I’m in this position a lot where my clients want images and video assets with transparent background and alpha.
The shadow catcher works really well if they just need shadows. I can render out a shadow and works with alpha. .
However when it comes to reflections this is where things get tricky. As I ultimately need the reflection to be alpha.
If I were compositing onto backgrounds I could use the reflection pass… and use ADD mode or whatever. This does not work well on white background as you’d imagine. Also it’s not an alpha so I can’t give that to my client in this way.
This is relatively simple if it’s an image, but takes some work so not ideal. But for animation sequences it’s next to impossible.
I’ve even looked at hacky method such as duplicating the object or creating an instance, then minus that by -1 on the Y axis. However you do not get the ability to adjust roughness or have it react to different material conditions, it’s basically a mirror.
First of all, does anyone have any tricks to achieve this?.
But then to octane devs can we not have a reflection catcher function or pass. I believe in Redshift you can allow the reflection to contribute to the alpha. Seems limited to only render reflection pass onto black background as you are forced to use blending mode which in post causes limitations on BG.
I’ve spent weeks on this problem spread over various projects. I’m even learning redshift on the side but Octane is still my main renderer at the moment as I only have limited downtime.
I literally have 3 projects at the moment requiring me to do this so it’s pretty insane that it’s causing me such pain when it’s such a common thing for product imagery.