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Background color with skydome

Message 1 of 11
7292 Views, 10 Replies

Background color with skydome

Hi there;

I have a skydome light lighting the scene and made it invisible by putting black into the camera slot color, great.

But now I want to control that black color, so I change the color in the camera´s background color..., nothing happens.

So, as far as I know, the black color in the camera visibility slot of the skydome camera is JUST for hiding the light to camera rays, not suppose to change the background color.

So..., if I hide the light to camera rays..., then what is the black color the background shows now?, the camera´s own background?, Or is it something else?.

Thanks in advance.

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Message 2 of 11
in reply to: joie

If set the Visibility > Camera to 0, then you're not going to see whatever you connect to the Color.

There's no background, that's why see black (rgb 0 0 0)

The camera ray doesn't hit anything in the scene, there's no background shader or visible skydome, so Arnold terminates the ray after a certain point and all you get is 0 0 0

// Stephen Blair
// Arnold Renderer Support
Message 3 of 11
in reply to: joie

As Stephen says if you tweak the camera visibility in the skydome and put it to zero .. than you ain't getting anything from there. If you instead wanna tweak the skydome camera color differently than the rest you may for example use a rayswitcher and tweak colors there.



Message 4 of 11
in reply to: joie

@Max Tarpini
Try to unplung all the connections from aiRaySwitch and leave only The Shadow
hit render
unplug the shadow, and plug all the rest and hit render
you get a nice bug render!

Message 5 of 11
in reply to: Anonymous

oh you don't even need to plug/unplug .. just keep tweaking rayswitch sliders and scene update is gone at some point. ctrl+u is your friend 🙂

Message 6 of 11
in reply to: joie

You did not understand me, what I wanted to tell you is that there is a bug in aiRaySwitch
in fact aiRaySwitch does not take into account other parameters when Shadow are not mapped.
What if I want to leave the aiRaySwitch.Shadow empty and map all other parameters, no things happen in this case,(render black)
The camera parameter in aiRaySwitch work only when Shadow are mapped
the other parameters Diffuse Reflection, Specular Reflection, Diffuse Transmission, Specular Transmission have no effect even when Shadow are mapped.
I was expecting that I can have 8 bit file plugged to Camera to show in the background, a blured image for Diffuse Reflection,something like 8k HDRi for the Specular Reflection etc.. (like the dead mentalray rayswitch)
but there is a bug

Message 7 of 11
in reply to: Anonymous

I'm waiting for a workaround for that too

Message 8 of 11
in reply to: joie

take care that here (when connected to a light ..) with 'shadows' we really mean 'light' .. so if you have a black color there .. you ain't gonna have any light .. in fact looks like Arnold builds its importance sampling map on that. from there let's say that important parts of the map are going to be direct light and the other indirect (ie reflections) .. so I wouldn't mess up too much on that anyway with a rayswitch .. there's no reason if you are doing it for performances .. it takes care already Arnold core 🙂


Message 9 of 11
in reply to: joie

Let's say I have three different textures to map , one for the background (Camera) another for the reflection and a third for the specular
The logic behind the node rayswitch is very simple:(switching between 2 or more things, witch is not!)
what I noticied is this:
The camera in aiRaySwitch does not work if the aiRaySwitch.shadow are not mapped(texture or color)
So I can plug the same texture to camera and shadow but I WANT TO SEE Diffuse Reflection, Specular Reflection etc.. from other textures, witch is not in this case.
for me it's a bug the Team should correct it

Message 10 of 11
in reply to: joie

I told you above why this is happening. Arnold builds an importance map from your IBL and hardcores that into the scene for best performances. Rayswitcher as you want to use it is an hack and not the intended way to use it. It's a limitation (for a physically based renderer) not a bug.

If you really wanna have different plugs for diffuse/specs etc. you have simply to bypass the importance sampling map step .. and for that you don't use a standard-skydome but a simple dome sphere(with inverted normals) around your scene with attached a rayswitcher where you plug your different texture.

In other words you wanna be physically correct ? Let Arnold do his stuff. You wanna hack around ? Don't ask Arnold to do it for you. It's up to you knowing how to do it. Simple as that 🙂


Message 11 of 11
in reply to: joie

I was eager to understand the why of the how, and voilà it became very clear
Thank you for your effort Max Tarpini

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