Dark Artifacts in sky dome and emission aov when compositing in Adobe After Effects and Blackmagic Davinci Resolve and Fusion

[thejedi]

Hi everyone

I am battling to remove a strange artifact showing of a dark dot and sometimes a dark line when compositing the emission layer in Adobe after effects and Davinci Resolve

I have attached the simplified houdini file with the sky texture and its ready to render to see where the problem is

So, I render the following AOVs from Houdini 18.0.532 using the latest redshift 3.0.27

I render the following aovs as exr:
beauty_aux.exr
diffuse.exr
emission.exr
gi.exr
reflection.exr
refraction.exr
specular.exr
z.exr

The sky image is an exr which I applied on a redshift dome light inside houdini

I follow the guideline on how to composite all these aovs into a final image in Adobe After Effects and Davinci Resolve and i place the layers in the following order: diffuse, + gi + specular + reflection + refraction + emission

The emission aov ends up showing a dark spot especially arounnd the area where the sub is at its brightest
sometimes it even shows an entire dark line again around the area in the image where the sun is supposed to be at its brightest

this artifact only appears when I switch my project setting to run on 32bit per channel

and even when i try to load the beauty aov exr, i get the same dark spot so this issue is not just limited to the emission aov

Then moment i switch the project to run on 8bit per channel, the dark dot and dark line artifacts dissapear
but then in Adobe after effects, i end up losing the ability to bring back the sky colour and details, the image ends up looking flat and even when i adjust the curves on the colours, the image remains flat looking

Thank you

__Sky_Artifact.rar

render.zip

Edited September 7, 2020 by thejedi

[UserNoah]

A kinda old topic so you probably figured that out already but in case you didn't:

 I just looked at your render in Fusion. If something like that is happening then there are only a limited number of things that could have happened. In your case, it's very simple. Your diffuse is empty as you have used a dome light, you don't need that. Looking further, the Emission channel doesn't have a solid alpha exactly where that dark spot is in your image. Now the diffuse channel is visible through it. But there is also a second issue and that is why the Alpha isn't solid and why all Applications seem to strike. Your colors are INSANELY high. So high that Fusion (and other Software) can't handle it.

These are the color values directly next to that spot:

And these are the color values on that spot:

The reason you might not see it in 8bit is that AE might clip it and just show white. 

I have ditched AE for comp work so I can't tell you how to fix it in AE but I can tell you how to fix it in Fusion. A normal BrightnessContrast tool won't help as this can't handle these values either, but you can clip them using a CustomTool. Copy and paste the following code into Fusion and wire your emission channel into that CustomTool.

{
	Tools = ordered() {
		CustomTool1 = Custom {
			CtrlWZoom = false,
			Inputs = {
				LUTIn1 = Input {
					SourceOp = "CustomTool1LUTIn1",
					Source = "Value",
				},
				LUTIn2 = Input {
					SourceOp = "CustomTool1LUTIn2",
					Source = "Value",
				},
				LUTIn3 = Input {
					SourceOp = "CustomTool1LUTIn3",
					Source = "Value",
				},
				LUTIn4 = Input {
					SourceOp = "CustomTool1LUTIn4",
					Source = "Value",
				},
				RedExpression = Input { Value = "if(r1 > 1000, 100, r1)", },
				GreenExpression = Input { Value = "if(g1 > 1000, 100, g1)", },
				BlueExpression = Input { Value = "if(b1 > 1000, 100, b1)", },
			},
			ViewInfo = OperatorInfo { Pos = { 1320, 412.5 } },
		},
		CustomTool1LUTIn1 = LUTBezier {
			KeyColorSplines = {
				[0] = {
					[0] = { 0, RH = { 0.333333333333333, 0.333333333333333 }, Flags = { Linear = true } },
					[1] = { 1, LH = { 0.666666666666667, 0.666666666666667 }, Flags = { Linear = true } }
				}
			},
			SplineColor = { Red = 204, Green = 0, Blue = 0 },
			NameSet = true,
		},
		CustomTool1LUTIn2 = LUTBezier {
			KeyColorSplines = {
				[0] = {
					[0] = { 0, RH = { 0.333333333333333, 0.333333333333333 }, Flags = { Linear = true } },
					[1] = { 1, LH = { 0.666666666666667, 0.666666666666667 }, Flags = { Linear = true } }
				}
			},
			SplineColor = { Red = 0, Green = 204, Blue = 0 },
			NameSet = true,
		},
		CustomTool1LUTIn3 = LUTBezier {
			KeyColorSplines = {
				[0] = {
					[0] = { 0, RH = { 0.333333333333333, 0.333333333333333 }, Flags = { Linear = true } },
					[1] = { 1, LH = { 0.666666666666667, 0.666666666666667 }, Flags = { Linear = true } }
				}
			},
			SplineColor = { Red = 0, Green = 0, Blue = 204 },
			NameSet = true,
		},
		CustomTool1LUTIn4 = LUTBezier {
			KeyColorSplines = {
				[0] = {
					[0] = { 0, RH = { 0.333333333333333, 0.333333333333333 }, Flags = { Linear = true } },
					[1] = { 1, LH = { 0.666666666666667, 0.666666666666667 }, Flags = { Linear = true } }
				}
			},
			SplineColor = { Red = 204, Green = 204, Blue = 204 },
			NameSet = true,
		}
	},
	ActiveTool = "CustomTool1"
}

This will clamp the values above 1000. You can go lower you can go higher, but the difference between that insanely high spot and your normal colors is so huge that you will always have a bright white spot there. I was able to recover most though by using a ColorCorrector after the Custom tool.

Nevertheless, think of ditching that and simply use the HDRI inside of AE or Fusion. It's so easy to import the camera into Fusion and you don't have to deal with these crazy numbers.