[comp.ai] 3-D Reconstruction and Trinocular Vision

djb@LAFITE.BELLCORE.COM.UUCP (04/11/87)

In a recent posting Dave Chassin writes:


>  I know there are some people who have already done some work in these areas,
>  but it has always amazed me how little is in fact published. I have NO, get
>  that, NO references relating to 3D reconstructions other than the following,


          There has recently  been  a   lot   of   published
work   on  stereo   reconstruction   from  image pairs.  The
work appears for the most part in  two   bi-annual   confer-
ences:  International  Conference  on  Pattern  Recognition,
and  the  International  Joint  Conference  on    Artificial
Intelligence.   On   alternate   years  there  are  US  ver-
sions entitled AAAI  (American  Association  for  Artificial
Intelligence)  and  CVPR (Computer Vision and Image Process-
ing).

          The situation was different in the mid-1970's when
the only  stereo  work  available  existed  in the form of a
few hard-to-locate PhD theses and some  NASA-sponsored  work
on  the  Mars  rover.   Part  of the problem was the lack of
availability of video frame grabber hardware  and  the  high
cost   of  quality   low  noise  cameras.   When you add the
amount of computing needed  to  perform  even   the   lowest
level   of   image analysis  (e.g. edge extraction) it is no
wonder that little attention  was  given  to  multiple-image
problems.


>  That is that you will need to create some sort of algorithm for generating a
>  3D model from 2D information received by the cameras. Essentially the idea
>  is to analyse a pair of images, extract the boundary data, assemble a 2D
>  'image' for each view, project the two images together into a 3D 'image',


          My thesis  ("On Computer Stereo Vision  with  Wire
Frame Models,"  University  of  Illinois,  Urbana,  January,
1978) addressed two different problems   in   stereo   robot
vision.   The   first  problem  was  to automatically recon-
struct  a  3-D  wire  frame  of  an  object  from   multiple
views.    The  second  problem  was  to align a pre-existing
wire frame model (constructed by hand) to the  partial   3-D
wire  frame  derived from the images.

          I  described  a   three-view   stereo    technique
which  corrected   some  of  the  existing  problems associ-
ated with binocular stereo.  The three views are arranged in
a   triangle.    This  arrangement  reduces  matching  ambi-
guity  and increases triangulation accuracy  for  edge  com-
ponents   parallel to  the  disparity direction.     I  sug-
gested that more than  three  views   could   be   used   to
further   enhance   the  signal-to-noise   ratio.     Others
later applied a similar technique to  successfully  guide an  
autonomous robot vehicle.

     The  second  part  of  the  system   aligned   a   pre-
constructed  wire  frame  model  of the object to the image-
derived wire frame.  It was  entirely  automatic  and  could
even align partially occluded objects.  This allowed a robot
to "see" an object and grasp it.

     The document is available as a Technical  Report  from:
Coordinated  Science   Laboratory, University  of  Illinois,
Urbana, IL 17604 .  The thesis is available from: University
Microfilms,  Ann Arbor,  Michigan.  A  short paper  appeared
in the Fifth International Joint  Conference  on  Artificial
Intelligence,  MIT, Cambridge,  MA,  1977,   co-authored  by 
D. J. Burr   and   R.  T.  Chien,   entitled   "A System for 
Stereo  Computer  Vision  with  Geometric  Models".


D. J. Burr, 2A-397
Bell Communications Research
435 South Street
Morristown, NJ 07960

email: djb@bellcore.com