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From: prem@geomag.gly.fsu.edu (Prem Subrahmanyam)
Newsgroups: comp.graphics
Subject: Re: Lunar Distortions
Keywords: raytracing, distortions.
Message-ID: <1437@sun13.scri.fsu.edu>
Date: 20 Nov 90 18:53:53 GMT
References: <27332@cs.yale.edu> <1097@shakti.ncst.ernet.in>
Sender: news@sun13.scri.fsu.edu
Organization: Florida State University Geology Dept.
Lines: 26

In article <1097@shakti.ncst.ernet.in> dilip@ncst.ernet.in (Dilip Khandekar) writes:
>ellipsoid in a ray-traced image which uses this model. But the distortion is
>prominent only for spheres located in extreme corner of the scene.
>
>   I also encountered the same problem and would be interested in any method
>or projection-model which circumvents this problem. If the pin-hole camera
>model is not a good model for the human eye-brain system then is there any
>other model which is more accurate?
>
>- dilip

   A solution I can see is to have each pixel, instead of having a
   calculated position on a viewing plane, have each instead with
   a calculated horizontal and vertical angle from the center.  
   Knowing the angles, one can easily construct a vector of the
   appropriate angles to represent this pixel's ray.  I have not
   actually implemented this, but it is obvious that this would
   work, as when a conventional method is used and the viewing
   plane is located far from the eye point, the near-spherical
   approximation of the plane is good enough to remove most
   any distortion.  The reason why a conventional camera does
   well is due to the same phenomenon -- it takes a spherical
   "bunch" of rays and maps them to the film plane.
   If I ever get my present thesis out of the way, I will 
   attempt to implement this in my version of DBW_Render.
   ---Prem Subrahmanyam