PBR Experiments - Questions (Mostly) about Reflection Probes and Mirrors

[Love Zhaoying]

I finally reached a "peak achievement" (stuff mostly seems to work), with "peak questions" (as in, WTH!?) about Reflection Probes / Mirrors.  So, I am starting this thread to a) show what I am trying to do, and b) ask questions about the things I do not understand and issues I am seeing.

Note:  I am NOT creating "PBR Materials" for this.  Feel free to add anything related to PBR Materials to this thread, but my questions are really about my experience so far with Reflection Probes and Mirrors.

My goal for this was to use new Lighting techniques that only came with PBR Reflection Probes, including Mirrors, to light a "dark cave" which I already have. (I do not plan to change any of the cave textures with PBR materials / textures, since the cave is "no mod" except for tinting.)

At the bottom is a picture of my initial progress, and some screen shots of various settings.

Thanks in advance, 

Love

P.S. Thanks so far to @Istelathis, @arton Rotaru, @Inara Pey's article, and a video LL featured about creating Mirrors: https://www.youtube.com/watch?v=kbdMtduYWag

 

My machine specs / "Help->About":

CPU: 12th Gen Intel(R) Core(TM) i5-12500H (3110.4 MHz)

Memory: 16089 MB

OS Version: Microsoft Windows 10/11 64-bit (Build 22621.2861)

Graphics Card Vendor: NVIDIA Corporation

Graphics Card: NVIDIA GeForce RTX 3050 Ti Laptop GPU/PCIe/SSE2

Windows Graphics Driver Version: 30.0.15.1274

OpenGL Version: 4.6.0 NVIDIA 512.74

Questions / Comments / Issues

1. I believe that I had to change settings to "Ultra" for Mirrors to work.  (Or, it was at least between "High" and "Ultra".)

 

Is this expected?  

 

2.  The "first Reflection Probe" (not the mirror, the one I am sitting in) stopped working after some changes, and nothing but a PC reboot seemed to change it.  I have not reproduced this issue yet, although it seems changing some graphic setting to get the RP Mirror working probably did it.

 

Has anyone else seen issues where a Reflection Probe stopped "working" with no explanation, only to "start working again" (whether after a reboot or some other change)?

 

3. Which of the "Advanced" settings for "Screen Space Reflections" work (or work best) for Mirrors?

 

(See picture)

 

I did not see this in the tutorial I watched (or posts that I read), but I believe that had to change my setting for "Reflection Detail" and/or "Reflection Coverate"  in order to get the Probe to show my avatar properly. 

 

Later, it was unclear whether this setting was required or if I had "kicked" something else to get it to work.

 

4. Is it widely known / always true that "snapshots" do not work to capture mirror reflections?

 

I saw @Istelathispost about this also, and it was true for me too - I had to use a "screen capture" to get any reflections of my avatar.

 

5. Why does my Cave mirror (which is "horizontal" like a "reflection pool") show several bright lights in it? The picture shows two, but there are at least 3.

 

Is this the Sun and Moon?

 

Is it caused by the "other" Reflection Probe in the scene (although I thought that I had moved my other Probe to rule that out).

 

6. I have seen several posts that it is hard to select Reflection Probes. 

 

Note that in the Official viewer, you can enable selecting (and seeing their "volume") under Build Options. 

 

However, I noticed these Options get reset when you relog into Second Life!  Is this JIRA-worthy, and did someone already post a JIRA on it?

 

7. How many maximum Reflection Probes can we have in the same area?  (I realize this is probably in a tutorial someplace.)

 

8. Which of the EEP settings seem to most help with showing RP's?  

 

My original goal was to use only the "Sunset" lighting (presumably with EEP, not the standard "preset") for the effects I wanted to achieve.

 

It seems like when I tweak the EEP settings, sometimes the "first Reflection Probe" (the one I am sitting within) works, and sometimes it does not work.

 

Do the "Glow" settings make a difference?  Note that if I change some settings a bit too much, the Reflection Probe seems to stop working (possibly even until a "relog").

 

Oops, I noticed that the picture was taken using "default" settings instead of Sunset or my "experimental" settings.  

 

See picture for only EEP settings I changed, should I also change others?

 

 

Picture showing both a) Reflection Probe that I am partially "in" (like a "spotlight" on the right side of my torso), and b) Mirror below me:

 

 

Picture showing my current "Screen Space Reflection" settings:

 

Picture showing the only EEP settings which I changed:

Edited December 28, 2023 by Love Zhaoying

[arton Rotaru]

That's a lot of questions, but to address the most obvious one.

This initial release of the GLTF PBR viewer is not about mirrors. Actually the Developer is quite unhappy when we do "mirrors" with the viewer because they aren't working as a mirror should work, and hence people will complain that the "mirror" they bought doesn't work as they would expect a mirror to work.

What we have are reflections from the cubemap snapshots of the reflection probes, plus screen space reflections. SSR does only work on very flat angles. They have been added initially to be used on the Linden water.

You only need reflection probes in your cave to cover the volume inside. The water thingy should be just a reflective surface, but not a probe on it's own.

There is an open Jira about probes stop working when the Personal Lighting floater is open and selecting a sky preset. There is a trick to get the Probes back, but a relog will do as well.

The Selecting Reflection Probes option is per session only. That's by design.

The bright reflection you see on the shiny surface is from local light sources. No way to get rid of those.

The viewer does render up to 256 reflection probes at the same time. The default is set 128.

Glow does not add to the lighting of a probe. Fullbright does though.

I noticed that the snapshot feature doesn't catch the screenspace reflections. That might be a bug. Perhaps a limitation? Jira worthy indeed.

Edited December 28, 2023 by arton Rotaru

[Love Zhaoying]

Thanks for all your replies! I will just focus on a few for now, and digest the others as time allows.

38 minutes ago, arton Rotaru said:

You only need reflection probes in your cave to cover the volume inside. The water thingy should be just a reflective surface, but not a probe on it's own.

I am pretty sure that I do not understand your answer; here I try to explain a little better why I am using two reflection probes:

1. I am using the "first" reflection probe that I am "sitting in" to purposefully light only part of my avatar; this is a similar use for the probe that I saw in other's pictures. (I am literally sitting inside the probe.)  The point of this effect is to be sitting partly inside a light that appears to be shining inside the cave entrance.

2. The water thingy is intended to be the only "mirror" in the scene.  It has the "second" reflection probe inside of it (just like a normal PBR "mirror").  Since I'm trying for the "true reflection" and not just a water effect, how would you suggest doing that differently? 

Are you saying that I just need one large probe to fill the cave (then use the reflection for water)?  If so, how would I accomplish the effect in #1 (sitting partly inside a light)? Note that before I got the "first" probe to work as #1 above, I did use a projector to achieve a similar effect as #1 (but then did not need the projector anymore).

39 minutes ago, arton Rotaru said:

The bright reflection you see on the shiny surface is from local light sources. No way to get rid of those.

Since I don't have any local light sources in the cave, does this mean there are other local light sources nearby (outside the cave) that are showing up? 

I can double-check that none of the "torches" are "local lights" (I tried especially hard to make everything dark by tinting the entire cave, and checking "local light" OFF anywhere I found it.)

 

[arton Rotaru]

Yeah, the "mirror" is just a reflective surface. It's just a reflective surface with PBR materials as well. If the water is within the probe you are sitting in, thats all that is needed.
You could indeed rez another reflection probe to cover the water, but the water itself should never be the probe.

If you are trying to achieve certain things for taking photos, it's up to you to get the desired effect indeed.

The bright reflection may well be the sun then, which is basically a local light source as well, just a very bright one.

Edited December 28, 2023 by arton Rotaru

[Love Zhaoying]

3 minutes ago, arton Rotaru said:

The bright reflection may well be the sun then, which is basically a local light source as well, just a very bright one.

I thought of that, and that perhaps the Sun + Moon account for 2 of the bright reflections, but doesn't explain the 3rd bright reflection (plus others you can't see all at once). I suspect that some of this is because I'm using a "horizontal" mirror, which I didn't see used except in possibly 1 other user's picture,

7 minutes ago, arton Rotaru said:

If you are trying to achieve certain things for taking photos, it's up to you to get the desired effect indeed.

On the surface (no pun intended), I take this advice to mean "try different things" such as: use single probe plus projector for the other effect, and different EEP settings to try and reduce the effect of the bright reflections.

I think the initial "catch" I see if that if I fill the cave with light, my avatar will be fully bathed in light - and a projector can't cancel that out. Possibly just do away with the "first" probe and use a projector for lighting my avatar, will be a first step.

All that being said, the current overall effect is pretty much what I wanted (except the bright reflections in the "water").

 

[Jenna Huntsman]

That bright flare could be the spotlight that's illuminating your avatar - you need to be careful with the light's FOV value to avoid this. (The projector texture isn't always sampled when rendering lights, as this would be much slower than looking at the light's overall parameters).

Note that light flares aren't able to be removed (because, the flare is created by the light a lamp emits, not based on if the lamp itself is visible), but careful tuning of light parameters can avoid unwanted flares.

If the flare is from the sun (as Arton suggests), then enabling shadows should resolve the issue.

In terms of EEP for PBR, I have some pointers on my wiki page for some rules-of-thumb: https://wiki.secondlife.com/wiki/User:Jenna_Huntsman#PBR

In addition to what Arton said in regards to glow and fullbright, emissive surfaces (either Blinn-Phong or PBR) will contribute to lighting. As a rule of thumb though, any surface that emits light should also have some amount of glow added (because, glow is an optical effect caused by the emission of light)

 

Edited December 29, 2023 by Jenna Huntsman

[Love Zhaoying]

12 minutes ago, Jenna Huntsman said:

That bright flare could be the spotlight that's illuminating your avatar

I'm not actually using a spotlight on my avatar in that picture.  My avatar is sitting partially inside a reflection probe, and the light is only coming from outside the cave (or whatever PBR is using to provide the light).  I don't have any local lights setup, etc. for that reflection probe.

I do HAVE a "spotlight" but am not using it because the effect for using the reflection probe was better / what I really wanted.  The "spotlight" had 3 "modes" to test with - on, projector (which created a similar effect), and off - and was turned completely off in that picture.

15 minutes ago, Jenna Huntsman said:

If the flare is from the sun (as Arton suggests), then enabling shadows should resolve the issue.

I'll take a look at that - I thought shadows are enabled, but turning certain features on/off could have somehow switched shadows "off".  I'm glad you mentioned "shadows", as eventually that is something I want to add to the "scene".

 

16 minutes ago, Jenna Huntsman said:

In terms of EEP for PBR, I have some pointers on my wiki page for some rules-of-thumb: https://wiki.secondlife.com/wiki/User:Jenna_Huntsman#PBR

Thanks, another resource!! 

17 minutes ago, Jenna Huntsman said:

In addition to what Arton said in regards to glow and fullbright, emissive surfaces (either Blinn-Phong or PBR) will contribute to lighting. As a rule of thumb though, any surface that emits light should also have some amount of glow added (because, glow is an optical effect caused by the emission of light)

Hmm..I may be misunderstanding "emissive surfaces" here.  I don't have anything intentionally emitting light.  By "any surface that emits light should also have some amount of glow added" - are you referring to the EEP "Glow" setting, or something with the surfaces themselves?

Thanks!

 

[Jenna Huntsman]

27 minutes ago, Love Zhaoying said:

Hmm..I may be misunderstanding "emissive surfaces" here.  I don't have anything intentionally emitting light.  By "any surface that emits light should also have some amount of glow added" - are you referring to the EEP "Glow" setting, or something with the surfaces themselves?

Emissive surfaces are surfaces which have variable amounts of unlit parts - i.e. a better (more controllable) fullbright (fullbright essentially makes an entire surface emissive at 100% intensity) - For Blinn-Phong materials, this means the alpha mode is set to "Emissive mask", or for PBR materials, see here: https://wiki.secondlife.com/wiki/PBR_Materials#Emissive_.5B_RGB_.5D

The "Glow" setting I refer to is the glow parameter seen in the Texture panel of the build floater (i.e. a property of the prim).

Here's an example of a light source with glow:

and without:

Edited December 29, 2023 by Jenna Huntsman

[Love Zhaoying]

1 minute ago, Jenna Huntsman said:

Emissive surfaces are surfaces which have variable amounts of unlit parts - i.e. a better (more controllable) fullbright (fullbright essentially makes an entire surface emissive at 100% intensity) - For Blinn-Phong materials, this means the alpha mode is set to "Emissive mask", or for PBR materials, see here: https://wiki.secondlife.com/wiki/PBR_Materials#Emissive_.5B_RGB_.5D

Is there any way to tell if surfaces are emissive for existing, non-PBR materials?  This is mostly a "no-mod" build except that I can tint surfaces / turn off local lights, etc.; I made it "dark" by changing the tint color for all the objects from "white" to a "dark grey".  (Let me know if that means "yes, it means they are emissive".)

3 minutes ago, Jenna Huntsman said:

The "Glow" setting I refer to is the glow parameter seen in the Texture panel of the build floater (i.e. a property of the prim).

Thanks! I already was able to edit the build to make sure there are no "lights", I can go back to check for "glow".

If all this means "this cavern can't be used due to the materials being emissive", then I can check other caverns to see if they are "darker" / don't have emissive surfaces, etc.

[arton Rotaru]

3 hours ago, Love Zhaoying said:

If all this means "this cavern can't be used due to the materials being emissive", then I can check other caverns to see if they are "darker" / don't have emissive surfaces, etc.

It would be super unusual if such rocks would be emissive. You would have noticed it the past already. So your cavern should be as good as any.

[Love Zhaoying]

Update: I performed several experiments - turned off shadows, changed textures and different settings in EEP, and the "bright reflections" still persisted with any changes I made.

That shall remain a mystery, and I will assume they are due to the fact it is a "horizontal mirror" for now.

I will still follow-up on other suggestions made, such as "just use 1 reflection probe".

ETA: I also did not see anything set to "glow".

 

Edited December 29, 2023 by Love Zhaoying

[Jenna Huntsman]

7 hours ago, Love Zhaoying said:

Is there any way to tell if surfaces are emissive for existing, non-PBR materials?  This is mostly a "no-mod" build except that I can tint surfaces / turn off local lights, etc.; I made it "dark" by changing the tint color for all the objects from "white" to a "dark grey".  (Let me know if that means "yes, it means they are emissive".)

Generally, you'd already know, as the most common way (by far) to make a surface emissive is to make it fullbright. So, if it's not fullbright, it's very unlikely it's emissive.

[Love Zhaoying]

Also posted in "How does your SL look today?".

I finally got LoveX in a PBR photo with me using a Reflection Probe..then I forgot you can only capture mirrors with "screen shots"! (Next time..)  LoveX was using Mobile, the hardest part was for her to "touch" the thing she needed to sit on.

[Love Zhaoying]

Finally a picture WITH LoveX WITH the Reflection (a screenshot).

Also posted in, "What does your SL look like today?"

 

Edited January 9 by Love Zhaoying

[Love Zhaoying]

On 12/29/2023 at 8:01 AM, Jenna Huntsman said:

The "Glow" setting I refer to is the glow parameter seen in the Texture panel of the build floater (i.e. a property of the prim).

Yes, I checked everything and nothing is set to Glow, so..I think the bright lights in the Reflection Probe "mirror" are because it is "horizontal" (parallel to the ground).