Turning on alpha does not turn on alpha

[hdace]

I have an interior tracking shot that begins with a wall in the background but then passes a window. The window uses specular material with fake shadows and affect alpha. Path Tracing kernel has alpha turned on. And yet, there is no alpha channel in any of the png image files until the window appears. Then, magically, there is an alpha channel!

I know that if the previous files had alpha it would be all white and a big waste of data on my hard drive. But it's my hard drive and I want to waste its space. Because it's extra work setting up After Effects. How is AE supposed to know an image sequence includes an alpha channel if the initial files don't have one?

[juanjgon]

Yes, I can see the problem here. Perhaps using the EXR file format you could avoid this issue. I will send it to the Octane developers.

-Juanjo

[hdace]

Okay, thanks!

[juanjgon]

This problem seems a limitation of the third party library used by Octane to manage the image files. When this library try to save an image with a full opaque alpha channel, the PNG file is saved in 24 bits, and this is not configurable.

Have you tried to work using the EXR file format?

-Juanjo

[hdace]

Okay. Yes I've used EXR. No problem. Thanks for looking into it.