multiple messages sync with tf

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Hello,

I am trying to write a callback where two topics and tf are synchronized. For example I want to have an image, a pointcloud and tf at the same time.

I inspired from the piece of code below, which deals with one topic and tf. Does anybody know how to extend tf:MessageFilter to two or more topics?

Thanks

 tf::TransformListener tf_;
 tf::MessageFilter<sensor_msgs::PointCloud2> * tf_filter_;
 message_filters::Subscriber<sensor_msgs::PointCloud2> cloud2_sub_;

//initialisation
cloud2_sub_.subscribe(n, "/kinect/rgb/points2", 10);
tf_filter_ = new tf::MessageFilter<sensor_msgs::PointCloud2>(cloud2_sub_, tf_, "/map", 10);
tf_filter_->registerCallback( boost::bind(&PointReader::pointCloudCallback, this, _1) );

//callback
void pointCloudCallback(const sensor_msgs::PointCloud2::ConstPtr& sensor_msg)
{