def __init__(self,token,imgfile=None,pointsfile=None):
        if token not in rs.TOKENS:
            raise ValueError("Token %s not found."%(token))

        self._token = token
        self._imgfile = imgfile
        self._pointsfile = pointsfile
        self._img = None     # img data
        self._points = None  # [[x],[y],[z],[v]]
        self._shape = None   # (x,y,z)
        self._max = None     # max value