Hi, I asked once before (sorry cannot find that thread again!), but I think I worked out where the weird bottom up light is coming from. For example, There is no light from below, only a directional light above pointing downloads. Where is the bounce light coming from? I started a new "HDRP 'outdoor' scene" and put a sphere in it. The bottom looks lighter. I put a big cube above it (so the sphere is in the shadow). The bottom still looks lighter. I tried an eye dropper to sample the color in case an optical illusion. At the bottom its #36302E. At the top its #19243E - overall, it is darker (but more blue). The cube and sphere are both using the default HD material. If I turn off the cube and Sky and Fog Volume created in such scenes, its even more pronounced. Turns out with in Visual Environment, with Sky Type = Physically Based Sky and Ambient Mode = Dynamic you get the glow from underneath. Change it to "static" and it goes away! Static however is documented to use baked lighting for the sky and I am using 100% real time lighting. So I put it back to Dynamic. Then I finally found "Ground Tint" under "Physically Based Sky". I set that to black (it was brown), and the weird underglow goes away! So finally solved the problem.