Find a Position Where a Certain Amount of Bloom is Located

Ok, this is a bit complicated to explain lol, but ill do it in the best way possible

so i have been looking at some pics from a roblox game called “Motorsport”, by a group of developers by the name of sythdev

one thing i noticed is how they had a different looking bloom, which i am assuming are billboard guis, however the bloom was also reflection based (which is in the pic below)

Problem/what i need

i have geniunely no idea how to do this, but i basically would like to find the position of a certain amount of bloom, like if a bloom is big in this spot it will (insert function here), also i would also like to find the material of where the bloom is as well.

help would be greatly appreciated, thx peeps!

Does this help out?
<How to make metal more reflective? - #2 by iccletus

im more looking for the position of where bloom reflects off of the object, sorta kinda like this:

with roblox reflections thingy, if you look at an object at a certain angle it will put this white bloom there, which i would want to find the position of that place where that bloom is