Regarding your first question, you want to set the setMaxIntervalDuration. As far as I understand from a quick look at the sources, a higher value for setAgePenalty makes the algorithm more sloppy for older messages (to get them out of the queue faster) and setInterMessageLowerBound allows to set a minimum delay between messages of a single input of your filter (messages arriving faster than that will be dropped).
As for the second question, you can just feed a SimpleFilter as an input to your Synchronizer:
#include <ros/ros.h>
#include <image_transport/subscriber_filter.h>
#include <message_filters/pass_through.h>
#include <message_filters/simple_filter.h>
#include <message_filters/subscriber.h>
#include <message_filters/sync_policies/approximate_time.h>
#include <sensor_msgs/Image.h>
void callback(const sensor_msgs::Image::ConstPtr& imagemessage1,
const sensor_msgs::Image::ConstPtr& imagemessage2) {
}
int main(int argc, char ** argv) {
ros::init(argc, argv, "test_synchronizer");
ros::NodeHandle nodehandle;
image_transport::ImageTransport imagetransport{nodehandle};
image_transport::SubscriberFilter imagesubscriber1;
imagesubscriber1.subscribe(imagetransport, "/image1", 32);
image_transport::SubscriberFilter imagesubscriber2;
imagesubscriber2.subscribe(imagetransport, "/image2", 32);
message_filters::PassThrough<sensor_msgs::Image> passthrough(imagesubscriber2);
message_filters::SimpleFilter<sensor_msgs::Image> & simplefilter = passthrough;
using MyPolicy = message_filters::sync_policies::ApproximateTime<
sensor_msgs::Image, sensor_msgs::Image>;
MyPolicy mypolicy(32);
mypolicy.setMaxIntervalDuration(ros::Duration(1.e-3));
message_filters::Synchronizer<MyPolicy> synchronizer{
static_cast<const MyPolicy &>(mypolicy), imagesubscriber1, passthrough};
synchronizer.registerCallback(boost::bind(&callback, _1, _2));
ros::spin();
return EXIT_SUCCESS;
}
Originally posted by Maarten with karma: 206 on 2018-03-08
This answer was ACCEPTED on the original site
Post score: 2
Original comments
Comment by jlin on 2018-03-09:
Thanks so much! Somehow the program failed to link with undefined reference to `image_transport::ImageTransport::ImageTransport(ros::NodeHandle const&)'. I'm on ROS 1 kinetic. Probably my environment is not set up right.
Comment by Maarten on 2018-03-09:
You probably just need to add image_transport to your package.xml file (<depend>image_transport</depend>). And install the ros-kinetic-image-transport package if it's not yet installed, but I suppose you would get a compiler error and didn't get to the linking phase if it wasn't installed.