Cannot use ros::Time::now() before the first NodeHandle has been created or ros::start() has been called.

[liborw]

Under Hydro the following minimal example

#!/usr/bin/env python

import roslib; roslib.load_manifest('sandbox')
import rospy
import tf

if __name__ == '__main__':
    rospy.init_node("test_tf_listener")
    listener = tf.TransformListener()
    (trans, rot) = listener.waitForTransform('test_1', 'test_2', rospy.Time(0), rospy.Duration(0))

result in this error:

$ rosrun sandbox test_tf_listener.py 
terminate called after throwing an instance of 'ros::TimeNotInitializedException'
  what():  Cannot use ros::Time::now() before the first NodeHandle has been created or ros::start() has been called.  If this is a standalone app or test that just uses ros::Time and does not communicate over ROS, you may also call ros::Time::init()
Aborted (core dumped)

[liborw]

I have tried it in gdb and this is the back trace:

(gdb) bt
#0  0x00007ffff68e1425 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff68e4b8b in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007ffff34c069d in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#3  0x00007ffff34be846 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#4  0x00007ffff34be873 in std::terminate() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#5  0x00007ffff34be96e in __cxa_throw () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#6  0x00007ffff41777d4 in ros::Time::now() () from /opt/ros/hydro/lib/librostime.so
#7  0x00007ffff397714c in tf2_ros::Buffer::canTransform(std::string const&, std::string const&, ros::Time const&, ros::Duration, std::string*) const ()
   from /opt/ros/hydro/lib/libtf2_ros.so
#8  0x00007ffff4ae6aea in tf::Transformer::waitForTransform(std::string const&, std::string const&, ros::Time const&, ros::Duration const&, ros::Duration const&, std::string*) const () from /opt/ros/hydro/lib/python2.7/dist-packages/tf/_tf.so
#9  0x00007ffff4adac99 in ?? () from /opt/ros/hydro/lib/python2.7/dist-packages/tf/_tf.so
#10 0x0000000000466254 in PyEval_EvalFrameEx ()
#11 0x000000000057bd02 in PyEval_EvalCodeEx ()
#12 0x000000000057c77d in PyRun_FileExFlags ()
#13 0x000000000057e4a1 in PyRun_SimpleFileExFlags ()
#14 0x0000000000512cfd in Py_Main ()
#15 0x00007ffff68cc76d in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
#16 0x000000000041ba51 in _start ()

So it looks that the tf is using tf2 and the problem is somewhere there.

[tfoote]

This is a reoccurance of this patched issue: 70defb15617da5029c54eca640c2f217a2b8fb43

[tfoote]

The cleaner solution is to use the python tf2 buffer class.

[tfoote]

Actually a problem in tf2_ros fixed here: https://github.com/ros/geometry_experimental/commit/5e41627775cb5d2ce536a5127261d41a57f0a3d7

[liborw]

Can You post a simple example how to get transformation from the tf2, I have tried all tutorial I could found and none of the worked.

[jonbinney]

@liborw not sure if you still need this, but here's a simple example for tf2 in python:

#!/usr/bin/env python                                                                                                                                                                                                                                                                  
import sys
import rospy
import math
import tf2_ros
import turtlesim.msg
import turtlesim.srv

rospy.init_node('tf_turtle')

buf = tf2_ros.Buffer()
listener = tf2_ros.TransformListener(buf)

# wait a second for frames to accumulate. buf.lookup_transform seems to fail immediately if it hasn't yet                                                                                                                                                                              
# gotten any transfroms for the 'odom' frame, instead of waiting for the timeout                                                                                                                                                                                                       
rospy.sleep(1.0)

try:
    tform = buf.lookup_transform('odom', 'base_link', rospy.Time(0), timeout=rospy.Duration(4))
except (tf2_ros.LookupException, tf2_ros.ConnectivityException, tf2_ros.ExtrapolationException) as e:
    print e

print 'Success'
print tform

[liborw]

This helps a bit but what I missing is wait for transform.

[jonbinney]

From my understanding, that should now be built into lookup_transform, which is why the "timeout" arg is passed in.

[liborw]

However, this probably still doesn't work:

This is the call:

tform = self.tfb.lookup_transform(source_frame, target_frame, stamp, timeout=rospy.Duration(10))

And the error:

Lookup would require extrapolation into the future.  Requested time 1383123031.108603954 but the latest data is at time 1383123031.101570845, when looking up transform from frame [a] to frame [b]

[jonbinney]

Yeah i've had that problem too. Seemed like a bug to me

[jdddog]

Is there a fix for this that doesn't involve shifting to tf2?

[tfoote]

There was a second issue with the sleep failing due to being uninitialized.

I believe that I have fixed the issue here: 0a034c5 Can someone verify that this works for them? You will need to checkout geometry_experimental into your workspace from geometry_issue_30 branch.

[jdddog]

Awesome, it works for me, thanks for fixing it!

The code at the very top wont work fyi, because waitForTransform returns None. So I tested it with this:

#!/usr/bin/env python

import roslib; roslib.load_manifest('beginner_tutorials')
import rospy
import tf
import sys, traceback

if __name__ == '__main__':
    rospy.init_node("test_tf_listener")
    listener = tf.TransformListener()

    try:
        listener.waitForTransform('camera_link', 'camera_rgb_frame', rospy.Time(), rospy.Duration(5.0))
        (trans, rot) = listener.lookupTransform('camera_link', 'camera_rgb_frame', rospy.Time())
        print str(trans) + " " + str(rot)
    except:        
        traceback.print_exc(file=sys.stdout)

[tompe17]

I got bitten by the same bug and i do not want to convert to tf2 now. So will the fix above be available soon in hydro? Or do I need to check out the branch?

[tfoote]

This change is in 0.4.8 It's available in the testing debian repo at the moment, but has not been synced to the public repo: http://www.ros.org/debbuild/hydro.html?q=geometry_experimental

A sync can be expected in the next week or so. We've had a pattern of syncing approximately every 2 weeks.

[loulansuiye]

terminate called after throwing an instance of 'ros::TimeNotInitializedException' what(): Cannot use ros::Time::now() before the first NodeHandle has been created or ros::start() has been called. If this is a standalone app or test that just uses ros::Time and does not communicate over ROS, you may also call ros::Time::init() Aborted (core dumped)

[loulansuiye]

when I use roscpp function ros::init(argc,argv,"name") ,it report the up problem

[tfoote]

@loulansuiye This is a years closed issue for a completely different component in a different language. If you'd like some help please ask a question on answers.ros.org