Corona Shadow Catcher for interior

[edoardo_explorer]

Hello!

I'm working on an interior scene: I have to add some furniture on an photograph of a palace room.
So the plan was to model just the furniture and use Corona Shadow Catcher to project the shadows on the photograph.

I built the room and applied the Shadow Catcher material used as backplate, added a Sky and a Sun, but the geometry of the room doesn't affect the shadows.
I supposed that if a material has SC material doesnt' project shadows, so I tried to duplicate the room and add a compositing but the situation doesn't change.

How can i fix it?

There is other ways to render just the furniture and the shadows?
I read that shadows channel just let you lighten the shadows.

Thanks

[jojorender]

Did you find a way to do it? If so, please share.
Not sure if there is a “right” way to do it, but I also roughly build the room and apply SC mat.
For lighting I use, basically the extreme old skool way of lighting a room - area light in front of windows. Corona lights with SC illuminator ticked on.
Agreed, that can’t be the right way, but it kinda works if you have highly diffused light.
Would be cool if the corona team can offer some help.

[edoardo_explorer]

Hi Jojorender,

I asked to the Corona Help Center.
They fixed my file applying SC material to floor and walls and removing it from the ceiling so it can ben considered for GI.
The problem, I think, is that there is no way to avoid overall lighting/shadowing to an entire with shadows.

Attached their test image.

I think the only way is to render the furniture without using SC and then mask them with mask ID in photoshop, and manually add shadows and reflections on the floor.
But I don't know if there is a way to export just shadows and reflections ready to use.

I thought to render the room in white and put it in multiply but, again, there will be an overall shadowing on the entire floor!

Thanks

[jojorender]

… render the furniture without using SC and then mask them with mask ID in photoshop, and manually add shadows and reflections on the floor.
But I don't know if there is a way to export just shadows and reflections ready to use.

What a nightmare. Can you imagine any revisions and then constantly photoshopping previews…NO, THANK YOU!
I tried shadow multipass, but I can’t get anything useful.

So they used sun and sky to light this scene? Is the red circled part a shadow from the new chair or already in the original image?
What are all these ghosty layers green circled? If this is what they got out of the VFB, it still needs a ton of photoshop.

While exterior shadow catch works OK, the interior part….well, could be better.
Virtual staging is pretty big in the nyc real estate market and you see a few good examples but a lot more horrible, generic light images that should not exists.
I guess most virtual stagers don’t use corona or found some workarounds.

[edoardo_explorer]

Yes, they used sun and sky I put in the scene to simulate the real light coming through the windows in the photo.

The red circled part is shadow from the new armchair (because floor and walls are SC, only the ceiling is an object without SC) and the green circled are areas where the new shadows from the ceiling ovelaps the existing shadows of the photo.

So basically shadows of the room are doubled. But this time shadows of the ceiling only.

I really don't know how virtual stagers can do it easily!
A way could be use a 360° hdri of the space, give the SC to the entire model, so the room should not be affected by the light and the armchair is light correctly.

But if you don't have a 360° I don't know if it's possible

[jojorender]

A way could be use a 360° hdri of the space, give the SC to the entire model, so the room should not be affected by the light and the armchair is light correctly.

Not sure I understand what you mean. Wouldn’t that be the same as sun & sky?
The 360 just for lighting, since you still need the room geo to catch the shadow on floor, walls, etc..
Anyways, all requests I’ve ever gotten for virtual staging had all regular 2D images…

[edoardo_explorer]

I thought that 360 provide the same light of the room geometry (maybe because it emits only where should be the windows??) and the entire room, with a SC material, just catches shadows and don't generate GI.

Anyway Corona support stop answering me.
Maybe there's no solution 😅

[TomG]

Not sure what you mean by stopped answering you - was there a ticket number, where you are not receiving any replies? Thanks!

[CambridgeCreative]

Have you thought about applying the background photo onto your CGI model of the room using a corona material with frontal projection? If the camera is setup so your CGI model matches the room in the photo, and you recreate light placements as in the photo, i can only imagine you will get a decent result. I tend to only use shadow catcher materials on ground planes for product visualisations on white backgrounds or where I know the shadows won't cast onto walls and furniture in a room.

[BigAl3D]

Another tip is to use a disc object centered under the chair, but large enough to cover any shadows. Apply the Shadow Catcher material to that abject. In this way, it avoid adding any extra shadows around the room as using the entire floor would do. I have also added an Opacity Map to the SC to further limit and soften the shadows should they creep too far from the disc object.

You can also render so that your chair is output with the shadow all in one file (See attachment. You'll have to download it to see). If you have several shots set up in that same angle, you can just drop that file onto the other images and it will be ready to go. You can slide the chair a bit along the wall after the render. Same process could be added to the wall near the chair so there is a shadow behind the chair. Yes, I realize this isn't a super flexible solution, but easier to deal with one piece.

One limitation is that the shadows that are captured do not show any geometry bumps that may be present in the floor, just smooth shadow which may or may not be a problem.

[burnin]

in the old days, Ambient occlusion sufficed, and most of the time still does ;)

[edoardo_explorer]

Have you thought about applying the background photo onto your CGI model of the room using a corona material with frontal projection? If the camera is setup so your CGI model matches the room in the photo, and you recreate light placements as in the photo, i can only imagine you will get a decent result. I tend to only use shadow catcher materials on ground planes for product visualisations on white backgrounds or where I know the shadows won't cast onto walls and furniture in a room.

Hi CambridgeCreative,
I think that in this way the walls create anyway a shadow on the floor and walls that already exists in the original photo/material.

Yep, shadow catcher works well with open spaces and product visualisations

[edoardo_explorer]

Not sure what you mean by stopped answering you - was there a ticket number, where you are not receiving any replies? Thanks!

Hi TomG, no he didn't stop answering me.
He was trying different solutions, he came back to me with some alternatives!

[edoardo_explorer]

Another tip is to use a disc object centered under the chair, but large enough to cover any shadows. Apply the Shadow Catcher material to that abject. In this way, it avoid adding any extra shadows around the room as using the entire floor would do. I have also added an Opacity Map to the SC to further limit and soften the shadows should they creep too far from the disc object.

You can also render so that your chair is output with the shadow all in one file (See attachment. You'll have to download it to see). If you have several shots set up in that same angle, you can just drop that file onto the other images and it will be ready to go. You can slide the chair a bit along the wall after the render. Same process could be added to the wall near the chair so there is a shadow behind the chair. Yes, I realize this isn't a super flexible solution, but easier to deal with one piece.

One limitation is that the shadows that are captured do not show any geometry bumps that may be present in the floor, just smooth shadow which may or may not be a problem.

Hi BigAl3D,
yes use a disc object could be a solution to reduce the visible shadows, but in my case I think that the shadows of wall will be seen anyway.

I was trying to achieve the same result of the car you attached. How did you do it? Is it a set (curved floor+wall) with a Shadow catcher material?
But my doubt was to obtain masked furniture+shadow but with a light coherent with the light of the room.
Maybe a simple area light from the left?

[edoardo_explorer]

in the old days, Ambient occlusion sufficed, and most of the time still does ;)

Hi burnin,

I'm not sure I understood!
I mean, I can do it in photoshop, with a brush to simulate shadows, but for complex scene I think it's a little tricky.