Need help. Diffuse background for interior scene

[erich_lampart1]

I would like to know, how I can achive such a diffuse, blury background picture with Vray5 and 3DSmax 22 As you can see on the picture attached. The back ground is kind of diffuse and overexposed.

I have alredy tried many ways, but I'm still not happy with the result.

Should I use a plane background with an Vray Mtl and plug the bitmat to the self-illumintaion slot?
Together with an vray sun for the shadows and a dome light?

I would like to find a solution without HDRI, because I want to use many different backgrounds for my interior renders. With HDRI the selection of pictures is limited.

Thanks for your help guys!

[fixeighted]

Light the scene as you would normally and render the image with an alpha for the windows.
Make sure the dome/hdr/sky is set to invisible and that the background is black.
You can then use whatever background you wish, blurring and cc'ing it to your liking

[erich_lampart1]

Thank you Fixeighted.
So I guess you mean I have to use the Vrayalpha renderelement, right?
https://docs.chaos.com/display/VMAX/VRayAlpha

And later place the background picture behind in Photoshop?

Other way arround:
If I have a curved plane with an texture mapping in my 3DS secen, I could use the vraybackground render element
https://docs.chaos.com/display/VMAX/VRayBackground
and andjust the brightness, blury and so on PS?

Same effect different approache??

Am I on the right track or completely wrong?

Thank you for your patience!

[^Lele^]

"The Background Render Element includes just the background as set in the scene"

Your textured plane won't come through that way, as the image you're mapping is not set to use the environment background slot.
You can instead use a vrayMtlSelect render element, pointing it to the material you used on the plane.
To ensure that's visible behind glass, you'll need to set your glass shader to "affect all channels".
See the attached scene (replace the referenced HDR with something you have.)

EDIT: replacing background after the fact is going to be tricky, as that may be seen in reflections and refractions.
Not a simple thing to achieve, in general.

[erich_lampart1]

Grazie Lele,

thank you for this tip.
It works fine with CPU but not with GPU rednering.... is this correct?

Cheers

[^Lele^]

Correct, the vrayMtlSelect RE isn't supported.
You can always refer to the linked docs page to figure out if the GPU engine is going to suit your needs, as that's periodically updated.

[erich_lampart1]

OK, thank you Lele for the link, very helpful!

So you also think that I need to tweak arround in PS to achive the same background as on my first picture attached?

Thanks mate!