Masking Question

[Paul Russam]

I've been successful using the AlphMask render setting in all but 1 situation ... where I have glass through which you can see the background.
Here's an example, this is a typical render, I have the spherical sky to produce the nice reflections in the glass but as there is no surrounding buildings I will cut out the background and replace it with a sky/white gradient.

Mask1.jpg (165.75 KiB) Viewed 9120 times

Here's the rendered Alpha mask:

Mask2.jpg (36.59 KiB) Viewed 9120 times

Here's the result of the Masking in Affinity Photo:

Mask3.jpg (159.51 KiB) Viewed 9120 times

AS you can see the background is still visible through the glass, It's a bit of a pig to select/erase in AP and the results are poor, to say the least.
Is there a method by which I can render an alternative to the Alpha or render a 3rd image that would enable me to mask the glass?
Ideally, I'd like to have the effect of the Skydome but without it rendering as a background in the saved image.

[Paul Russam]

Here's an example of a finished image with the sky/white gradient so you can see what I'm aiming for:

Mask4.jpg (161.05 KiB) Viewed 9118 times

[Fletch]

Why not just hide the glass and re-render the alpha mask?

[Chris]

Fletch's suggestion is the only way to accomplish what you are looking for. Unfortunately the result of that is you will end up masking out any reflections in the glass as well (at least in the areas with only "background" behind them). There is no easy way around it, unfortunately.

[Fletch]

You could try eliminating the spherical sky, and instead use a plane that is the treeline cutout to reflect in your windows.
Attempting to get the physical sky to look as close to the final sky you desire as possible.

[Paul Russam]

Thanks, There's only about 6 window types and 2/3 views that have the problem so I'll pop the glass on to its own layer, setup duplicate scenes sans glass and do an alpha render.
I'll post the results and method I use in Affinity Photo tomorrow.

[Paul Russam]

The Glass on a separate layer technique worked well, the lack of reflection in the masked area is completely unnoticeable.

Medium-04b:

Mask2a.jpg (181.38 KiB) Viewed 9088 times

Alpha (sans glass)

Mas2b.jpg (41.21 KiB) Viewed 9088 times

Post Affinity Designer:

Mask2c.jpg (184.79 KiB) Viewed 9088 times

All images via Layout PDF: https://1drv.ms/b/s!AmQX2TmhP_H6g804l21KbtGJGtMMMg

[Chris]