odom_topic and odom_frame

[aviadoz]

Hi,

I want to know what are the advantages and disadvantages of using odom_topic instead of odom_frame.
I know that odom_fram takes from tf.

Thanks,
Aviad
 

[matlabbe]

Hi,

You mean odom_topic and odom_frame_id from rtabmap.launch.

- When using odom_topic, the twist covariance is used in the neighbor links of rtabmap's graph. This will affect how the graph is optimized on loop closures. In area that odometry is less confident (larger covariance), on graph optimization, the graph will be deformed more in those areas.

- When using odom_frame_id, odometry is taken from TF. As TF is used, we don't have any covariance. Normally, we should also set odom_tf_linear_variance and odom_tf_angular_variance to set a fixed covariance to neighbor links in rtabmap's graph (default values here). The disadvantage of this approach is that all links have the same covariance, so the graph will be deformed equally along all the map. The advantage is that if odometry doesn't provide covariance or it is not compatible with rtabmap's graph optimization (if you have warnings from rtabmap about very large covariance values), we can override it using TF and set the related parameters for convenience.

cheers,
Mathieu