Problem with hdri background

[machteld_vanketwichverschuur]

Hi there,
I am working on a project of an apartment on the 5th floor. For the lighting I use an HDRI by Peter Guthrie in my Environment Material, so not a Dome Light. I set the image on Spherical on the Y axis. The glass material has All Channels on both in the Reflection and Refraction properties. In the attached images you can see a white groundplane which I cannot get rid of. With a scene on ground level this is not a problem, but this apartment is high up. You can see in the Alpha map that the glass balcony railing is taken into account. But when I apply this Alpha map the white groundplane become visible again in the image. I edited the HDRI in Photoshop to double downwards, but still the white plane remains visible.
How do I get rid of this white groundplane? Is it a setting? What am I doing wrong?
Thanks in advance for your tips.
Bye,
Mac van Ketwich

[larry.vasquez]

Does it do it if you have background unseen by camera?

[aleksandar.kasabov]

Hello machteld_vanketwichverschuur,

Could you please simplify the scene, then pack it and send it to us so we can have a look? You can send it by creating a support ticket via our contact form here.

Also, please make sure to mention this thread in the body of your ticket. Thank you.

[machteld_vanketwichverschuur]

Hi Guys, problem solved! So I read up about this problem and found out it had to be the Affect Channels/Alpha settings in the Reflection/Refractions properties of each Glass Material.

In this case:

We first have the window with its Glass Material. In the REFLECTION LAYER properties of this material the AFFECT CHANNELS = COLOR ONLY. In the REFRACTION LAYER properties of this material the AFFECT ALPHA = ALL CHANNELS.

Behind the window is the glass balcony fence with its Glass Material. In the REFLECTION LAYER properties of this material the AFFECT CHANNELS = COLOR&ALPHA. In the REFRACTION LAYER properties of this material the AFFECT ALPHA = COLOR&ALPHA.

See attached screenshots.

The Alpha Map is correct now, it shows the plants between the Glass Windows and the Glass Balcony railing. Also the Balcony Railing has a correct Alpha Map, it is a bit less transparent then the Glass Windows as you can see.

Hope this helps for others who have been struggling with this.

[larry.vasquez]

Thanks Machteld. That's good to know.