Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!leah!itsgw!steinmetz!uunet!portal!cup.portal.com!Classic_-_Concepts
From: Classic_-_Concepts@cup.portal.com
Newsgroups: comp.graphics
Subject: Re: 3-D perceptual abilities
Message-ID: <15375@cup.portal.com>
Date: 4 Mar 89 18:48:53 GMT
References: <2493@masada.cs.swarthmore.edu> <238@anselm.UUCP>
Organization: The Portal System (TM)
Lines: 27


  >  If there were no shadows everything would look flat.  Anyone agree or
  >  disagree with me?

I disagree.  I can think of a number of other visual cues that we use to
measure volume and distance, for example:
 
     1.  Color changes with distance and around edges.  I mean colors other
         than shadows.  Like looking at the horizon and seeing things
         darker there.
     2.  You would still get 'perspective' as you looked at objects, due to
         narrowing in the distance (like a road), or smaller, like a person
         standing at a distance compared to one standing close by.
     3.  Fuzzy versus sharp.  Our vision allows us to focus more clearly on
         closer objects (except of course, in cases of people requiring
         corrective lenses for their eyes) and objects in the distance fuzz
         out gradually.
There may be others, but just off the cuff, without thinking about it for
more than a few seconds, those are ones that come to mind.     -LH

Wait a moment, I just thought of some others.  If there were no shadows, we
might rely more on other senses, like smell and hearing.  They also provide
distance cues, e.g., you're standing in front of a school bus, the amount of
diesel smell might provide cues as to the length of the bus, or the volume
of engine noise could contribute to our 'perception' of how flat it appears.
So without shadows, things might appear flat at first, but I wouldn't be
surprised if we adapted rather quickly and relied on other sources of info.