Odometry tf relationship is backward with default param values in odometry_integration.cpp

[sayali-purdue]

As per ROS conventions (REP 105), '/odom' is usually the parent of '/base_footprint'. However, in the code odometry_integration.cpp, the following tf is being published: '/base_footprint' -> '/odom'. Is there any particular reason that you prefer to use the backward tf relationship? I am curious to know about it, because it is recommended that we follow the ROS conventions to make the code reusable as well as operable with other ROS packages.

[sayali-purdue]

Upon further code inspection, I found that car_params.yaml specifies the correct values for the frame_id related params. It sets world_frame to 'odom' and base_frame to 'base_footprint'. However, the default parameter values in the source code file, odometry_integration.cpp, are reversed, i.e. default value of base_frame is 'odom' and default value of world_frame is 'base_footprint'. Therefore, if the parameter values are not provided, then these default values are used to publish the transform (base_footprint -> odom). To make to code more robust, the default values should be changed.

Thanks!