From: tjroberts137@sbcglobal.net   
      
   On 7/30/19 1:49 AM, Nicolaas Vroom wrote:   
   > When I walk away from a building the observed height from my point   
   > decreases. This is a pure optical effect and has no physical   
   > implications i.e. the height of the buiding does not change.   
      
   But it CAN have physical implications. For instance, if you want to   
   photograph the building, close up it won't fit in the camera's aperture,   
   but far away it will.   
      
   Note this is a geometrical projection, which is directly analogous to   
   "time dilation" and "length contraction". For them, relative motion   
   varies the projection, while for your example it is distance that varies   
   the projection.   
      
   Tom Roberts   
      
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