SUBROUTINE  PLTBV (Z1,ZE,Z2,NX,MX,NY)

C     [BIRDSEYE VIEW]
C     [18-DEC-74]

      DIMENSION   ZE(1)
      DATA        HX,HY/4.50,3.25/

      F(I,J)=(R*ZS)/(Z0-ZE(I+MX*(J-1)))

      K=1
      R=5.0
      Z0=1.3*Z2
      ZS=0.125*(Z2-Z1)
      DX=(1.75*HX)/FLOAT(MX-1)
      DY=(1.75*HY)/FLOAT(NY-1)
      X=-0.875*HX
      Y=-0.875*HY
      DO 20 J=1,NY
      I1=((NX+1)-K*(NX-1))/2
      I2=((NX+1)+K*(NX-1))/2
      EF=F(I1,J)
      CALL PLTMS (EF*X,EF*Y,.FALSE.)
      DO 10 I=I1,I2,K
      EF=F(I,J)
      CALL PLTMS (EF*X,EF*Y,.TRUE.)
   10 X=X+DX
      DX=-DX
      X=X+DX
      K=-K
   20 Y=Y+DY
      DX=-(1.75*HX)/FLOAT(MX-1)
      DY=-(1.75*HY)/FLOAT(NY-1)
      X= 0.875*HX
      Y= 0.875*HY
      K=-1
      DO 40 I=1,MX
      J1=((NY+1)-K*(NY-1))/2
      J2=((NY+1)+K*(NY-1))/2
      EF=F(MX-I+1,J1)
      CALL PLTMS (EF*X,EF*Y,.FALSE.)
      DO 30 J=J1,J2,K
      EF=F(MX-I+1,J)
      CALL PLTMS (EF*X,EF*Y,.TRUE.)
   30 Y=Y+DY
      DY=-DY
      Y=Y+DY
      K=-K
   40 X=X+DX
      RETURN

      END