SSAA + GammaCorrection - dark colors issue

Fluqz · May 18, 2020, 3:32pm

Hey, im using post processing to improve realism in my scene. This works more or less. The main problem is that dark colors have a weird behavior when SSAA is enabled. Here a before/after demo. Left is with renderPass, GammaCorrection & FXAA, right is with SSAA, GammaCorrection & SAO. See the black suit or the brown pants in the bottom right corner. Or this jsFiddle

This is my code

My renderer:

        this._renderer = new THREE.WebGL    Renderer( { antialias: true, alpha: true } )
        this._renderer.setPixelRatio(this.ratio)
        this._renderer.setSize( this.w, this.h )
        this._renderer.setClearColor(0xffffff)
        this._renderer.outputEncoding = THREE.sRGBEncoding
        this._renderer.shadowMap.enabled = true
        this._renderer.shadowMap.type = THREE.PCFSoftShadowMap
        this._renderer.toneMapping = THREE.Uncharted2ToneMapping

Postprocessing:

        this.composer = new EffectComposer(this._renderer)
        this.composer.setSize(this.w, this.h)

        this.ssaaRenderPass = new SSAARenderPass(this._scene, this.camera, 0x000000, 0)
        this.ssaaRenderPass.setSize(this.w, this.h)
        this.ssaaRenderPass.unbiased = true
        this.ssaaRenderPass.sampleLevel = 4

        this.renderPass = new RenderPass(this.scene, this.camera)
        this.renderPass.setSize(this.w, this.h)

        this.SAO = new SAOPass(this._scene, this.camera, true, true)
        this.SAO.resolution.set(2048, 2048)
        this.SAO.params.saoBias = .01
        this.SAO.params.saoIntensity = .0014
        this.SAO.params.saoScale = .3
        this.SAO.params.saoKernelRadius = 43
        this.SAO.params.saoBlurRadius = 4
        this.SAO.params.saoMinResolution = 0

        this.gammaCorrection = new ShaderPass(GammaCorrectionShader)

        this.FXAA = new ShaderPass(FXAAShader)
        this.FXAA.material['uniforms']['resolution'].value.x = 1 / (this.w)
        this.FXAA.material['uniforms']['resolution'].value.y = 1 / (this.h)

        this.composer.addPass(this.renderPass)
        this.composer.addPass(this.ssaaRenderPass)
        this.composer.addPass(this.SAO)
        this.composer.addPass(this.gammaCorrection)
        this.composer.addPass(this.FXAA)

mjurczyk · May 18, 2020, 4:57pm

Postprocessing seem to overall alter the colors and contrast. Maybe try adjusting gammaFactor in the original renderer, lower it a bit?

https://threejs.org/docs/#api/en/renderers/WebGLRenderer.gammaFactor

(May be related: https://github.com/mrdoob/three.js/issues/18451)

Edit: I may be wrong on this one, but GammaCorrection pass should always be at the end of the postprocessing pipeline - moving it may also help?

Mugen87 · May 18, 2020, 5:08pm

Nope, FXAA should always be done in the final color space. So it usually comes at the very end of the pass chain.

@Fluqz Do you really need SSAA and FXAA? Isn’t it sufficient to just use FXAA?

drcmda · May 18, 2020, 6:28pm

i am terribly sorry to hijack this topic with a small question, but this looks stunning for something that’s presented on the web. could you recommend any resources that go into baking? the ones that i have seen don’t seem to yield results like that, not even close. yours looks actually real.

gkjohnson · May 18, 2020, 6:58pm

I’m not sure why adding or removing SSAA would cause any color issues like you’re showing but I notice that you’re setting the renderer outputEncoding to sRGBEncoding and also adding a gamma correction pass. You should just be doing one or the other:

this._renderer.outputEncoding = THREE.sRGBEncoding

// ...

this.gammaCorrection = new ShaderPass(GammaCorrectionShader)

Fluqz · May 19, 2020, 8:40am

I do not use baking at all, because every part of the scene is dynamically positioned. I have multiple lights that I tried to configure to have a very soft shadow. Also using the SAO to generate a Ambient Occlusion effect works quite well, but it costs a lot of performance. For that reason I have two render states: While moving Im rendering without SAO and on mouse up I render with SAO, so the user has no lag when orbiting. Its not the most elegant way, but the only one I see right now.

Fluqz · May 19, 2020, 11:14am

I forgot to mention that I only use one at a time. In code the passes were disabled, but that wasnt clear enough sry. I changed the description.
Left picture is with renderPass, gammaCorrection & FXAA, the right picture is with SSAA, SAO & GammaCorrection, in that order. I change betweent the two onMouseMove/onMouseUp.

I tested it and didnt see any effect

Deleting the this._renderer.outputEncoding = THREE.sRGBEncoding did not work as well. I also removed it from the textures. texture['encoding'] = THREE.sRGBEncoding makes no difference.

I also removed the unrelated passes from the chain.

this.composer.addPass(this.ssaaRenderPass)
this.composer.addPass(this.gammaCorrection)

SSAA and GammaCorrection together seems to be the problem.

I will try to make a jsFiddle as soon as possible.

looeee · May 19, 2020, 11:28am

Could you use SSAO instead?
Also, you can try SMAA instead of FXAA.

Fluqz · May 19, 2020, 12:38pm

Here is a jsFiddle which shows the problem. OnMouseUp the Shark gets way darker and has less gradient. Also see the cube reflection from the spotlight. The gradient is also getting smaller

@looeee I tried the SSAO before but it didnt look good at all. I will look into the SMAA, thanks

Fluqz · May 27, 2020, 12:04pm

Does anyone have an idea where this comes from? https://jsfiddle.net/f3qksgnj/

JonRiv · June 3, 2020, 4:13pm

Lowering SSAA.sampleLevel to 1 enhanced greatly the color problem, while keeping AA. Adding a background color to the scene stopped the background color changing problem. See here : https://jsfiddle.net/oj8914ph/

Jun-03-2020 09-07-23

Fluqz · June 4, 2020, 2:01pm

Thanks, setting the sampleLevel to 1 fixes the colors, but decreases antialiasing as well.
So this is not really a solution for me.

Tried SMAAPass, but is also kinda stairy

Fluqz · September 3, 2020, 2:16pm

So when increasing the sampleLevel of SSAA, it seems like its loosing contrast.
Is this even a desired behavior of SSAA? Why would it change colors? Isnt it for antialiasing only?

Fluqz · November 24, 2020, 5:39pm

new · August 17, 2023, 2:52am

I am facing the same issue, however, in my case passing {type: FloatType} doesn’t have any effects. Are there any updates regarding this issue?

Here on the picture below left is RenderPass + SSAA + Gamma, right is RenderPass + Gamma.

Mugen87 · August 17, 2023, 7:54am

@drcmda The question of @new is not about SSAO. So need to plug projects here.

Any chances to provide a live example that shows what you are doing? Color related issue with SSAA have been fixed in recent versions of three.js. You should also not use GammaCorrectionShader anymore but OutputPass which does tone mapping and color space conversion in one go.

Mugen87 · August 17, 2023, 8:02am

My problem is that you use literally any opportunity in this forum to plug projects instead of answering the questions of users. This is considered as off-topic for sure…

drcmda · August 17, 2023, 8:07am

just realise this now, i misread aa as ao. i just tried to help, i had no intention to “plug”.

@N8Three, you were made mod in threejs-discord, could be be mod in here, too?

Mugen87 · August 17, 2023, 8:09am

Sorry, but @new asked about SSAA (not SSAO). That’s my point.

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SSAA + GammaCorrection - dark colors issue

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