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VRay background texture multiplier settings


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I'm not sure whether this is a bug or I'm just not setting the adjustments correctly. I seem to have a light leak into transparent materials from a texture background.

Has anyone else encountered this?

In this image there are semi transparent panels that should just mostly capture the shadows and some small amount of transferred imagery from the background.

However as you can see the actual background seems to be making it's way quite strongly into the transparent panels.

The light is a VRAy sun set to about .5 and the background multiplier is set to 10. I'm guessing this may be too high but unsure why it would be generating right across the panels and not being at least partially blocked by obstacles in between the sun and the panels. Possibly I need to place more objects to block it or turn down the multiplier - however I'm setting it high to increase it's affect on the other surrounding textures and surfaces.

This is with FormZ 9.2beta with VRay 5 build 1615 - and imaging pass 1.



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What is the end result you are looking for?

What is the current background texture image?  Clouds on a blue sky? Or the forest scene? Or?

Is it a flat image or a spherical hdri or exr image?

In the past, I also had difficulty setting up an accurate background image so I simply made a large plane that I mapped the image onto.  Then you can easily place it just where you want it.  You can also  use a low powered emitter material here and it will act as an IBL for the scene if you desire.

Other thoughts would be the semi transparent glass material may be able to be adjusted so that it doesn't receive as much of the background image.  Using a double pane setup can help with this too.

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I believe what is happening is that you have not selected "sky" or other image map for your reflection and or refraction on your vray environment settings. This causes any reflective material to reflect your background. I think it's actually the refraction what affects glass materials to reflect the image. So try this selecting sky or other image under your refraction options and make sure you set the number to about 60+ so you can see the result.

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Yeah thanks I'll explore more of the options in the environment refractions and reflections settings.

Usually with VRay on other platforms the sunlight needs a generated sky tied to it to get the full effect happening and to 'bend light around corners' so to speak but it's often set up automatically.

But as I said - this is a flat environment background image texture so I expected it to only appear as refection or reflection where there are gaps in the visual line of sight to the background and that those would then be reflected or refracted onto other objects.  It should be operating as the equivalent of a 2D texture mapped background panel.

All of the objects are 3D objects - plants etc and there is lens depth focus blurring background objects... and there's alot more atmospheric details to be added yet... but I like to get the atmospherics worked out before adding detail. The glass panes are asymmetric double glazed as per engineering requirements for sound absorption - as in they are modelled to real life application.

However on the left side there are several trees that should be transferring shadows and images into the panels from outside - but the transparency is not high atm so thats why its extra odd that the sky would be appearing but not all that stuff being visible.

The sky should only be appearing as a very faint image on the panels where it gets transferred through the trees and a 'mute' panel behind that. IE that is where you set up a flat rectangle or other plane that sits between the sun and the scene with a texture or colour to act as a shadow layer/diffuser - a bit like the old photo vaseline layer smeared on the front of a camera lens.

After some more experiments with extreme and minimal settings the multiplier is not the culprit.

see here a reduced multiplier of 5.




Edited by nano
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Ok I think the problem is compound - kind of me expecting the environmental BK texture to lock to the horizon - which is not happening.

And also still not sure if it's sending the image texture direct through to the transparency layer somehow but I don't have the extra time to work it out.

I've tried mutliple ways to get it to work but I will just have to develop a better way to add image depth by building a material with the sky refections built in.

I tried a background sky panel but even with transparency and translucency I could not get the light levels to work for passing the other light effect through. it just lost all clarity and made it difficult to add other lighting and surface visual effects that I want in the image for other angles and times of day.

It doesn't seem to happen as much when a VRay generated sky is used. Also it could be the internal material light refraction and dispersal amplifying the effect.

Here's my last quick test to see the layers working...  before I go off and rebuild and add the sky reflection to the material.

It's a very subtle effect that I'm after.


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