No Alpha channel to be rendered out

[Ron]

Just a quick one:

when doing an interior shot with outside view through the windows I can't get an alpha channel to be rendered out (to bring in the background in PS). I tried a lot of settings and tweaks but without success. Only disabling the glass leads to the desired result with an alpha channel - of course without reflection in windows

Can someone help?

Thanks - Ron

[FooZe]

Hi Ron,

The best option here is to use the "glass fake falloff" material in the LiveDB (In Materials->Non-Organic->Glass).
Use a single plane for the window and apply this material.

It is a glossy material, with no diffuse, full specular/reflection and a falloff map for opacity.
This means it will be see through at straight on angles and show the reflection at glancing angles.
You can tweak the falloff map to suit how much reflection you want.


Hope that helps.

Thanks
Chris.

[Ron]

Hi Ron,

The best option here is to use the "glass fake falloff" material in the LiveDB (In Materials->Non-Organic->Glass).
Use a single plane for the window and apply this material.

It is a glossy material, with no diffuse, full specular/reflection and a falloff map for opacity.
This means it will be see through at straight on angles and show the reflection at glancing angles.
You can tweak the falloff map to suit how much reflection you want.


Hope that helps.

Thanks
Chris.

Thanks a lot Chris! That is what I was looking for. Maybe you can help with another issue, too? Is there a way to exclude objects from AO like you can with the render tag? I have a cupboard with translucent glass doors (objects inside should be shining through) that turn out black because the AO value which is at 5 to give better results for the entire room. Turning down to low values helps but affects the rest of the image in an undesirable way. I still tried to use an octane object tag with shadows off but that did not help yet.

Thanks again - Ron

[FooZe]

Hi Ron,

No. There is no way to isolate the AO effect for one object.
The shadows tag means that the object will not cast shadows.

Your problem with the cupboard with glass doors might be related to the fact that and light that goes through glass is generally classed as a caustic and is therefore hard to "clean up" during render. Direct light onto things is far quicker to resolve and won't need PT or PMC as much. What you can do is try the "fake shadows" option for the cabinet glass.
What this does is let light go through without needing the complex caustic calculations, so it will work well for AO and should let light get to the cupboards 'cells' easily.

Also make sure you have a high enough specular depth or you will get blackness behind glass.

Let me know how it goes.

Thanks
Chris.

[Ron]

Hey Chris,

thanks for that awsome tip! Now the glas doors look like they should - things inside are shining trough and the render time is definitely faster. Octane is amazing and I am learning every day someting new about it. Great!

Cheers - Ron