gistfile1.md

For ROS navigation, there is a tf tree map->odom->base_link. The odom pose is the base_link frame pose relative to odom frame. The absolute/global pose is the base_link frame pose relative to map frame. IMU and encoders provide the odom pose which drifts over time and thus only right for a short time. GPS, amcl and indoor position system provide the absolute/global pose. You got odom pose means you got the tf odom->base_link, and you got absolute/global pose means you got base_link pose relative to map. To correct the robot location, you have to provide the tf map->odom, which can be calculated from odom->base_link and base_link pose relative to map.