I have one transform that is determined at run-time, during startup, and never changes. It's only used for visualization, and I'd rather not trouble the node that determines it with having to rebroadcast it periodically, a la static_transform_publisher, nor have to communicate it to another node to do that job.

Pat

On Tue, May 25, 2010 at 10:29 AM, Josh Faust <jfaust@willowgarage.com> wrote:
If transforms are also being broadcast at the current time, it's going to be limited by whatever the cache time is on the TransformListener being used.  rviz uses 10 minutes (which is probably a bit high), but anything using the default time will be limited to 10 seconds.

10 minutes was chosen as "arbitrarily high", so that rviz would always work over spotty wireless.  It should probably be lowered to a minute or so.  The downside to a large cache time is that it can negatively affect performance.

Why are you trying to future date transforms?

Josh

On Mon, May 24, 2010 at 10:33 PM, Patrick Bouffard <bouffard@eecs.berkeley.edu> wrote:
Is there a limitation on how far in the future the timestamp of a transform broadcast by a tf::TransformBroadcaster can be? If there was I would have expected it to be perhaps the default tf cache time of 10.0 seconds, but my experimentation (this is with boxturtle) seems to indicate it is 600 seconds. In particular, I'm looking at the frame in rviz, and if I set the timestamp to ros::Time::now() + ros::Duration(600.1), then I get the following warning in rviz, and the frame does not have the right data:

No transform from [/grey/camera] to frame [/enu]

... however if I simply change the 600.1 to 600, there is no warning..

It looks like the constructor in rviz's frame_manager.cpp is where this happens:

FrameManager::FrameManager()
{
  tf_ = new tf::TransformListener(ros::NodeHandle(), ros::Duration(10 * 60), false);
}

It looks like this is unchanged in trunk as well. Is there is some reason why ten minutes was chosen? Are there drawbacks to making this longer? Or configurable? Ten minutes is fine for my present application but it seems to be somewhat arbitrary.

Thanks,
Pat

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