My SSAO Implementation

[LordHippo]

Hi all,

 

Here is my SSAO implementation.

 

I've got some inspirations from HBAO, but it is a completely different method and is MUCH more optimized.

I've also implemented Crysis 1 SSAO to be able to compare.

 

The time values you see on the image is only SSAO render time. Screen resolution is 1280*720, and the SSAO is rendered in full resolution on a GeForce GTS450 card. ( FPS = 1000 / time )

 

Model from Ywa by Harry ( http://harrysite.net/work/index.php?x=browse )

 

I've also implemented a method for false occlusion removal:

 

It's a combination of a method implemented by Crytek in Crysis1, and my own method. It still needs more optimizations.

 

Another improvement I've made is using a half resolution depth buffer for the SSAO rendering. The method is used in Uncharted2.

As you can see on the picture, this method almost doubles the speed of SSAO, with almost no visual artifacts.

 

From a technical point of view, the main bottleneck of the SSAO algorithms is their texture fetches. More specifically, they heavily do GPU cache trashing, because of their random sampling basis. Also cache trashing decreases shader performance dramatically.

So any method that reduces cache trashing would boost up the SSAO.

By using a half resolution depth buffer, one of the main benefits is that texture sampling points get closer, so the amount of cache trashing is reduced.

Also as seen in the results, there is no noticeable difference or artifacts.

 

So with this technique, you gain much more performance, with no visual cost! That's the magic of OPTIMIZATION

 

I will share it to the community when I'm done with false occlusion removal optimizations.

 

Also check the album page for more shots.

 

BTW, I'll be happy if anyone have any visual or technical suggestions, cause I want to "get rid of it, once and for all"

[Scott Richmond]

Fantastic work mate! Really cool stuff. I can't wait to get my own hands on this. You really should consider also packaging it up as an injector so people can use it on other games - Its a surprisingly popular mod type among Fallout, Skyrim, GTA, etc.

 

I would be interested to see what would happen if you halved again the resolution depth buffer so its 1 quarter of its original size. See if you can find that point where the speed returns versus the image quality meet that sweet spot.

 

Once you're done with SSAO you might want to take a look at this brand new AA method I read about last night, Its making a real big splash in the graphics community because its extremely fast and does almost as well as really high end AA settings: http://www.iryoku.com/smaa

Open source, so you can go at it.

[LordHippo]

Fantastic work mate! Really cool stuff. I can't wait to get my own hands on this. You really should consider also packaging it up as an injector so people can use it on other games - Its a surprisingly popular mod type among Fallout, Skyrim, GTA, etc.

 

I would be interested to see what would happen if you halved again the resolution depth buffer so its 1 quarter of its original size. See if you can find that point where the speed returns versus the image quality meet that sweet spot.

 

Once you're done with SSAO you might want to take a look at this brand new AA method I read about last night, Its making a real big splash in the graphics community because its extremely fast and does almost as well as really high end AA settings: http://www.iryoku.com/smaa

Open source, so you can go at it.

 

Thanks Scott.

I've never heard of "injectors" before, and have no idea how to make them. But it would be interesting to make them, and test my shaders in AAA games!

I will test the quarter res depth buffer, but I think there will be some halos around the objects. Currently running SSAO with half-res depth and in %75 resolution takes about 1.5ms in 720p on geforce GTS450 which is really good.

 

About the AA method (SMAA), I think the performance is not good. It runs on GTX295 (which is really powerful) in 1.8ms with 4x memory footprint.

So in my opinion, MLAA is the best post AA technique for the current generation of hardwares. I'll try to implement all the AA methods such as MLAA and SMAA and compare them in terms of quality, performance and memory footprint.

[Josh]

How are you measuring time? A GPU performance query, I hope.

 

Very nice stuff.

[LordHippo]

How are you measuring time? A GPU performance query, I hope.

 

Very nice stuff.

 

Thanks Josh.

 

No, I'm just measuring the frame time with and without the whole SSAO rendering (copying buffers, rendering SSAO, blurring it) and subtract them.

Can you tell me more about "GPU performance query"? I've googled it and found no results for OpenGL.

But this time was the same in any scene I've tested, so I think it's accurate enough.

Correct me if I'm wrong

[Scott Richmond]

In regards to injectors, you should take a look at the work of ENB. He is one of the most popular shader modders, with shaders for almost all games. His website is here: http://enbdev.com/index_en.html

The way injectors work is that you take a slightly modified d3d9.dll and drop it into the game directory. It redirects the initial call for the games shader file to your own one. From there you can inject your own shader and then pass back to the games one, or discard it entirely.

[Josh]

Thanks Josh.

 

No, I'm just measuring the frame time with and without the whole SSAO rendering (copying buffers, rendering SSAO, blurring it) and subtract them.

Can you tell me more about "GPU performance query"? I've googled it and found no results for OpenGL.

But this time was the same in any scene I've tested, so I think it's accurate enough.

Correct me if I'm wrong

NVidia cards have a high-precision GPU performance query, I've used it, but can't remember the commands off the top of my head. I think it's an OpenGL extension. It will tell you exactly how long an operation takes.

[Ywa]

Great to see someone is using the model properly. While I don't understand anything of the technical stuff, it does look quite good.

[LordHippo]

Great to see someone is using the model properly. While I don't understand anything of the technical stuff, it does look quite good.

 

Thank you so much for the model. It really helped me a lot in development

[L B]

Can you do a comparison shot of that model with LE2's default SSDO vs. your SSAO?

Looks great, by the way.

[Josh]

I would like to see a comparison of his SSAO with diffuse textures turned on and off.

[LordHippo]

Can you do a comparison shot of that model with LE2's default SSDO vs. your SSAO?

Looks great, by the way.

 

Which model do you mean?

I've already posted that comparison on the cave model.

[Canardia]

I am Ron Paul, and I approve this shader.

[L B]

I would like to see a comparison of his SSAO with diffuse textures turned on and off.

He already gave one with diffuse off, I wanna see it on.

[Josh]

I mean a comparison of SSAO on and off, with diffuse and everything else enabled.

[LordHippo]

I mean a comparison of SSAO on and off, with diffuse and everything else enabled.

 

So I've tried my best to turn everything enabled.

 

Notice that the effect is not noticeable side by side. The best way is to have a Photoshop layered image and switch them on and off.

Also the effect of SSAO is not noticeable, because the diffuse texture of the models have baked AO.

[franck22000]

Let me contribute to this here is a comparison with and without lordhippo SSAO:

 

 

 

and on this shot you can see the power of this shader (i have tweaked the shader to make the ssao appear more in dark areas and less in lighted areas.

 

[Josh]

Wow, that last shot is amazing. This is by far the best SSAO I've ever seen. Better than mine, and much better than Crysis.

 

One thing you should test before you call it finished is how well it handles distant objects. I had problems with artifacts on distant terrain when I was implementing mine.

 

I'm also interested to see how it reacts when you have contours on terrain in the distance. Will it capture that detail like in this shot?:

[Clackdor]

Will somebody explain to a graphics noob what I'm looking at here? I'm having a hard time seeing the differences on the cave screenshot comparison.

[LordHippo]

Will somebody explain to a graphics noob what I'm looking at here? I'm having a hard time seeing the differences on the cave screenshot comparison.

 

As i said, the difference in the cave shot is hard to notice. Cause the model has AO baked in its textures.

[Rick]

Is there a scene or situation where it's easier to see the benefits of this?

[Pixel Perfect]

Surely we have all noticed the differences in our editors/games with SSDO turned on and off; even if its hard to tell the difference between the various illustrations presented. The fact that LordHippo's is almost twice as fast as our current one is in itself of huge benefit is it not!

[LordHippo]

The main problem is that I'm not an artist, and can't make a good use of the shader.

Also I'm not allowed to publish any shots from the game we're working on.

[Rick]

Are you going to provide this for the LE community in some fashion? Paid or not? Maybe an artist on here would be willing to make some scenes that really show this off. I'm just curious as to the different look it provides. From the black/white picks it's clear to see the difference, but would just be nice to see it in a somewhat finished scene with all the colors where it makes a big difference. I'm sure it excels in certain situations and from Josh's reaction I'm sure it's a really cool feat, but I feel awkward and not sure how to react because I literally can't see any difference in the finished scenes presented :/

[Michael Betke]

Where can I download this nice addition? How does it behave on bright surfaces? I think this is often a difficult scenary because it makes edges look a bit blurry.