function output = getPointIndexInVolume(obj, pointsCoordinates)
  % the output are the three indices of the given points in the given volume.
  indicesX = obj.getPointsIndicesX(pointsCoordinates(:,1));
  indicesY = obj.getPointsIndicesY(pointsCoordinates(:,2));
  indicesZ = obj.getPointsIndicesZ(pointsCoordinates(:,3));
  output = [indicesX, indicesY, indicesZ];
end