VrayAmbientLight

[Da_elf]

isnt real ambient occlusion the calculation to find out whether or not ambient light is reaching a surface? ie: the same stuff as calculating an overcast day? and wouldnt the dirtmap thing be just a fake for ambient occlusion.

[mmikee]

isnt real ambient occlusion the calculation to find out whether or not ambient light is reaching a surface? ie: the same stuff as calculating an overcast day? and wouldnt the dirtmap thing be just a fake for ambient occlusion.

Pretty much. But AO indirect lighting is so fast to render . And when you can sample the environment for color, it can look real nice as well. IMHO not as good as GI, but alot of times good enough, especially with moving objects. I would love to see the Vray dirt be able to sample the environment. This is one of the reasons we use MR so much for animation.

It would also be nice to be able to use Vray dirt as a light shader.

Regards,
Mike

[murko-sk]

I would love to see the Vray dirt be able to sample the environment. This is one of the reasons we use MR so much for animation.

Sorry for hijack, but could you pls tell how in short to setup that in MR ?

[mmikee]

There are a few ways to do this. The easiest way is to add an ao map to the projection slot of a standard omni light. Make sure that your omni is located at 0 0 0 coordinates. Then drag the ao map to an empty material slot in the mat editor. Change the distance to anthing you want. To sample the environment change the "mode" to 1. It is at 0 by default. Load whatever map you want for the environment. You can also use the background switcher to use a different map for the actual background.
The workflow for Maya is almost the same. If you have any questions about the other ways of doing this, just ask.
BTW, there is a simple tutorial for using the ao map as a light shader on my blog.

http://mikebracken.cgsociety.org/blog/

Regards,
Mike

[vlado]

I would love to see the Vray dirt be able to sample the environment.

This was planned, unfortunately it didn't make it into SP4, but will be added for the next update.

Best regards,
Vlado

[mmikee]

This was planned, unfortunately it didn't make it into SP4, but will be added for the next update.

This is great news !


Regards,
Mike

[flipside]

VRayAmbientLight adds the ability to create an ambient light in VRay, similar to Mental Ray or scanline ambient. Additionally, you can add AO in the form the VRayDirtMap. This is presumably no faster (or slower) than manually adding AO to all your materials, but provides the obvious benefit of a global control.

What seperates it from the VRay Dome Light is that it can use AO, rather than brute-force GI which doesn't provide the usual benefits of AO (ray distance, etc.)

Is the correct way to use this to simply add the light, and then drag a vraydirt map to the texture slot of the light? I don't get any good results, not looking anywhere near what I would expect AO to look like.

thanks

[duke2]

Is the correct way to use this to simply add the light, and then drag a vraydirt map to the texture slot of the light? I don't get any good results, not looking anywhere near what I would expect AO to look like.

thanks

Yeah that's what I did. Oh and tick the adjust to exposure checkbox.

[Jiri.Matys]

I dont get it. When I do what You said, there is AO, but when I change intensity or color of VRay Ambient Light, no change happens. Render is still the same.

So what is it for ? AO can be done through GI, so dont know why use Ambient Light.

[mmikee]

So that you do not have to use GI.


Regards,
Mike

[dlparisi]

Marc, are you planning on updating your AO script to include the new ambient light?

With apologies to Marc, I've been updating his AO script for a while now for in-house use...



I still have a little bit of testing to do on some of it so I'll post it when I'm more confident there's no bugs in it. Most of it's pretty self explanatory and the available options update depending on the method and options chosen. I've got it set up now so you can either override the materials with white or use the existing materials for both the "skylight" and the "ambient Light". Using the vraydirt method only allows for the default white since there's no other lights and it's using a vraylightmtl.

By default it switches vray camera exposure off and turns off displacement which were always PITA things I forgot to do when rendering an AO pass (there's checkboxes for them if you need it).

Suggestions welcome...

[duke2]

Hopefully this explains it a bit more.

[Jiri.Matys]

Ok, thanks a lot.

Maybe some update of vray help will be great.

[stevesideas]

So, the ambient light can be used in conjunction with a dome light ? So if im understanding this correctly, for a faster way to calc AO and burn into a scene, use this method instead of the GI AO method ?!

[duke2]

So, the ambient light can be used in conjunction with a dome light ? So if im understanding this correctly, for a faster way to calc AO and burn into a scene, use this method instead of the GI AO method ?!

I guess you could use it with a domelight..... but I don't know why you would.