void initViewer(pcl::visualization::PCLVisualizer &viewer) {
	viewer.setBackgroundColor(0, 0, 0);
	viewer.addCoordinateSystem(1.0, "reference");
	viewer.initCameraParameters();
	viewer.setRepresentationToPointsForAllActors();
	viewer.setCameraPosition(0, 0, -1, 0, 0, 0, 0, -1, 0);
	viewer.registerKeyboardCallback(keyboardCallback);
}