;Find the bounding box, the smallest rectangle with sides parallel to the grid which 
;circumscribes all the 'true' values in a 2D boolean array
; Input
;   map - 2d array of booleans
; 
; returns
;   an array of 4 integers. First two are row and column of one corner of the box, 
;   second two are row and column of opposite corner of the box
function findbbox,map,status=status
  w=where(map,n_map)
  status=0
  if n_map eq 0 then begin
    status=-1
    return,[-1,-1,-1,-1]
  end

  n=min(w)
  x=max(w)

  c1=(array_indices(map,n))[1]
  c2=(array_indices(map,x))[1]

  tmap=transpose(map)
  w=where(tmap)
  n=min(w)
  x=max(w)

  r1=(array_indices(tmap,n))[1]
  r2=(array_indices(tmap,x))[1]

  return,[r1,c1,r2,c2];
end