different light intensity (environment) with ground shadow on/off

[LayC42]

just for my understanding - if ground shadows (environment tab) is on / off, the representation of the HDR light is different.

I build up a 'lil scene with a cube and a ground plane. The material of the cube is diffuse white. The HDR environment is a simple studio... .hdr (install content). I forgot to save the scene of the attached images, but I think the description is clear enough (otherwise ask).
The difference between both images is just the ground shadow option!

My question is: Is it normal that the unchecked ground shadow option produce a brighter scene then with ground shadow?


thank you for your help!

[Will Gibbons]

So, this is odd. I tried my own test and found the opposite of what you did.

If I'm not mistaken, ground shadows on would cast shadows onto the ground, which would darken the ground plane that's reflecting light onto your object, thus darkening your object. So, I would expect your object to be darker when ground shadows are on.

I did this and found the exact opposite behavior, which is weird.

Finally, I turned off ground plane and found that turning ground shadows on and off had no effect on the shading of the cube.

[DMerz III]

I've been told when we put in a ground plane as geometry (not the one that loads by default), I should turn off the "ground shadow" box in the environment tab. Odd that you're both getting different results. LayC42's result would be more expected to me because turning the ground shadow checkbox on, would produce "2 shadow layers", thus a darker ground.

[Will Gibbons]

Yes, we've identified this as a bug and it'll be addressed.

D. Merz pointed out what is correct. If you have a ground plane, your object will cast shadows whether you have ground shadows on or not. You'll also get more reflected light from the plane.

If you do not add a ground plane, you won't get shadows when the ground shadows box is left unchecked. However, KeyShot is able to produce ground shadows with no ground plane, which is when that check box comes in handy.

[Finema]

hi
have you test with an other texture than Diffuse ? 

[Will Gibbons]

hi
have you test with an other texture than Diffuse ? 

Same behavior with white paint material.