বিবরণPolyhedron 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.
তারিখ	৬ নভেম্বর ২০০৭
উৎস	Self-made using POV-Ray 3.6 for Windows.
লেখক	Ilmari Karonen
অনুমতি (এ ফাইলের পুনঃব্যবহার)	Public domainPublic domainfalsefalse আমি, এই কাজের স্বত্বাধিকারী, এতদ্দ্বারা আমি এই কাজকে পাবলিক ডোমেইন লাইসেন্সের আওতায় প্রকাশ করলাম। এটি বিশ্বব্যাপী প্রযোজ্য হবে। কিছু দেশে এটি আইনত সিদ্ধ নাও হতে পারে, যদি তাই হয়: আমি যে-কাউকে এই কাজটি যেকোনো উদ্দেশ্যে, বিনাশর্তে ব্যবহারের অনুমতি প্রদান করছি, যদি না সেই শর্তগুলো আইনত প্রয়োজনীয় হয়।
অন্যান্য সংস্করণ	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

POV-Ray source

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