best you can do because right now you need to know the state of the robot as well as possible so the best you can do is filtering in that situation but what if you're post-processing your data you already collected your data I want to know where was my robot back at time T we should also use the information that happened after and so that's called smoothing and smoothing you use all the sensor observations before and after to come to a conclusion about the distribution over state of your robot or your environment now and the figures had