perm filename INTRO[0,BGB] blob
sn#178662 filedate 1975-09-30 generic text, type C, neo UTF8
COMMENT ⊗ VALID 00003 PAGES
C REC PAGE DESCRIPTION
C00001 00001
C00002 00002 {λ10FAαINTRODUCTION.P1I425,0JCFA} SECTION 0.
C00007 00003 {W0,675JUFA
C00011 ENDMK
C⊗;
{λ10;FA;αINTRODUCTION.;P1;I425,0;JCFA} SECTION 0.
{JCFD} INTRODUCTION.
{JU;λ7;FM}
"For the purpose of presenting my argument I must first
explain the basic premise of sorcery as don Juan presented it to me.
He said that for a sorcerer, the world of everyday life is not real,
or out there, as we believe it is. For a sorcerer, reality or the
world we all know, is only a description. For the sake of validating
this premise don Juan concentrated the best of his efforts into
leading me to a genuine conviction that what I held in mind as the
world at hand was merely a description of the world; a description
that had been pounded into me from the moment I was born."
{JR;FM} - Carlos Castaneda. ~Journey to Ixtlan~.
{JU;I1150,0;λ10;FA}
This thesis is about computer techniques for handling 3-D
geometric descriptions of the world; the world that can be visually
perceived with a television camera. The overall design idea may be
characterized as an inverse computer graphics approach to computer
vision. In computer graphics, the world is represented in sufficient
detail so that the image forming process can be numerically simulated
to generate synthetic television images; in the inverse, perceived
television pictures (from a real TV camera) are analysed to compute
detailed geometric models. For example, the polyhedra in Figure 0.1
on page two were computed from views of a plastic horse on a turntable.
It is hoped, that visually acquired 3-D geometric models can be of
use to other robotic processes such as manipulation, navigation or
recognition.{Q;
L0,475;H2;*HORS01.PLT;
L0,-475;H2;*HORS02.PLT;
L0,0;JA;JC;FA} FIGURE 0.1 - HORSE SHAPED POLYHEDRA DERIVED FROM VIDEO IMAGES.
{W0,675;JU;FA;
} Once acquired, a 3-D model can be used to anticipate the
appearance of an object in a scene, making feasible a quantitative
form of visual feedback. For example, the appearance of the two
machine parts depicted in Figure 0.2 can be computed and analyzed
(top halves of Figures 0.3 and 0.4) and compared with an anaylsis of
an actual video image of the parts (bottom halves of Figures 0.3 and
0.4). By comparing the predicted image with a perceived image, the
correspondence between features of the internal model and features of
the external reality can be established and a corrected location of
the parts and the camera can be measured.
{W0,1250;↓;I300,800;FA}FIGURE 0.2{H2;L415,510;*PUMP02;↑;JU;FA;}
Finally by way of introduction, I wish to emphasive that the
kind of vision being attempted is metric rather than linguistic and
that the results achieved to date are modest. Feature classification
and recognition in terms of English words is not being attempted,
rather a system of prediction and correction between a 3-D world
model and a sequence of images is contemplated. The chapters of this
thesis proceed twice from theory through an implementation, with the
first five chapters dealing with modeling and the last five chapters
dealing with vision. Theory on geometric modeling is in Chapter 1
and theory on computer vision in Chapter 6. The implementation
consists of two main programs named GEOMED and CRE. GEOMED is a
system of 3-D modeling routines with which arbitrary polyhedra may be
constructed, altered, or viewed in perspective with hidden lines
eliminated; and CRE is a solution to the problem of finding intensity
contours in a sequence of television pictures and of linking
corresponding contours between pictures. Auxiliary programs perform
top level task control, comparing and locus solving.
{Q;L0,475;*PUMP3.VID;L0,-475;*PMP3.VID;
L0,0;JA;JC;FA} FIGURE 0.3 - PREDICTED VIDEO ↑ AND PERCEIVED VIDEO ↓.
{Q;L0,475;H2;*PUMP04.PLT;L0,-475;H2;*PUMP03.PLT;
L0,0;JA;JC;FA} FIGURE 0.4 - PREDICTED IMAGE ↑ AND PERCEIVED IMAGE ↓.