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C00002 00002 {≥G⊂CαLOCUS SOLVINGλ30P95JUFA}
C00004 00003 ⊂9.4 Sun Locus Solving: A Simple Solar Emphemeris.⊃
C00007 00004 ⊂9.5 Related and Future Locus Solving Work.⊃
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⊂9.3 Object Locus Solving: Silhouette Cone Intersection.⊃
After the camera location, orientation and projection are
known; 3-D object models can be constructed. The silhouette cone
intersection method is a conceptually simple form of wide angle,
stereo recontruction. The idea arose out of an original intention to
do "blob" oriented visual model aquistion, however a 2-D blob came to
be represented by a silhouette polygon and a 3-D blob consquently
came to be represented by a polyhedron. The present implementation
requires a very favorably arranged viewing environment (white objects
on dark backgrounds or vise versa); application to more natural
situations might be possible if the necessary hardware (or software)
were available for extracting depth discontinuities by bulk
correlation. Furthermore, the restriction to turntable rotation is for
the sake of easy camera solving; this restriction could be lifted by
providing stronger feature tracking for camera calibration.
⊂9.4 Sun Locus Solving: A Simple Solar Emphemeris.⊃
The location of the sun is useful to a robot vehicle vision
system both for sophisticated scene intrepretation and for avoiding
the blunder of burning holes in the television vidicon. The
approximate position of the sun in the sky is readily computed from
the time, date, latitude and longitude using circular approximations.
{λ10;JAF3;}
PROCEDURE SUNLOCUS (REAL DAY,TIME,LAT,LONG; REFERENCE REAL SUNAZM,SUNALT);
BEGIN
REAL RHO,PHI,TMP,ECLIPTIC;
COMMENT POSITION OF THE SUN ON THE ECLIPTIC IN THE CELESTIAL SPHERE;
ECLIPTIC← ((23+27/60)*PI);
RHO ← 2*PI*DAY/365.25
EAST ← SIN(RHO)*COS(ECLIPTIC);
NORTH ← SIN(RHO)*SIN(ECLIPTIC);
ZENITH ← COS(RHO);
COMMENT LOCAL MERIDIAN OF LONGITUDE;
COMMENT LOCAL SOLAR TIME = (24 HOUR PACIFIC STANDARD TIME - 8 MINUTES 44 SECONDS);
PHI ← PI*(1-TIME/12) - ATAN2(EAST,ZENITH);
TMP ← ZENTITH*COS(PHI) - SIN(PHI)*EAST;
EAST ← EAST*COS(PHI) + SIN(PHI)*ZENITH;
ZENITH ← TMP;
COMMENT ROTATE CLOCKWISE IN THE NORTH/ZENITH PLANE TO LOCAL LATITUDE;
TMP ← COS(LAT)*ZENITH + SIN(LAT)*NORTH;
NORTH ← COS(LAT)*NORTH - SIN(LAT)*ZENITH;
ZENITH ← TMP;
CONVERT TO ANGULAR MEASURES;
SUNAZM ← ATAN2(NORTH,EAST);
SUNALT ← PI/2 - AOCS(ZENTIH);
END "SUNLOCUS";
{λ30;JUFA;}
⊂9.5 Related and Future Locus Solving Work.⊃
Although the bulk of this chapter concerned camera solving
using one view of three points the multi view camera calibration is
probably more important to continous image processing but I have very
little to contribute at this time to the existing collection of hill
climbing error minimizing methods.
I have always disliked the multi dimensional hill climber approach
and have sought a more geometric and intuitive solution to the
problem; so far I have only turned up a hill climber in fewer
dimensions (three degrees of freedom) involving six tonged forks
which are rotated about iron circle in two planes Orbiting forks
sweep out families of hyperbolic sheets which leaves one with a set
of contrainted second order equations in one parameter, which might
yet have a closed form anayltic solution.