DFAO Specular Occlusion - Alireza's Art Blog

Maximum-Dev

Hello Polycounters,

I have recently received a lot of requests for tips, tutorials and tricks here in forums and on UE4 FB group regarding the work I do, some of which belong to the game I'm creating with some of my friends [Our Ghosts of War]. I considered creating a blog but for the sake of better exposure I decided to just create a thread here. Anytime I have something to share I'll be posting in this thread and I'll be honored to answer your questions (if any).

I'm currently putting together a post about my lighting approach. If you have any requests please let me know.

Thank you.

Maximum-Dev

Tip 01 - How much light am I casting on my world?

PBR material systems introduce the need for physical lights. By that I mean we should have an idea of how much light we are casting on our materials otherwise we’re breaking the point of PBR which is achieving a more realistic look.

Unfortunately the Sun in UE4 doesn’t have any physical units such as Lux so you wouldn’t really know how much light you’re casting on your world. There are some ways to calculate this but in the end you’re not gonna have a result as pleasant as you’d have with a physical light. Now I’m gonna give you some values that I’ve found most helpful in my cases. For overcast lighting all that’s needed is a good cloudy Skydome and a Skylight intensity of 1. For a Sunny/Cloudy day a value of 3.14 as Sun intensity works well and the Skylight intensity should be reduced a little in order to maintain a good contrast between light and shadow. If we have a little less clouds and more Sun a value of 4-5 for Sun would be ideal. For those burning deserts with a violent Sun a value of 7 does wonders.

But I strongly advice everyone not to go beyond 7 as it’s going to start making your materials look worse. It kills the all the surface detail specially details in roughness are already mostly lost at this light intensity. People often go over an intensity of 10-12 to get the look they want but that’s a mistake. Either texture’s don’t have the correct luminance (they were darker than they should’ve been) or you’re a victim of UE4’s Tonemapper. UE4’s Tonemapper clamps the whites so much that initially you’re having a washed out image. To prevent that you have to have a great knowledge about tonemapper to tweak the settings very carefully while maintaining both neat white and black levels, unfortunately I'm not much of a good lighter nor I have a great knowledge about Tonemapper settings. (It's easy to tweak them and get the desired look, but it won't be correct for all scenes if it's not done properly) - (praising the lighters at DICE for their work), I choose a simpler solution here.

1. Create an empty level.
2. Remove pre-baked lighting.
3. Add two cubes, one pure black and one pure white: BaseColor 0, Specular 0, Roughness 1 and BaseColor 1, Specular 0, Roughness 1.
4. Add a directional light, set intensity value to 3.1415 (This value let's you see the true surface color) more information here.
5. Add a Post Processing Volume, set Min and Max Exposure to 1.
6. PrintScreen, paste into Photoshop.



When I color pick the left cube the value is almost 0,0,0 but when I color pick the right cube the value is 209,209,209. I want my right cube to be somewhere between 245,245,245 to 255,255,255 while my left cube stays at 0,0,0 without having to touch the Tonemapper. What I do is to simply add a Brightness/Contrast adjustment layer and increase the brightness until the right cube reads the value I want when I color pick it. The left cube would be left at 0,0,0 just like I wanted. Now I can apply this brightness adjustment to the Color Lookup Table and save it out, load it in my Post Processing Volume and voila! My whites are back.



Now I'm using this Color Lookup Table for all my works. It's not perfect, nor correct, but I'll be keep doing this until I master my Tonemapping knowledge.

Example of this Color Lookup Table with Directional Light intensity of 3.14.



Thanks for reading!

Edit:
Added missed line before taking PrintScreen: 5. Add a Post Processing Volume, set Min and Max Exposure to 1.

Maximum-Dev

Tip 02 - PBR materials needs baked shadows and specular maps and here's why.

It doesn’t matter if it’s Megascans or what, once imported in game engine you get average looking materials. 
In Megascans library you’re looking at renders on surfaces with tons of triangles. Every tiny detail is in 3D and it receives shadows plus it casts shadow as well as generating AO. But once you import materials in a game engine it’s a different story. Your surfaces in game engines are low poly, your landscape surface consists of 2 triangles per 1 square meter. There are ways to overcome this. There is a false belief among some artists which is that in a PBR engine a none metal material doesn’t need a Specular map. Another false belief is that Albedo should be free of any shadows.

Your Albedo should be free of shadows, but not any shadows. Very small scale shadows or micro shadows are something that game engines can’t take care of and these shadows need to be present on the Albedo map. To get a better knowledge of what I mean by micro shadows take a look at the image below.



Such shadows if removed from the Albedo, would not be reconstructed by the render engine no matter if you use a separate AO map or not. AO maps have no effect when the surface is lit and they only work if thesurface is covered in shadows so you really gotta keep those micro shadows in your albedo maps. Some people tend to remove those shadows then use a separate Cavity map and multiply that by Albedo in the material editor, I don’t get the point of removing them and then adding them back with the additional cost of an extra Cavity map.

Now those micro shadows represent cracks or holes on the surface and basically those cracks or holes look dark because there’s not much light being reflected from there to your eyes. But wait a second, having a constant value as specular means the entire surface is reflecting light equally which in case of the example above is incorrect behavior as there’s very little light coming from those cracks and holes to your eyes so the specular value for the cracks and holes should be less than the flat areas.

I don’t go for a separate Specular map though as that’s unnecessary memory cost. But I can easily drive a specular map from the Albedo itself by running it through a clamp node with a min value of 0 and a max value of 0.5. (0.5 is the specular for most non metals). To further introduce some more variation on the produced specular map and make the surface look more interesting we can run it through a Power node to make it more contrasty before running it through the clamp node. This makes the surfaces look more real and even behave more correctly as now the cracks and holes aren’t reflecting light as much as the flat surfaces.

Here are some pictures showing the difference between a vanilla rock material and the material plus the calculations I mentioned above. You see the second picture shows much better surface representation.




And here is a comparison while looking at the Specular buffer.




That's it for this post.

Edit: It's also nice to re-read the Specular section here: https://docs.unrealengine.com/latest/INT/Engine/Rendering/Materials/PhysicallyBased/

Maximum-Dev

Tip 03 - Increasing quality and performance of natural outdoors.

See the pictures in full res to see the differences better.

1. Instead of having a lot of leaves cards on your tree, try to have as much less cards, but larger in size so you can have much more leaves on your cards which ends up filling the trees with much less tris.

2. When creating your leaves cards try to have as less empty space as possible, it’s fine to spend more tris on a card but reduse the transparent spaces because in the end overdraw costs more than trinagle count.

3. When using a directional light for an outdoor environment you can set the dynamic shadow cascades to 1. This will instantly release a lot of frames.

4. Use DFAO with a min occlusion value around 0.15. In case 0.15 makes it too dark for you the problem is with your lighting and/or textures not being calibrated to PBR friendly values. If you see ultra dark spots anywhere on a mesh you need to increase the Distance Field Resolution Scale for that mesh. Don't tend to increase the Min Occlusion value to make the errors less apparent.

5. In case you’re using a billboard for your trees, try to tile a very rough and noisy normal map on it. At far, that noisy normal map on the billboard will break the flat look. (And don’t forget to increase the Opacity Mask Clip Value for the billboards too. Compare the before/after below (see in full res).

6. If you have noticed, usually your foliages look not so well when you’re not close to them. And that’s because of the mipmapping. What happens is that when the texture is mipmapped you lose the full resolution and thus your alpha or opacity is blurred. That little blur results in losing all those tiny while holes and lines and therefore you don’t get to see anything from behind the mesh. This can be solved by increasing the Opacity Mask Clip Value. As you can see in my pictures the trees look very noisy, full of holes, you can easily see the sky behind the leaves and that’s what makes it look realistic.

Let's compare the results of Opacity Mask Clip Value of default 0.3 vs. 0.5.

7. Set your SSAO intensity to 1, Quality to 100, Fade out Distance to maximum.

8. Check “Generate Distance Field as if TwoSided” on your foliage meshes and their LODs. This will leave fewer artifacts in DFAO generated on your meshes.

9. Increase your normal map strength on grasses/leaves a lot! This will make your flat planes look directional. Plug the normal map to the A pin of a Multiply node, plug a 3Vector into the B pin, set the 3Vector values to 1,1,0.2 and that should do it.

Here's a comparison, you clearly feel the flat cards in the first picture.




10. Profit.

Maximum-Dev

Hey everyone,

There was a small discussion on UE4 FB group regarding using Albedo to create a Specular map. I think this deserves more clarification.

The intensity multiplier on my rock specular in the picture I posted earlier was actually low, my apologies for that. But increasing it can produce results pretty close to what an actual cavity multiplied by 0.5 does. For us I'm only doing this to save on an extra cavity map. To be honest the Megascan Albedos aren't completely shadow free so running the albedo through a Power and Multiply and finally a Clamp with min 0 max 0.5 and a little tweaking can let you amplify those shadows and use them for Spec. Here's the Spec Buffer view: 

If you multiply a cavity map by 0.5 you get almost similar results to what you're seeing above. It's not 100% the same when you compare it side by side on your screen close up. And not using a separate cavity map is a great memory saving by itself so this is what I decided to do for our game and other side projects.

Maximum-Dev

Tip 04 - What grass shapes work better?

I have experimented with lots of grass meshes and lots of grass fields. One of the nicest ones for me (in terms of forms) is the one below. My goal was to create a low poly grass field that runs well and has some interesting height variations to it. So I made a lot of grass meshes and I'm gonna show the two winner meshes below.





Above is the medium grass. It's a single plane instanced 6 times. The texture that I'm using on the mesh is actually very straight grass blades material from Megascans and I couldn't really find my desired texture on the  library so in order to make it look more like bent grass patches I've rotated the two instances on each end outwards. Doing this I realized the curve that's created on the top (as you're seeing in the front view) adds a ton to the look of the grass field when I'm looking at it in UE4. That curve makes it transit smoothly to the other small grass. The 3 other instanced planes are doing a great job making it look more 3D from perspectives other than front. Basically X grass as you see in the top view.

This is the mesh for the small grass:



I have been doing a lot of variations but in the end I went with this setup to have a more uniform distribution since this is actually small grass and is only there so when you look down you see some stuff going on around you, not dense at all. If you're wondering why the square shape, I'll cover that some time later. So the two grass meshes aside, I'm mostly relying on the grass material that's on the landscape surface. Here's me looking down:



When looking at a large grass field all grass meshes get culled at some distance. I did endure a lot of pain in order to make the transition from grass meshes to landscape grass material less apparent when the meshes are culled. I'll cover this at a later day as well.

Note: I'm in no way an expert in anything and in no position to try to lecture anyone. I'm sharing what I found to be the most helpful in my cases and if anything in this thread helps anyone, I'll be glad of it.

Thanks for reading.

Maximum-Dev

Tip 05 - Grass is shinier on the other side and it needs to be taken care of!

I looked around A LOT. Spent a lot of time trying to figure out a solution. This is just another flaw of the PBR in my opinion. We have translated the real world surface rules into game engines without having the power to have the same real world geometries with trillions of triangles to apply these rules to. Looking around I noticed the Cryengine community had the same problem but Crytek has already dealt with it. This slide gave me some clues.



Here's a very very simple grass material:



And this is how it looks like on the landscape surface:



But as the sun starts to rotate, you start to have reflection problem. No where in the world a grassy ground looks like this:



So I reconstructed a Specular map using the Albedo, as I have explained in Tip 02 to prevent 100% of the surface from reflecting light equally. This is how it looks like in the material editor:



And this is how it looks like on the landscape, but it's still way off...



To reduce the specular gain I went ahead and used the Fresnel node to mask out the area where the specular is gaining, and reduced the specular intensity for those areas from 1 to 0.33. This is how it looks like in the material editor:



And finally, this is how it looks like on the landscape surface:



But still, it does look off somehow. You notice in the middle the reflection is stronger. If we had grass meshes here, when they are culled it'd look too obvious that they are disappearing and breaks the immersion into bits. Next time I'll cover how I went around this issue.

For demonstration I have used a grass material. But any material that's rough and has a lot of volumes to it in real life like grass does, it can greatly benefits from this method.

Thank you for reading!

Maximum-Dev

Hi guys,

With the release of 4.15 the LUT included in Tip 01 no longer gives correct results due to the tonemapper changes. I have created a new LUT that works correctly with 4.15 unclampes the whites. Left is with LUT, right is without.



I realized using the Levels modifier gives more accurate results over Brightness modifier. You can grab the LUT  here.

Sajeet

Thank you for these tips m8! Keep them coming. And thx for the LUT

Steppenwolf

There are a few more tricks for the specular grass problem. You can use macro masks in the material for distance specular or roughness variation and you can use the composite texture feature to create roughness variation. https://docs.unrealengine.com/latest/INT/Engine/Content/Types/Textures/Composite/

Maximum-Dev

Tip 06 - Make that material look good.

Hi everyone,

I had some requests for a tutorial from people regarding their Megascans materials not looking correct inside UE4, and I thought I'd do some tests here, mostly doing different setups and making comparisons in order to find out what material setup works best and is most cost efficient. I did 7 tests and I'm sharing the results below and I hope it helps. Please note that the number of each test corresponds with the numbers seen on the images. Half the surface is covered in shadows to see the changes both under light and shadow.

1. Albedo + Normal + Roughness + Specular 0.5

With this setup you see missing AO on the entire surface, as well as an unpleasant uniform reflection.

2. Albedo + Normal + Roughness + Specular 0.5 + AO

We add the AO map to the AO input. You see there are some very subtle AO introduced, but only in the shadowed part. The lit part on both sides remains without AO and fine shadows. Both sides still have uniform reflection as well.

3. Albedo + Normal + Roughness + Specular 0.5 + AO + AO Multiplied on Albedo

We multiply the AO on Albedo. This introduces fine shadows to the surfaces and the lit areas start to look nice. But since AO is only affective in the shadowed parts, it gets coupled with the AO that's multiplied on Albedo and creates over occlusion on the shadowed parts.

4. Albedo + Normal + Roughness + Specular 0.5 + AO Multiplied on Albedo

We originally added the AO map to the AO input in order to have fine shadows on our surface, but it resulted in over occlusion when we multiplied the AO on Albedo. Simply disconnecting the AO map from the AO input gives us consistent fine shadows on both lit and shadowed areas. Now we have those fine shadows sorted out, but the unpleasant uniform reflection is still there.

5. Albedo + Normal + Roughness + Specular 0.5 Multiplied by Cavity + AO Multiplied on Albedo

We multiply the Cavity map with 0.5 and plug it into the Specular input. The dark parts in the Cavity map will reduce the 0.5 value (where we have fine shadows and shouldn't receive as much light as we do from the rest of the surface) and this breaks up the uniform reflection. The result looks nice now however, there's one big issue. We are using too many texture maps for one material (5 textures). Now we look into reducing that.

6. Albedo + Normal + Roughness + Specular 0.5 Multiplied by AO + AO Multiplied on Albedo

We take out Cavity and instead we multiply the AO map with 0.5 and plug it into the Specular input. The result isn't 1:1 with a Cavity map as you see in the Specular Buffer.

7. Albedo + Normal + Roughness + AO Multiplied by itself then multiplied on 0.5  for Specular + AO Multiplied on Albedo

The result looks acceptable now, and when in Lit mode, the difference is subtle that people don't notice it in game, yet we have reduced our texture count from 5 to 4 which is a big gain.

To further reduce the texture count we can put our Roughness into the Normal map Blue channel, and put the AO into Normal map Alpha channel. Having done this the compression type on the normal map needs to be changed from "Normal" to "Masks". The normal map Blue channel is reconstructed inside the material editor. Our texture count is reduced from 5 to 2.

And here is a comparison between 1 and 7.

Enjoy Megascanning and thanks for reading!

KHM3dia

You mentioned the fact that placing the Roughness and Ao in the Normal map and changing it to masks. Would that cause any quality loss since the compression isnt set to normal? Although the blue channel doesnt get used, I suppose youre method should work fine. From my experience ive always packed Roughness, Height/Metallic, AO and possible Cavity in the Alpha and used parameters if i want to use certain channels but also use scalar multipliers to controls the strength. 

Wenceslaus

Hello!
Thanks a lot for all this, it is really valuable to me.

Does the "AO multiplied on Abledo" means you multiply both into the colour input? I wonder if it could be done in Photoshop to save one operation (if that will have any effect).

Maximum-Dev

KHM3dia said:

You mentioned the fact that placing the Roughness and Ao in the Normal map and changing it to masks. Would that cause any quality loss since the compression isnt set to normal? Although the blue channel doesnt get used, I suppose youre method should work fine. From my experience ive always packed Roughness, Height/Metallic, AO and possible Cavity in the Alpha and used parameters if i want to use certain channels but also use scalar multipliers to controls the strength. 

Yes there is a slight quality loss when setting the compression type to Masks, but as long as the surface isn't wet/glossy it's quite unnoticeable. You can channel pack your AO, Metallic, Roughness, Height into a single RGBA but usually materials do not need a Metallic map as they have nothing metallic in them, Roughness can be generated inside the material editor from an albedo, AO can be just baked on the Albedo instead of multiplying it on Albedo inside material editor, Cavity can be just ignored as AO can produce pretty close results, and you'll be left with only a heightmap, which can be put in Normal map blue channel. That's my approach mostly. And please keep in mind we're talking about organic materials such as Ground, Wood, etc. and I don't recommend this for things such as Weapons, Characters and such other assets.

To reconstruct normal map's blue channel:

Maximum-Dev

Wenceslaus said:

Hello!
Thanks a lot for all this, it is really valuable to me.

Does the "AO multiplied on Abledo" means you multiply both into the colour input? I wonder if it could be done in Photoshop to save one operation (if that will have any effect).

Yes. You can also multiply the AO on Albedo inside Photoshop, then you will need to pull the shadows from from Albedo and amplify them a bit in order to multiply it by 0.5 for specular, it get's a little dirty but it works. I've explained here: http://polycount.com/discussion/comment/2524408/#Comment_2524408
But to answer your question more clearly, doing a multiply inside material editor doesn't hit your performance.

Ubuska

Thanks for your tips! Saved some tips for future use.

Wenceslaus

Thank you for the answer!
I now have a little issue with the LUT_2 file you have posted... LUT_1 works still realtively OK.


*edit: Silly me, I've just forgot to specify it is ColorLookupTable in the texture group in the texture details-

Maximum-Dev

Tip 07 - Sense of scale.

Hello good people of polycount.

I was working on a very small thing, mainly for learning purpose.
Usually when working on a landscape the one big issue is having no correct sense of scale. When you're doing level design it's sometimes very hard to know how everything feels from a player perspective, how big is this rock? how long is that path? how high is that hill? how large is that field? These are all sort of questions that I'm always dealing with.

When doing level design, what I've been always doing was to place the mannequin mesh here and there, look at it to get a sense of how big everything is. But that's actually not very helpful. The moment the mannequin isn't placed right next to what you're looking at, you lose the sense of scale. And on top of that, I got tired of placing mannequins here and there all the time.

For instance look at the scene below, the rocks look nice, but there's no way you'd know how big they are. And knowing the scales is actually more important than making it look good.



So what I came up with was to create a very small and simple grid function that tiles a grid on the landscape in world space, the easy way.

Here's the function:



And here's how it's setup in the landscape material. It get's all the inputs, with a BreakMaterialAttributes all outputs are broken and fed into the final input pins. Nothing complex.



A few parameters are exposed to material instance.

Opacity: Controls the grid opacity.
Specular: Preferably set to 0.
Roughness: Preferably set to 1.
Size: How much the grid is tiled.



I'm using a size of 1200 as you see. I know that makes the red squares as big to fit three sleeping dudes. (Outlined by blue).
And just knowing each red square can fit 3 sleeping dudes, I'm now instantly able to have a correct sense of scale everywhere without needing to place a mannequin or anything else, simply by changing the Grid - Opacity from 0 to 1.

Check out the squares I've outlined with green, now you know precisely how big the rocks are.



If you find this useful, you can download the function from here and put it in your content folder.

stilobique

Yeah, thanks to share your function ! You can add more information and description to add your function on your palette panel.

Ootrick

Gorgeous dude! love the scale idea... well played that would be super useful: Put it on the Unreal Marketplace! .I'd actually love to know what kind of lighting procedures you use, especially the desert scene and how you balance things like exposure and indirect light intensity, you seem to have a very keen eye for lighting too.  Subbed! 

Maximum-Dev

stilobique, Correct. Makes life easier.

Ootrick, Thanks. For lighting after 4.15 I'm using Movable directional and Skylight + Cubemap loaded in PPV. LPVs enabled too. I have the same setup here and there, only values and cubemaps differ from project to project. My other microphone was busted, got a new one today and planning to do lots of tutorials from now. =D

macoll

Thanks for sharing Max, always cool, gg

Xendance

I'd appreciate if you posted breakdowns of the trees themselves. How the leafs were made, how the branches are structured, how did you bake the billboard and so on.

r4ptur3

fantastic breakdowns!  thank you so much!

Martoon

Thanks for the helpful breakdowns and tips! Extremely helpful.

Maximum-Dev

Hi all,

Small article published here thought you might find it useful.
https://80.lv/articles/rendering-scanned-vegetation-in-real-time/
The big redwood forest breakdown is being worked on.

Good wishes, in particular.
~Ali

Maximum-Dev

Tip 08 - Macro color variation.

From large surfaces such as landscapes to smaller objects like rock formations. World space color variation is always the key to make things look more natural and interesting. This function gets your Albedo and outputs parameters to the material instance for you to introduce any sort of color variation to the surface at any scale, using a single RGB Texture Map.






You can download the function from here.

homart

what's the performance cost of this?! Thanks for sharing the love !

Maximum-Dev

homart said:

what's the performance cost of this?! Thanks for sharing the love !

Once used in a material it adds:

Base pass shader with only dynamic lighting: 27 instructions

Vertex shader: 1 instruction

Texture samplers: 1

So it's quite cheap.
Glad you find it useful

Maximum-Dev

Just came across the values to recreate UE4's old tonemapper curve using Filmic Tonemapper. This can be useful for those who want to properly lower the Filmic Tonemapper's effect and not completely disable it. You can roll the values back slightly towards these values of the old curve.

Old Tonemapper Curves:

Slope = 0.98;

Toe = 0.3;

Shoulder = 0.22;

BlackClip = 0;

WhiteClip = 0.025;

Source

Maximum-Dev

Tip 09 - Macro Normal variation.

Again this is about large surfaces such as landscape. Variation in color makes the surfaces look nice up to a certain distance. But looking at a large surface from far away, that color variation alone isn't enough and needs to be coupled with macro normal variation to break up the lighting on the surface. Now this isn't anything complex or fancy, just a very simple function that can be helpful at times when working with landscapes or other type of vast surfaces.






You can download the function from here.

StefanA

Thanks so much for sharing your assets, I'm loving each update. I'm having an issue importing your latest .uasset files however, they don't seem to appear within my project (even a new blank project). Previous u.assets have worked fine though... Does the GlobalNormalVariation.uasset require a specific version of UE4?

Maximum-Dev

StefanA said:

Thanks so much for sharing your assets, I'm loving each update. I'm having an issue importing your latest .uasset files however, they don't seem to appear within my project (even a new blank project). Previous u.assets have worked fine though... Does the GlobalNormalVariation.uasset require a specific version of UE4?

I'm on 4.16.2 at the moment. In case you're using an older version that might explain it. For some reason UE4 does not have backwards compatibility. And I'm glad you find these useful.

Maximum-Dev

Tip 10 - Mask Modifier.

It's been a while I've been building a whole library of modular functions that I can plug and play in every material. My initial goal was to save a bunch of time every time I move to work on a new project and I feel like I've achieved it. Once starting a new project, all I'd need to do is to copy my functions library over and start placing them in my materials where needed, cutting out the need to re-do the same setups over and over again in different projects/materials. I hope these will help you save some time too.



You can of course add any other type of control inside the function.
Download the function from here.

FishMan

Hey, thanks for the work you're doing and all the usefull stuff.
Also do you know that you can change the inputs sort priority and thus make their order more familiar, like: red, green, blue instead of green, blue, red?

PixelGoat

Great tips in here!  

Maximum-Dev

FishMan, I actually never paid attention to that. That's quite nice thing you pointed out there. Thanks!
PixelGoat, Thanks man, I'm glad to hear that from you.

Derjyn

Thanks for all the shares Maximum-Dev.

Another tip: use Saturate over Clamp nodes if you are after 0-1.  It's cheaper, if not practically free (and the node is smaller, if you are OCD on organization).

radiancef0rge

its not like this was built for performance, the alu cost of clamp over saturate is minor.

Derjyn

True- but it can add up.  I like having my "finger on the pulse" so to say, and if I can shave off 0.5 milliseconds (project-wide, not saying that's the difference between clamp and saturate) as well as save some graph space as a side-effect, it's not a bad habit to have

Maximum-Dev

Tip 11 - DFAO Specular Occlusion.

Hi everyone!

Some might not be aware, for enabling specular occlusion from Skylight you have to put a zero in front of "r.AOSpecularOcclusionMode" cvar.

I have a extreme case showing that. Below is the comparison slide.

https://imgsli.com/MTY0NQ

Left is "r.AOSpecularOcclusionMode 1" (Specular Occlusion off).
Right is r.AOSpecularOcclusionMode 0" (Specular Occlusion on).