Shadow Catcher too big!

[danjames66]

Hey folks,

I normally do well to find my answer through the forum, but I'm struggling on this occasion.

A new to me tool is Shadowcatcher. Whilst I've played with it before, I've never had any need to put it into practice until now.

I'm trying to create a series of product images (png) that have a small, concise shadow beneath, which seemed simple on face value.

Now I'm at the output render stage, I've realised I'm not getting the desired results (see attached).

I'm getting a large graduated shadow which, when dropped onto a which background, creates hard edges to the image.

Is there a way to limit the amount of shadow produced. I've tried playing with reflections and GI, but nothing appears to work.

Any help would be most welcome.

[maru]

Sorry for the lack of response here. If it's still valid, can you explain how exactly you end up with that "wrong" image? Does it render like this, or is this after compositing with alpha channel?
Also, have you tried adjusting the "shadow amount" value in the Shadowcatcher Mtl?

[danjames66]

Hi Maru - Thanks for replying.

So the 'Wrong' image is directly rendered.

I've tried changing the way the scene is illuminated (HDRI to achieve a studio look).

I've done some digging since and concluded that this is beyond the ability of Corona, whilst vray is able.

If you have any suggestions, I'd love to try them.

I had to manually edit shadows in Photoshop after the event, which was painful.

[Aram Avetisyan]

Hi Maru - Thanks for replying.

So the 'Wrong' image is directly rendered.

I've tried changing the way the scene is illuminated (HDRI to achieve a studio look).

I've done some digging since and concluded that this is beyond the ability of Corona, whilst vray is able.

If you have any suggestions, I'd love to try them.

I had to manually edit shadows in Photoshop after the event, which was painful.

Hi,

I think you have done everything right, you just expect to see the shadows in a different way, while in reality the shadows are/should be as rendered.
I don't think this is anything about what Corona or VRay can (not) do. It is a matter of lighting/compositing the scene in a way to get the desired results.

Can you please show how it looks for you in VRay, and what is the setup?
A scene will be appreciated of course, to check.

[Digital Esthetics]

Hi. I have had the exact same problem and solved it.
1. Don't use HDRI map. It gives you bigger shadows that bleeds out.
2. Shadow catcher has to be on composition mode. And lower the shadow.
3. Put the shadow catcher into a ray switch and leave the vi slot blank.
4. Use lights instead of HDRI. And one lamp from above that is only a shadow catcher illuminator l. This light will create the shadow. All other will exclude the plane with the shadow catcher.
5. In the scene överide use to mapping control and whatever color you want if you want pure white color. Fick off all options.

What you will get is a cleaner image transparent or not buy without bleeding shadows.

Let me know how it goes

[maru]

You could also try using the "for compositing" mode of shadowcatcher and adjusting the alpha mask in post (making the darkest areas even darker, to get rid of the parts of the mas you don't want to see).

[danjames66]

Thanks for both your replies. I'm currently stacked with work, so opportunities for research are few and far between.

Regarding my mention of a tool gap between vray and Corona. The effect I'm looking for is the equivalent of using a vray plane and switching the matte object properties on (as per Chaos instructions for shadow catcher). The shadows are much more localised and don't bleed across the frame as they do in Corona with Shadow Catcher.

I'll give the suggested method from Digital Esthetics a try and see if I can get similar results.