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What means 'ground truth'

asked 2014-07-20 12:39:54 -0500

Chipiron gravatar image

I dont know what 'ground truth' means. My project use a 'ground truth to tf' node and gazebo publish some 'ground truth' topic that seems an Odometry message.

What does it means?

What is it intended for?

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answered 2014-07-20 15:02:50 -0500

ahendrix gravatar image

In robotics, "Ground Truth" is the most accurate measurement available. New methods, algorithms and sensors are often quantified by comparing them to a ground truth measurement. Ground truth can come either directly from a simulator, or from a much more accurate (and expensive) sensor.

In gazebo, this is the exact position of your robot within the simulator.

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Thanks for the reply ahendrix. What absolute origin of coordinates does groundtruth refers to in gazebo? And what should be in a real SLAM enviroment? The exact position known by the observer? Do you know what i mean?

Chipiron gravatar image Chipiron  ( 2014-07-20 17:32:24 -0500 )edit

I'm not sure where gazebo puts the origin for the ground truth frame. You should be able to figure it out by visualizing it in rviz.

ahendrix gravatar image ahendrix  ( 2014-07-20 17:43:02 -0500 )edit

On a real robot, ground truth can be provided indoors by a highly-accurate motion capture system such as a Vicon, or outdoors ground truth can be obtained through differential GPS.

ahendrix gravatar image ahendrix  ( 2014-07-20 17:44:32 -0500 )edit

Very thanks ahendrix, now its more clear! I did not find anything relevant on the web :(

Chipiron gravatar image Chipiron  ( 2014-07-20 18:05:38 -0500 )edit

I'll quibble with Austin's definition a little. Ground truth is the actual information that you're trying to estimate with a sensor. For odometry, it's the actual position of the robot, delivered by a simulation or estimated (with high accuracy) by high-accuracy sensors...

Bill Smart gravatar image Bill Smart  ( 2014-07-21 02:10:41 -0500 )edit

... Technically, no sensor can give you ground truth, since they're making measurements, but good ones (like the ones Austin mentions) can give you measurements that are close enough to ground truth that they can be treated as being such.

Bill Smart gravatar image Bill Smart  ( 2014-07-21 02:12:17 -0500 )edit

@ahendrix did u try with motion capture/stereo for ground truth?

tsdk00 gravatar image tsdk00  ( 2018-10-30 00:41:43 -0500 )edit

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Asked: 2014-07-20 12:39:54 -0500

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Last updated: Jul 20 '14