• the only objects in the scene are generic spheres, which may have been
  • scaled
  • translated
  • rotated with respected to an axis
    
    
• the only attribute of the generic sphere is an assigned (emissive) color
  
• the camera is set up
  • at position (eye_x, eye_y, eye_z),
    
  • looking at point (look_at_x, look_at_y, look_at_z), with
    
  • the original up-direction for the camera being <up_x, up_y, up_z>.
    
    
• speed-up has been accomplished by more wisely computing the ray's direction, for each ray.
  
  
• the scene (including camera information and sphere information) has been described in a file using Scene Description Language