Shadowcatcher artefacts

[sprayer]

sharing the scene will be faster to solve this

[build]

Sure. Here you are.
http://ge.tt/1SaUNCx2

[Frood]

After opening the file, I noticed this scene has over 2000 animation layers. Merging anything of it into another scene will also merge those (global tracks) to the new scene.

You should generally use a cleaning script to avoid pollution of your scenes ("cleaner" script for example or - specifically for animation layers - this one: https://forum.corona-renderer.com/index.php?topic=17011.msg106638#msg106638 which does a check automatically when opening a scene.)


Good Luck

[build]

Found them. Thank you.

[sprayer]

Scene not good setup,but whose circles in alpha because you checked illuminator in light settings

[build]

You mean the lights on the right and on the left? Those are not supposed to cast any shadows. That's why they are just illuminators. When I disable the illuminator function the shadows they cast will extend the shadows to image borders which will give me a visible edge which I don't want. Also, they will create a "shadow noise" which I mentioned before.

[sprayer]

this check box not for casting shadows,it for casting light on shadowcatcher object, shadow catcher is catching the shadows but this checkbox gives you option to catch the light on shadowcatcher for  example you need to light photo background with pasted corona light in scene(not only shadows from it). Your scene not need this. To remove shadows you need other methods, for example standard light may not cast shadows, but i think it better to setup proper lights with studio hdri with soft light.

This is lights with only one studio hdri

and a bit adjust in output curves

by the way you have also exposure control enabled in environments

[build]

this check box not for casting shadows,it for casting light on shadowcatcher object, shadow catcher is catching the shadows but this checkbox gives you option to catch the light on shadowcatcher for  example you need to light photo background with pasted corona light in scene(not only shadows from it). Your scene not need this.

Thanks for this. It gives me indeed a better understanding. But still, I have the problem with the transparency of the shadowcatcher material. It would like to know how your image behaves if you would save it with a transparent background. I am sure you will still have a lot of noise from the shadow around the table. And this is what I am trying to avoid but it seems there is no way to do so in corona. For me, this is a bug in the software...