Describe EXTRACT_DATA_PIC here.

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{{{
      SUBROUTINE EXTRACT_DATA_PIC(NTMP,QSZ,SCALE,PICNM,IPL,
     .                     V,UX,UY,UZ,HUSE,HT,CP,SP,EUSE,ETOL,
     .                     FINV,DPIC_DLOC,DIDH,DJDH,Z0,KK,ESZ,DN, DNX)
}}}

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 *      INTEGER               NTMP
  NTMP is a global compile parameter that defines the maximum size of maplets (it allocates memory)
   Standard value is 128

 *      INTEGER               QSZ
  QSZ is the half size of maplet.  width = QSZ * 2 + 1
   It is derived from [[READ_MAP]]

 *      DOUBLE PRECISION      SCALE
  The scale (both horizontally x and y, as well as verticlally).  The values in the [[MAPLET]] should be multiplied by this value to get its actual value.  Units are in km.
   It is derived from [[READ_MAP]]

 *      CHARACTER*12          PICNM
  The name of the image that you want to use.  The file is read in (again) in this program)

 *      DOUBLE PRECISION      IPL(2)
  IPL = Image Pixel Line.  Scaling factor to translate from physical to image frame.
   Comes from [[V2IMGPLV]]



 *      DOUBLE PRECISION      V(3)
  Central vector of the maplet
   It is derived from [[READ_MAP]]

 *      DOUBLE PRECISION      UX(3)
 *      DOUBLE PRECISION      UY(3)
 *      DOUBLE PRECISION      UZ(3)
  Normal plane of the maplet in X, Y and Z space
   It is derived from [[READ_MAP]]

 *      LOGICAL               HUSE(-NTMP:NTMP,-NTMP:NTMP)
  Tracks each pixel of the maplet to define if its value should be considered
   Defined in [[HGT2SLP]] 


 *      REAL*4                HT(-NTMP:NTMP,-NTMP:NTMP)
  HT - Height.  The height of the template at that location of the maplet.  Used for trying to identifing shadow.


 *      DOUBLE PRECISION      CP(3)
  Camera vector
   Calculated in this subroutine

 *      DOUBLE PRECISION      SP(3)
  Sun vector
   Calculated in this subroutine


 *      LOGICAL               EUSE
  "Expanded T1" Flag for when to use the expanded threshold for DN.  
  Is a flag set within [[lithos]] or [[lithosp]] using the 'x' option
   Uses the ETOL variable

 *      DOUBLE PRECISION      ETOL
  Expanded T1 flag variable. 
  Is a flag set within [[lithos]] or [[lithosp]] using the 'x' option
   Typically set to .025 (standard within the scripts for LITHOSP)


 *      DOUBLE PRECISION      FINV
  Reports the fraction of invisible pixels within the maplet/image intersection
  
 *      DOUBLE PRECISION      DPIC_DLOC(2,3)
   This subroutine computes the change in the image-space location (p,l) of a point (x,y,z) on a maplet as the point is moved in the maplet frame.
    Changed within [[LOC2PIX]] that is typically called from this subroutine.



 *      DOUBLE PRECISION      DIDH 
 *      DOUBLE PRECISION      DJDH
  Rate of change for the position I and J in the picture
   Calcualted in this routine and reported back to who called it

 *      INTEGER               Z0(2)
  Center point to extract the data from the image.
   Defined in [[lithos]] and derived from IPL.  Used in [[PICINPT]] and [[BRT1]]

 *      INTEGER               KK, ESZ
  * KK is a spacing parameter, which I think is based upon the maplet.
  * ESZ is the size of the array.
   Defined in [[lithos]].  Used in [[PICINPT]] and [[BRT1]]

 *      INTEGER               DN(-1300:1300,-1300:1300)
  The workspace of displayed DN for both the image and the maplet (template)
   Set in this subroutine.

 *      REAL*4                DNX(-NTMP:NTMP,-NTMP:NTMP)
   '''The filled out data that we really want.'''  Set in this routine.

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[[categorySubroutine]]