Konzept Immobilien
Posts: 6
Joined: Thu 12 Nov 2020 13:38

Green Screen

Thu 12 Nov 2020 14:03

Hello folks,

we need certain parts of our picture to act like a 'green screen' so we can cut that part out / isolate it easily afterwards with photoshop.

The problem is: we can't find out how to make the shader to be not-reflecting at all. Please see the attached picture to understand what I mean. You see the color reflecting on all of the surrounding.

How would you suggest to deal with this task?

Thanks in advance for your advice!

Kenny
Attachments
Artlantis.jpg
Artlantis.jpg (309.68 KiB) Viewed 126 times

User avatar
CamilleSarrut
Posts: 730
Joined: Tue 20 Oct 2015 08:41

Re: Green Screen

Thu 12 Nov 2020 16:21

Hello,

I think you should set a white color instead of a pink one.
Then render an image in psd format.
In Photoshop you will be able to select the material in material layer and replace it with whatever you want.

Best regards,
Camille
Camille Sarrut
Abvent R&D

Konzept Immobilien
Posts: 6
Joined: Thu 12 Nov 2020 13:38

Re: Green Screen

Thu 12 Nov 2020 18:12

Well that would probably avoid the reflection or at least make it less obvious - but it also kind of defeats the purpose of a greeen screen. Using a 'white screen' you cannot select and cut the colour easily. It is supposed to be a colour that in the best case is nowhere else to be found in the picture. White stuff is everywhere.

Any other ideas?

User avatar
CamilleSarrut
Posts: 730
Joined: Tue 20 Oct 2015 08:41

Re: Green Screen

Fri 13 Nov 2020 09:09

You will select the material in photoshop in the Material layer whatever the color is.
Assigning a white color has just the purpose of limiting the impact on the rest of the image.
I don't know what you want to put in place of your green screen... but this is the way I would do it.
Here is an exemple with the material used as water in a swimming pool:

Material_Basic_on_surface_tobe_used_as_greenscreen.png
Material_Basic_on_surface_tobe_used_as_greenscreen.png (846.32 KiB) Viewed 108 times


Material selection in Material layer:

material_selected_in_psd_image_in_GIMP.png
material_selected_in_psd_image_in_GIMP.png (323.64 KiB) Viewed 108 times


Modification of the image using the selected material as mask:

image_modified_using_mask_from_material_selection.png
image_modified_using_mask_from_material_selection.png (841.35 KiB) Viewed 108 times


Hope this helps to understand.
Camille Sarrut
Abvent R&D

Konzept Immobilien
Posts: 6
Joined: Thu 12 Nov 2020 13:38

Re: Green Screen

Mon 16 Nov 2020 12:07

Hello Camille,

thanks for your reply.

I do understand what you mean and the way you postprocess the picture is the same as I do. We are in agreement there

But the example you chose is a very easy one. The pool is a simple geometrical shape. In fact it wouldn’t need a green screen at all. It is just one click in all four corners…done.

So please imagine your picture with the pool again, only with a small change:
Put a plant pot with white flowers before the pool.

Now it would be much more difficult to select white colour. Since you would have to look very closely to what is a just flower and what really is background of the „white pool“ shimmering through.

That is when you definetely need a different colour if you don’t want to end up with a lot of work.

Classicly it was a blue screen, nowerdays it is mostly a green screen, but it can be any rare colour. In my example above I chose pink since there are plants in the picture. So of course a green background would not be the best choice. I can tell photoshop now to select globally everything that is pink. And it doesn’t matter if it is a complex shape an there is pink shimmering through the bushes.

So I guess there is no way in artlantis to make a shader absolutely zero reflecting? That would be unfortunate. Then I would strongly suggest that as an improvement.

Or is there an option or another idea?

User avatar
CamilleSarrut
Posts: 730
Joined: Tue 20 Oct 2015 08:41

Re: Green Screen

Tue 17 Nov 2020 08:22

Hello,

If the material of the pool is only affected to this geometry, in Photoshop, you select by material so there is no problem selecting even if there is a plant in front.
It is Photoshop selection tool that does the trick.
In fact in my example there was some 3D grass on one side of the Pool and Photoshop created a mask around the grass blade.

Best regards,
Camille Sarrut
Abvent R&D

Konzept Immobilien
Posts: 6
Joined: Thu 12 Nov 2020 13:38

Re: Green Screen

Tue 17 Nov 2020 08:54

Hello Camille,

you are right, your example is good. I did not notice the grass line down there. So maybe I am actually wrong and I don't know about a certain feature of photoshop. Please help me to find out:

Please be so kind to cut out your selection, then put water in there instead (or just blue color to make it easier, is fine) and then please post this enlarged part of the grass line in high resolution.

If you are right, all the whiteish parts BETWEEN the grass blades will be also filled. If that is the case, please explain to me how to do that.
Attachments
partly-image_modified_using_mask_from_material_selection.png
partly-image_modified_using_mask_from_material_selection.png (21.34 KiB) Viewed 89 times

Konzept Immobilien
Posts: 6
Joined: Thu 12 Nov 2020 13:38

Re: Green Screen

Tue 17 Nov 2020 10:42

Hello Camille,

you are right! I just found out that I can render to PSD format! It is only now that I found that "material layer" that you mentioned! I alwas rendered to JPG and of course there is no layer there.

The material layer used as mask does the trick! I just did not get it at first.

Thanks for your patience and the advice that was correct from the beginning!

Kenny

User avatar
CamilleSarrut
Posts: 730
Joined: Tue 20 Oct 2015 08:41

Re: Green Screen

Tue 17 Nov 2020 10:54

Konzept Immobilien wrote:Hello Camille,

you are right! I just found out that I can render to PSD format! It is only now that I found that "material layer" that you mentioned! I alwas rendered to JPG and of course there is no layer there.

The material layer used as mask does the trick! I just did not get it at first.

Thanks for your patience and the advice that was correct from the beginning!

Kenny


Great !
Happy to hear that !!
Yes the advice was correct, maybe I did not insist enough on Artlantis Photoshop (psd) output format !!

Have a good day !
Camille Sarrut
Abvent R&D

Return to “Shaders & Textures”