talking about white colors in the ground, you can see in this video MINUTE 1:29 the IR/UV system was calibrated under a shadow tree, ground is dark with many white and yellow branche spread all over the ground ,and same everywere,however IR/UV pick a signal ,a coin , of course if I move to a sunlight area the IR start beep becouse of INTENSE SUNLIGHT, so we need calibrate according place of searching conditions,thats obvious,
https://www.youtube.com/watch?v=xfQMOTmv2Eg