question

Jose Miguel avatar image
Jose Miguel asked ·

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.

colorskydome
10 |600 characters needed characters left characters exceeded

Up to 5 attachments (including images) can be used with a maximum of 2.0 MiB each and 9.8 MiB total.

rachid Hadj Abderrahmane avatar image
rachid Hadj Abderrahmane answered ·

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

10 |600 characters needed characters left characters exceeded

Up to 5 attachments (including images) can be used with a maximum of 2.0 MiB each and 9.8 MiB total.

Max Tarpini avatar image
Max Tarpini answered ·

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 :)


10 |600 characters needed characters left characters exceeded

Up to 5 attachments (including images) can be used with a maximum of 2.0 MiB each and 9.8 MiB total.

rachid Hadj Abderrahmane avatar image
rachid Hadj Abderrahmane answered ·

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

10 |600 characters needed characters left characters exceeded

Up to 5 attachments (including images) can be used with a maximum of 2.0 MiB each and 9.8 MiB total.

Max Tarpini avatar image
Max Tarpini answered ·

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 :)


10 |600 characters needed characters left characters exceeded

Up to 5 attachments (including images) can be used with a maximum of 2.0 MiB each and 9.8 MiB total.

rachid Hadj Abderrahmane avatar image
rachid Hadj Abderrahmane answered ·

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

1 comment
10 |600 characters needed characters left characters exceeded

Up to 5 attachments (including images) can be used with a maximum of 2.0 MiB each and 9.8 MiB total.

I'm waiting for a workaround for that too

0 Likes 0 ·
rachid Hadj Abderrahmane avatar image
rachid Hadj Abderrahmane answered ·

@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!

1 comment
10 |600 characters needed characters left characters exceeded

Up to 5 attachments (including images) can be used with a maximum of 2.0 MiB each and 9.8 MiB total.

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 :)

0 Likes 0 ·
Max Tarpini avatar image
Max Tarpini answered ·

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.


10 |600 characters needed characters left characters exceeded

Up to 5 attachments (including images) can be used with a maximum of 2.0 MiB each and 9.8 MiB total.

Stephen Blair avatar image
Stephen Blair answered ·

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

10 |600 characters needed characters left characters exceeded

Up to 5 attachments (including images) can be used with a maximum of 2.0 MiB each and 9.8 MiB total.

Write an Answer

Hint: Notify or tag a user in this post by typing @username.

Up to 5 attachments (including images) can be used with a maximum of 2.0 MiB each and 9.8 MiB total.

Welcome to the Arnold Answers community.

This is the place for Arnold renderer users everywhere to ask and answer rendering questions, and share knowledge about using Arnold, Arnold plugins, workflows and developing tools with Arnold.

If you are a new user to Arnold Answers, please first check out our FAQ and User Guide for more information.

When posting questions, please be sure to select the appropriate Space for your Arnold plugin and include the plugin version you are using.

Please include images, scene and log files whenever possible as this helps the community answer your questions.

Instructions for generating full verbosity log files are available for MtoA, MaxtoA, C4DtoA, HtoA, KtoA, and Kick.

If you are looking for Arnold Documentation and Support please visit the Arnold Support site.

To try Arnold please visit the Arnold Trial page.

Bottom No panel present for this section.