Resizing HDRI Backdrop can ruin the reflections

Development Rendering
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1

Hello everyone!

I have a question about HDRI Backdrop. After creating it, I made this Orbuculum just to test the reflections. I’ve noticed that reflections depend on the size of the HDRI Backdrop. Sometimes, they tend to get weird or they don’t exist at all. Image 1 is fine, but notice the black line in the second image, or the black void in the third image. Why does HDRI size affect reflections in such a way? What am I missing?

Thanks.

Problem 1_1
Problem 1_11559×868 126 KB

Problem 1_2
Problem 1_21559×868 121 KB

Problem 1_3
Problem 1_31559×868 103 KB

2

Take a look in the code of that backdrop. I can’t remember exactly ( not at a machine rn ), but I think -maybe- the mesh cast shadows…

3

Hi! Thanks for answering. “Cast Shadow” is turned off by default…

Cast Shadow
Cast Shadow539×907 136 KB

4

The only thing that comes to my mind is that the issue could be about the range of luminance, but I haven’t dug out that setting. Notice in picture 3 that the ball is not reflecting the distant building, but it does reflect the nearby grass…

5

Darn.

Not sure, sorry :frowning:

6

Looks like every HDRI backdrop size should be at least 1300, and I’m gonna close this subject with that.