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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.

Hi,
in OctaneRender you need to use the Render Layer passes:
https://docs.otoy.com/StandaloneH_STA/S ... Passes.htm

ciao,
Beppe

bepeg4d wrote:Hi,
in OctaneRender you need to use the Render Layer passes:
https://docs.otoy.com/StandaloneH_STA/S ... Passes.htm

ciao,
Beppe

Hi Bepeg, I don't think you understand what I'm asking for. I'm fully aware of AOV's and use them every day, but they require you to render out on black and depend on blending modes, this doesn't work well on solid backgrounds. Even the layer reflections AOV. The only thing you can render directly to an alpha channel is a shadow using the shadow catcher material.

I've been learning Redshift over the weekend and it's incredibly simple to do what I'm asking. You can literally add the reflection to the shadow catcher material and you've instantly got an alpha reflection that works perfectly on both black and white solid background.You can even add bump maps and roughness and this all affects the alpha channel too..(it's mind-blowing how easy it is)



Like I said in my original post, my clients need assets on a clean transparent background. It's not that crazy of a request, but it causes me heaps of photoshop work.

Just look at the difference between the Redshift shadow catcher and the Octane one...Octane is literally just a single checkbox in the common tab of diffuse material..Hardly has much option to adjust.. Redshift shadow cacther is extensive tool, as you can see in above screenshot.

This would be a great feature--it's really a pain in that ass that this doesn't exist as a pass. I'm always having to manually create this pass via custom materials, to get a proper masked/transparent reflection.

itsallgoode9 wrote:This would be a great feature--it's really a pain in that ass that this doesn't exist as a pass. I'm always having to manually create this pass via custom materials, to get a proper masked/transparent reflection.

They just need to work on the shadow catcher as a whole and add a lot more functionality to it. Its current form is pathetic single checkbox.

Yes please, +1 for a simple reflection alpha solution!

+1

+10000

every time I work with Octane I'm impressed with how responsive and fast it is, only to have to waste hours and hours of time for workarounds such as for this kind of a case, it's infuriating

This would really be a game changer, it's a huge frustration for me...

Please have a look at what you can do with Custom AOVs:
https://docs.otoy.com/cinema4d/CustomAOVs.html

ciao,
Beppe