Can Reshade use data from what's off-screen?

As someone who doesn't use Reshade or ENB, this has always kind of confused me. Is it possible for Reshade to use data from what's off-screen?

Screen-Space Reflections are usually pretty okay, but sometimes might have issues. Using purely screen-space sometimes tends to miss a lot of information. It's likely just a limitation of Reshade and/or ENB. So like for example, when people are showcasing graphics mods with SSR, such as with GTA V, if they're driving a car and are on a rain puddle, you could see the underside of the car is missing (you can see through it), among other things like that.

One of the main things for me especially is RTGI. If you use RTGI, it seems to suck sometimes. RTGI (Ray-Traced Global Illumination) for any game via Reshade just isn't good. Again, it misses a lot of information because it's only on-screen stuff. So if you had a light source off-screen, it doesn't care about that. You could look at a wall and it's bright as shit and everything else around it is lit up by it. Look at it from a different angle and now suddenly everything looks unlit. A video from kliksphilip when he was using an RTGI thing for Half-Life 2 showed this example well. He looked at a wall in Nova Prospect and in some angles the wall was bright and the light bounced off it onto the other props, but if he turned his camera it wasn't bright anymore, and appeared unlit.

Even if I had an RTX PC, it's this sort of stuff that steers me away from graphics mods and things like that. Using only what's on-screen can cause some strangeness in most cases. Sometimes it's blatantly obvious, other times you need a keen eye to notice. And it got me wondering if it's possible for Reshade to use data that isn't on-screen in some way or another. RTGI mods would probably work way better in this aspect, as it would take almost everything into account and provide a much better look.
 

Short answer to the question in the headline: No.

Long answer: To my understanding it could be possible to code a plugin for Reshade 5.x that is able to pull information from off-screen but that is completely dependant on the game or game engine how to do it, if it's even possible. I can imagine that with Bethesda's engine it could be possible.

Regardless of all that, then you need to write a shader that can make use of that exposed info somehow.

I'm no expert, but the only way I think that's possible would be to set the game to render at a very high FOV which would have a much larger screenspace and then have the shader "fix" the image (yet still have access to the larger screenspace).

AFAIK as I know, no one has done this in a shader yet. Sounds costly. Text and UI elements would be cut off and warped.  The math involved would be beyond me.

Technically, the short answer to this question is no. However, the long answer (and the reason why effects like SSAO and RTGI are possible) is that limited information about world geometry can be pulled from the depth buffer by accessing it with negative Z values. The extent to which this works depends entirely on how much information the game stores about areas that are outside the player's current field of view.

That's similar to my idea -- but MUCH more clever.  Neato.