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)