How to make object 'unseen by camera' ?

[rojharris]

Hi. I am running the demo and have hit a stumbling block. How do I make an object invisible to the camera? I want to make a reflection panel but don't want it showing up in renders?

Thanks
Roger

[Micha_cg]

Re: How to make object 'unseen by camera' ?

http://asgvis.com/index.php?option=c...18836#msg18836

I hope, Joe will find a way to implement it soon.

[merlik585]

Re: How to make object 'unseen by camera' ?

Or you can use a 2 sided materials,the side facing the camera transparent material,and the other whatever material you want.

Renee

[dalomar_cg]

Re: How to make object 'unseen by camera' ?

I was wondering if anyone else would throw that one out there...Good catch Renee...There are some things about that setup that cause a little hiccup in the system though (not really sure what they are, but any way)...certain light (only direct light I think) and object reflections will always be calculated by using the material that is applied to the front side of the material. The backside material will only be used for diffuse/GI calculations. This means that you can play some tricks with things just by switching around which material is on the front and which one is on the back.

[Micha_cg]

Re: How to make object 'unseen by camera' ?

Or you can use a 2 sided materials,the side facing the camera transparent material,and the other whatever material you want.

Renee

Dosn't work, if you need the front side of an object visible for reflection and invisible for camera.

damien, I want to be sure - I mean simple options like shown at this thread (screenshots from AIR and Maxwell):

http://asgvis.com/index.php?option=c...14827#msg14827

and I don't mean a complex exclude/include manager for single objects. Doe's the SDK not support a simple code for tag objects or materials?

[dalomar_cg]

Re: How to make object 'unseen by camera' ?

Micha,

By placing a given material on the front or the back side of material you can fake a few things...But the downfall is that each situation will have some side effects...

Here's a render of what I'm talking about... 2 exploded boxes with their normals facing inwards, and two chrome spheres in the middle of them. The one on the left has the brick texture as the front material and "nothing" on the back, and you can see that its not visible to the camera and that light calculations take the brick (front) material into account...the box on the right has the "nothing" material on the front and the brick material on the back; reflections and light calcs take the front material into account, but the geometry is visible.

The rendering...


Then normals (so you believe me ;D)


I'm not discounting the wish, and believe me I want it as much as you. But its not just as simple as it sounds, or else Joe would put it in there. Even the simple thing of the Material include/exclude everything for reflections have taken a lot to get working well.

[Micha_cg]

Re: How to make object 'unseen by camera' ?

Thank you Damien, it works great. Attached the first invisible for camera emitter with reflections at VfR. ;D

[Micha_cg]

Re: How to make object 'unseen by camera' ?

... it works for reflection, refraction and diffuse materials. Attached an example with two invisible emitter materials and an invisible ground (right image).

[merlik585]

Re: How to make object 'unseen by camera' ?

I was wondering why you were saying it did not work,I used that trick all the time,in various situation,if you don't need a box,but just a flat panel it is even easier.

Of course if the shadows could be disable per object it would be very useful.

Renee

[han3d]

Re: How to make object 'unseen by camera' ?

can anyone put their material settings' screenshots

[Micha_cg]

Re: How to make object 'unseen by camera' ?

Create a new "VraySkp2SidedMtl" (horrible name) and a material like you want for the hidden object ...

[han3d]

Re: How to make object 'unseen by camera' ?

thanks micha

[Micha_cg]

Re: How to make object 'unseen by camera' ?

I found, that this effect - light is send from the invisible side and the invisibe surface is seen at reflections - is only available, if the material is assigned to "Front" the VraySkp2SidedMtl. If "Back" is used instead (and the normals of the surface are flipped), than it dosn't work. So, it's not the same to use the material at "Back" or "Front2 only.
That's important for rendering closed rooms and the camera looks through the wall from outside. If the material is assigned to "Back", than lights from outside comes through the wall, if the material is assigned to the "Front", than no lights come through the invisible wall. I think, both effects are interesting.

[Micha_cg]

Re: How to make object 'unseen by camera' ?

Also good to know - this kind of invisible wall block the z-depth calcualation.

Stay to hope, that the invisible wall trick isn't needed in the near future, if the object based properties are implemented and the user can choose between different visibility options.

[dalomar_cg]

Re: How to make object 'unseen by camera' ?

It shouldn't be...Per Object Properties are on their way and should be one of the things you'll see in the first rounds of development.