Extremely slow render when using coronashadowcatcher

[Maybejensen]

Hey all, I'm currently doing my first "photomatch" job in corona render, previously i used to be a v-ray guy for this sort of stuff.
I find the coronashadowcatcher almost unusable, the rendering times are absolutely atrocious.
-I'm using perspective match on top of a photo to get the persepctive right.
-Then I'm putting the photo into this  material tree and applying to my geometry. https://postimg.cc/Mvd1V2F6
- I made sure to override the direct visibility to black, as mentioned in the shadowcatcher
- The initial render pass takes forever, 10+ min and rendering is then extremely slow
- Corona tonemapcontrol doesn't do much to the rendering time. I've tried bypassing it.

[Avi]

Hi,

Can you please send us your scene and a brief description of your issue in our support ticket here - https://corona-renderer.com/link/contact-support

Once we receive your scene through the ticket, we will investigate the issue and update you accordingly.

[shortcirkuit]

was this resolved?  im also having slow shadowcatcher render times

[Juraj]

It's probably the "compositing mode" For me it was always up to 10times slower than without.

Because it's so slow when I need only white-sweep, I rather use Distance map in opacity Slot of regular white material.
Of course, that doesn't help for true shadow-catcher need like this or automotive.

[Maybejensen]

It's probably the "compositing mode" For me it was always up to 10times slower than without.

Because it's so slow when I need only white-sweep, I rather use Distance map in opacity Slot of regular white material.
Of course, that doesn't help for true shadow-catcher need like this or automotive.

That's a pretty neat trick. I'll save it for later :)
I ended up modeling on top of the photo, then used projection mapping to get the image to wrap onto the geometry. This way it renders at normal speed and you get all the right reflections and shadows.
Might look a bit funky in the viewport, but it seems to work better for me.