Describe EXTRACT_DATA_PIC here.

{{{
      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)
}}}


*      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]]

*      DOUBLE PRECISION      CP(3)
  Camera vector
  Calculated in EXTRACT_DATA_PIC

*      DOUBLE PRECISION      SP(3)
  Sun vector
  Calculated in EXTRACT_DATA_PIC


*      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)
*      DOUBLE PRECISION      DIDH
*      DOUBLE PRECISION      DJDH
*      INTEGER               Z0(2)
*      INTEGER               KK, ESZ
*      INTEGER               DN(-1300:1300,-1300:1300)
*      REAL*4                DNX(-NTMP:NTMP,-NTMP:NTMP)