Screen Space Reflections (SSR) Falloff

Hey guys,

Just getting stuck into learning UE4 the last couple days and had an issue with the ssr, is it possible to change the boundaries of where it falls off. I find it quite distracting when I’m panning my camera and it’s already clipping the sides, and bottom.
I understand the reasoning, just want to know if there are any controls that can’t make it extend further out by a little bit so it’s not vanishing in an obvious way.

Thanks, having a fun time playing around with this too.


You can’t extend it further than it has data for, I don’t know if there’s a setting for the fade though that determines how far that goes.

ok. i’ll keep looking but nothing fruitful yet. thank you darthviper.

It’s generally meant to be used with pre-calculated cubemaps, or maybe light propogation volumes if you have that enabled. By itself the effect doesn’t look very good as you’ve noticed.

i might try LPV then…still have so much to test out. thanks for the suggestion.

LPVS do not support a dynamic reflection environment just yet. So switching to those will not help you (since metals will look white and everything reflective has a strange white shine on it). However, this missing stuff will get added in the future and then you might be better off with the LPVs :wink:

actually, simply using a skylight to fill in the blanks has worked out good enough for me to not notice the ssr falloff. be nice if that was animatable, even just rotation, think it’s in the works…

Screen space reflections, as the name implies reflects only the colors on screen. Once the ray escapes the screen there is no more valid data so the contribution fades out to the next valid reflection source, typically reflection captures. To avoid the hard edge of the screen shape there is a falloff as it approaches the edge of the screen. That function is hard coded in the shader. I wouldn’t bother trying to change it. I didn’t find much benefit in different functions. The current one looks nice and is cheap.

Updating a cubemap around the camera would be expensive. Using screen space colors is convenient because they already exist. One idea to improve this artifact is to keep around screen space data in a cubemap from when the camera looked in that direction.