 1,-a,-b>, < a,-b,-1>, < b,-1,-a> texture { T1 } }
  triangle { <-1, a, b>, <-a, b, 1>, <-b, 1, a> texture { T1 } }
  triangle { <-1, a,-b>, <-a, b,-1>, <-b, 1,-a> texture { T1 } }
  triangle { <-1,-a, b>, <-a,-b, 1>, <-b,-1, a> texture { T1 } }
  triangle { <-1,-a,-b>, <-a,-b,-1>, <-b,-1,-a> texture { T1 } }

  // visible sides
  triangle { < 1, a, b>, < 1,-a, b>, < 1, a,-b> texture { T2 } } 
  triangle { < 1,-a,-b>, < 1,-a, b>, < 1, a,-b> texture { T2 } } 
  triangle { <-1, a, b>, <-1,-a, b>, <-1, a,-b> texture { T2 } } 
  triangle { <-1,-a,-b>, <-1,-a, b>, <-1, a,-b> texture { T2 } } 

  triangle { < a, b, 1>, <-a, b, 1>, < a,-b, 1> texture { T2 } } 
  triangle { <-a,-b, 1>, <-a, b, 1>, < a,-b, 1> texture { T2 } } 
  triangle { < a, b,-1>, <-a, b,-1>, < a,-b,-1> texture { T2 } } 
  triangle { <-a,-b,-1>, <-a, b,-1>, < a,-b,-1> texture { T2 } } 

  triangle { < b, 1, a>, < b, 1,-a>, <-b, 1, a> texture { T2 } } 
  triangle { <-b, 1,-a>, < b, 1,-a>, <-b, 1, a> texture { T2 } } 
  triangle { < b,-1, a>, < b,-1,-a>, <-b,-1, a> texture { T2 } } 
  triangle { <-b,-1,-a>, < b,-1,-a>, <-b,-1, a> texture { T2 } } 

  // hidden sides
  triangle { < 1, a, b>, < b, 1, a>, < 1, a,-b> texture { T3 } }
  triangle { < b, 1,-a>, < b, 1, a>, < 1, a,-b> texture { T3 } }
  triangle { < 1,-a, b>, < b,-1, a>, < 1,-a,-b> texture { T3 } }
  triangle { < b,-1,-a>, < b,-1, a>, < 1,-a,-b> texture { T3 } }
  triangle { <-1, a, b>, <-b, 1, a>, <-1, a,-b> texture { T3 } }
  triangle { <-b, 1,-a>, <-b, 1, a>, <-1, a,-b> texture { T3 } }
  triangle { <-1,-a, b>, <-b,-1, a>, <-1,-a,-b> texture { T3 } }
  triangle { <-b,-1,-a>, <-b,-1, a>, <-1,-a,-b> texture { T3 } }

  triangle { < a, b, 1>, < 1, a, b>, < a,-b, 1> texture { T3 } }
  triangle { < 1,-a, b>, < 1, a, b>, < a,-b, 1> texture { T3 } }
  triangle { <-a, b, 1>, <-1, a, b>, <-a,-b, 1> texture { T3 } }
  triangle { <-1,-a, b>, <-1, a, b>, <-a,-b, 1> texture { T3 } }
  triangle { < a, b,-1>, < 1, a,-b>, < a,-b,-1> texture { T3 } }
  triangle { < 1,-a,-b>, < 1, a,-b>, < a,-b,-1> texture { T3 } }
  triangle { <-a, b,-1>, <-1, a,-b>, <-a,-b,-1> texture { T3 } }
  triangle { <-1,-a,-b>, <-1, a,-b>, <-a,-b,-1> texture { T3 } }

  triangle { < b, 1, a>, < a, b, 1>, <-b, 1, a> texture { T3 } }
  triangle { <-a, b, 1>, < a, b, 1>, <-b, 1, a> texture { T3 } }
  triangle { < b, 1,-a>, < a, b,-1>, <-b, 1,-a> texture { T3 } }
  triangle { <-a, b,-1>, < a, b,-1>, <-b, 1,-a> texture { T3 } }
  triangle { < b,-1, a>, < a,-b, 1>, <-b,-1, a> texture { T3 } }
  triangle { <-a,-b, 1>, < a,-b, 1>, <-b,-1, a> texture { T3 } }
  triangle { < b,-1,-a>, < a,-b,-1>, <-b,-1,-a> texture { T3 } }
  triangle { <-a,-b,-1>, < a,-b,-1>, <-b,-1,-a> texture { T3 } }
}

// mark vertices with black spheres
sphere { < 1, a, b>, 0.03 texture { T4 } }
sphere { < a, b, 1>, 0.03 texture { T4 } }
sphere { < b, 1, a>, 0.03 texture { T4 } }
sphere { < 1, a,-b>, 0.03 texture { T4 } }
sphere { < a, b,-1>, 0.03 texture { T4 } }
sphere { < b, 1,-a>, 0.03 texture { T4 } }
sphere { < 1,-a, b>, 0.03 texture { T4 } }
sphere { < a,-b, 1>, 0.03 texture { T4 } }
sphere { < b,-1, a>, 0.03 texture { T4 } }
sphere { < 1,-a,-b>, 0.03 texture { T4 } }
sphere { < a,-b,-1>, 0.03 texture { T4 } }
sphere { < b,-1,-a>, 0.03 texture { T4 } }
sphere { <-1, a, b>, 0.03 texture { T4 } }
sphere { <-a, b, 1>, 0.03 texture { T4 } }
sphere { <-b, 1, a>, 0.03 texture { T4 } }
sphere { <-1, a,-b>, 0.03 texture { T4 } }
sphere { <-a, b,-1>, 0.03 texture { T4 } }
sphere { <-b, 1,-a>, 0.03 texture { T4 } }
sphere { <-1,-a, b>, 0.03 texture { T4 } }
sphere { <-a,-b, 1>, 0.03 texture { T4 } }
sphere { <-b,-1, a>, 0.03 texture { T4 } }
sphere { <-1,-a,-b>, 0.03 texture { T4 } }
sphere { <-a,-b,-1>, 0.03 texture { T4 } }
sphere { <-b,-1,-a>, 0.03 texture { T4 } }

sky_sphere {
  pigment { color rgb 1 }
}

// outside lights
light_source { <50, 80, 0> color rgb 0.2 area_light 5*x 5*y 9, 9 adaptive 0 jitter circular orient parallel point_at <0, 0, 0> rotate  15*y }
light_source { <50,-10, 0> color rgb 0.1 area_light 5*x 5*y 9, 9 adaptive 0 jitter circular orient parallel point_at <0, 0, 0> rotate  45*y }
light_source { <50, 20, 0> color rgb 0.3 area_light 5*x 5*y 9, 9 adaptive 1 jitter circular orient parallel point_at <0, 0, 0> rotate  75*y }
light_source { <50, 80, 0> color rgb 0.2 area_light 5*x 5*y 9, 9 adaptive 0 jitter circular orient parallel point_at <0, 0, 0> rotate 135*y }
light_source { <50,-10, 0> color rgb 0.1 area_light 5*x 5*y 9, 9 adaptive 0 jitter circular orient parallel point_at <0, 0, 0> rotate 165*y }
light_source { <50, 20, 0> color rgb 0.3 area_light 5*x 5*y 9, 9 adaptive 1 jitter circular orient parallel point_at <0, 0, 0> rotate 195*y }
light_source { <50, 80, 0> color rgb 0.2 area_light 5*x 5*y 9, 9 adaptive 0 jitter circular orient parallel point_at <0, 0, 0> rotate 255*y }
light_source { <50,-10, 0> color rgb 0.1 area_light 5*x 5*y 9, 9 adaptive 0 jitter circular orient parallel point_at <0, 0, 0> rotate 285*y }
light_source { <50, 20, 0> color rgb 0.3 area_light 5*x 5*y 9, 9 adaptive 1 jitter circular orient parallel point_at <0, 0, 0> rotate 315*y }

// inside lights
light_source { <0, 0, 0> color rgb 0.5 area_light 0.6*x 0.6*z 9, 9 adaptive 1 jitter circular orient }
light_source { <0, 0, 0> color rgb 0.5 area_light 0.4*x 0.4*z 9, 9 adaptive 1 jitter circular orient }

// cameras
camera { location <8.0, 5.0, -5.0> angle 30 look_at <0.0, 0.0,  0.0> right x*image_width/image_height }  // outside
//camera { panoramic location <0,0,0> look_at <1,0,1> angle 180 } // inside, 180 degree panorama
//camera { location <0,0,0> look_at <1,1,1> angle 70 }  // inside, looking at corner