Reflection Probes

[uncut osprey]

Hi guys, after practising about better visuals in unity I got some new questions.

Question 1:
I understood how a reflection probe works but there is a problem. In a complicated facility, how should I place these probes? I mean I placed a reflection probe to the elevator because it was separated and small. But should I separate the facility to place reflection probes. What is the key of placing them?

Question 2:
In elevator, the ceiling outside of the elevator reflecting the light inside the elevator even there is a wall between them. How can I stop that?

Question 2 solved immediately sorry :D I forgot to change spotlight's shadow type.

Question 1 still active.

[azure tiger]

Question 1 depends on mainly on how accurate you need your reflections to be
If every room is similar, and you don't have purely mirror sheen materials, even just one reflection cubemap for the whole scene may be enough

As long as it's taken from a spot that doesn't stand out

You should start with that and then place local probes in areas that need something more accurate

[uncut osprey]

Oh I understood, I thought they should be inside of the walls but with a huge probe box capturing all the facility is good to go? And then If I dislike somewhere I will separate there and add another reflection probe. If I clearly understand.

[azure tiger]

The probe's position is the point it will capture from when baked (or if realtime) so at that moment it can't be "inside the walls"
But after that it doesn't technically matter where it is
The box is not the range it will capture, but the mesh renderers it'll affect with its captured reflections

The scene always has one global reflection probe that's captured just from the sky material

It can be used alternatively from a separate "global" reflection probe component, but makes no difference for the resulting visuals

If a global probe is not accurate enough for a particular room, a local probe with a higher priority and the bounding box covering just that room would improve it
With local per room probes you can also utilize box projection for even more accuracy

If lighting changes drastically in a room, a baked reflection probe would not be accurate
If too inaccurate you could consider a realtime probe (typically updated only when necessary) or multiple baked probes you swap between to match the changing lighting conditions

[uncut osprey]

Oh I see, there is some rooms has lights that changing by time. I will put realtime reflection probes and baked lightmap swapping system in that room and the rest of the facility will be captured by a baked reflection probe. Is there a problem if their capture boxes overlap?

I think you mentioned it by "higher priority"

[azure tiger]

Only one reflection probe can be in effect, based on priority, aside from blending by Blend Distance

Realtime reflection probes are really expensive so you would use them as a last resort

Even if not updated every frame they can be a bit prohibitive, but depends on performance conditions

Your first option would be to use a baked probe but exclude any dynamic lights from the bake
Likely realtime direct reflections from the dynamic lights combined with baked reflections from static light sources will look good enough

[uncut osprey]

Okay I can use baked reflection probe swapping system too but If I travel in that room with flashlight is it going to consider it to reflect?

[azure tiger]

But then there will be no indirect reflections from objects lit by your direct light sources

[azure tiger]

Realtime lights have direct specular reflections on materials, but if the probe is pre-baked, objects lit by the flashlight won't be visible in reflections

That's usually not a problem but with fully metallic materials that means they can be much darker than expected if the room has no static lights to get indirect reflections from, as metals are only lit by specular reflections

It sounds more complicated than it is, as long as you understand the difference of diffuse and specular reflections, and realtime versus baked probe reflections

If you have metals and mostly dynamic lighting, you could still use a baked probe for reflections to prevent the metals from looking totally black outside of direct light, but then there's a bit of a sheen to everything even when it's supposed to be dark

Most often games go with the latter option

[uncut osprey]

Allright I researched a bit and I will try some cases by example scenes. Thank you for the information :)

[uncut osprey]

This is before I bake the reflection probe captures all the facility

and this is after :D

I think I am missing something

lights are set to static, objects are set to contribute gi, light settings set to baked

what is the problem?

It it getting more complicated

As you see in the console log it says there is lots of light shadows so I changed light sources to baked mode but now it looks trash after I bake reflection probes.

[azure tiger]

Can you show the reflection probe's properties and preview as well

I think the difference of before and after is mostly that you now are using baked lights instead of realtime in general, not so much about the reflection probes specifically

[uncut osprey]

Actually the room with electronic devices had lights that always baked I did not changed their mode

And also elevator still looks good actually getting better after bake

[uncut osprey]

this is the properties of it

[uncut osprey]

Okay so I realized that meshes in the facility has generate ligthmap uv toggle off

I set it on and it get better but still not enough as pre-baked

elevator pre-baked

elevator baked

[azure tiger]

Now this looks more like the expected difference of realtime vs baked lighting
But yet without accurate specular from reflection probes

[uncut osprey]

I researched a bit and learned that reflection probes aren't storing lights is it rigth? And I find out that there is something named specular probes do you know what it is I could not find much sources about it

It is a script that provides light source storage for reflection probes

[azure tiger]

https://forum.unity.com/threads/lightmapping-troubleshooting-guide.1340936/
c.5

They're objects, typically just meshes with an emissive material to represent the light source that is only visible to the reflection probe

Scripts can be used to place them automatically but they're not strictly necessary