there's a map surface at a certain distance the reading you'll get back is within maybe two centimeters like maybe with denigration 2 centimeters around the proper distance reading something like that so that thing is your calibrated sensor and that you can you can get a distribution for but what actually ugly will be distribution over state given that reading will depend on the prior X what you thought ahead of time might be likely states of your system and so they combined together and then of course is a normalization to make sure things sum