[ros-users] stereo calibration topic requirements?

[Patrick Beeson]

Eric, Adam, Patrick,

Here is the diff of my working camera_calibration fix to get two 
independent camera timestamps "close enough" to at least test 
calibration (and see that Stereo calibration is not working at all).



Index: nodes/cameracalibrator.py
===================================================================
--- nodes/cameracalibrator.py	(revision 28602)
+++ nodes/cameracalibrator.py	(working copy)
@@ -60,11 +60,23 @@

  class CalibrationNode:

+    def mineA(self, msg):
+        self.lasttime = msg.header.stamp
+
+    def mineB(self,msg):
+        diff = msg.header.stamp-self.lasttime
+        sec = diff.to_sec()
+        if abs(sec) < 0.09:
+            msg.header.stamp = self.lasttime
+
      def __init__(self, chess_size, dim):
          self.chess_size = chess_size
          self.dim = dim
+        self.lasttime = rospy.Time.now()
          lsub = message_filters.Subscriber('left', sensor_msgs.msg.Image)
+        lsub.registerCallback(self.mineA)
          rsub = message_filters.Subscriber('right', sensor_msgs.msg.Image)
+        rsub.registerCallback(self.mineB)
          ts = message_filters.TimeSynchronizer([lsub, rsub], 4)
          ts.registerCallback(self.queue_stereo)


Eric Perko wrote:
> Hey Adam,
> 
> I'm trying to do stereo calibration as well and running into the exact
> same problem. I'm switching from boxturtle to latest to see if that
> will solve the problem. If you do 'rostopic list -v' you will probably
> see /image listed as being subscribed to, but having unknown type,
> meaning nothing is publishing it yet. At least that is the behavior I
> get. However, I was still having the same hanging behavior even after
> commenting out the line in cameracalibrator.py where it subscribes to
> /image, so it may or may not be the root problem.
> 
> My understanding is that when publishing to a /camera_info topic, the
> timestamps for the camera_info and the image_raw should be synced, so
> you have to publish at whatever rate you publish your image. I could
> be wrong, but that is my understanding from the discussion surrounding
> a previous problem I was having with image_proc not working with
> camera1394.
> 
> - Eric
> 
> On Tue, Apr 6, 2010 at 7:24 PM, Adam Leeper <aleeper at stanford.edu> wrote:
>> Hi all-
>>
>> I'm trying to calibrate a pair of cameras for stereo. I only have the
>> following topics:
>>
>>  * /my_stereo/left/image_raw [sensor_msgs/Image] 1 publisher
>>  * /my_stereo/right/image_raw [sensor_msgs/Image] 1 publisher
>>
>> That is, I don't have any topics publishing mono camera info or anything.
>>
>> I do
>> rosrun camera_calibration cameracalibrator.py
>> right:=/my_stereo/right/image_raw left:=/my_stereo/left/image_raw
>> left_camera:=/my_stereo/left right_camera:=/my_stereo/right
>>
>> but it just hangs. Since mono calibration works fine, my only guess is that
>> the stereo routine requires the mono calibration info to proceed, so it is
>> waiting for more topics before continuing. If so, the tutorial should
>> probably mention that, because right now it just says "check to see that
>> there is a left and right image_raw topic".
>>
>> On a related note, what is the proper way to publish camera info? Do I write
>> a node that just publishes the message every few seconds? It seems that the
>> camera info doesn't change quickly :)
>>
>>
>> Thanks!
>> --Adam
>>
>>
>>
>>
>> Adam Leeper
>> Stanford University
>> aleeper at stanford.edu
>> 719.358.3804
>>
>> _______________________________________________
>> ros-users mailing list
>> ros-users at code.ros.org
>> https://code.ros.org/mailman/listinfo/ros-users
>>
>>
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