Compositing Tag - Compositing Background

[kromekat]

As title - much needed!!

Adam, ;)

[glass.use]

yes thats a great feature to be added to composting tag.
i think they will look into it ;)

[sunmade]

definately a must have!

[stefan]

yes i hope we can add that...
cheers
stefan

[jddog]

yes i hope we can add that...
cheers
stefan

I'm sure you will did it :D ... agree with kromekat

[Laurent]

funny how you think you've got a white background only to discover in photoshop that you're not done yet :?
Compositing to Background is really important for product shot.

[rikky]

I have been experimenting to try to create a work around until the composite background option is available in vray. I am not one of those who like compositing multiple passes and in c4d and vray and them ps them together. If I am using vray, I am using vray!

I created a plane for the ground (background). I then created a material and assigned it flat to the plane as follows:-

diffusion :-
RGB 0,0,0
Brightness 100% (doesnt really matter)
Trans amount: 0%

weight :-
Texture: Layer
Layer: Ambient occlussion
AO: Max ray length 10000cm (somthing bigger than your scene)
AO: Dispersion 0% (or 10% for softer shadow effect)
Invert the AO in the layer shader by right clicking the AO thumbnail and choosing 'Invert Image'

You should then be able to see your background through the plane, but the shadow should be cast.

Hope this helps someone for a work around solution. It is not an ideal solution. You can change the colour of the shadow by changing the colour of the white knot in the AO gradient bar. This is inversed so, for blue shadow you need to use yellow instead of white.

Here is a quick test scene, look on the ground for the shadow cast from the blue object. Lighting is provided through "very low" gi with grassy/tree scene as gi env mult x2 and also for background mult x1


http://img525.imageshack.us/img525/364/aoshadowtestft2.th.jpg (http://img525.imageshack.us/my.php?image=aoshadowtestft2.jpg)

[masgove]

Great job rikky!!!! But the shadow it's only perpendicular to the "X" world axis. :cry:
cheers

[rikky]

Great job rikky!!!! But the shadow it's only perpendicular to the "X" world axis. :cry:
cheers

I don't understand. I placed a plane below the item. (and also experimented casting onto side of a cube), and by moving the lights I changed the shadow position accordingly.

Maybe I not understand what you mean. Please explain and I will look into the exception.

[masgove]

In my experiment, when I move the lights, never changes! The shadows remain under the object and don't change position according the lights.

[rikky]

In my experiment, when I move the lights, never changes! The shadows remain under the object and don't change position according the lights.
I have just done some investigation and you are correct to some degree. One thing you must make sure is that the phong tag is removed from the geometry as this causes a few problems.

Another thing is that the effect seems to be reliant on the normal direction of the surface (which I think is what you were trying to say).
If you create a plane and set it to Z+ projection, then you can use a target tag to look at the light. This causes issue if you have multiple light sources.

This is a bit tricky for a complicated type of scene. But, the composite background function in C4D is pretty crude and therefore, this is probably just as basic as that one. It is only a workaround however.

HERE IS THE SAMPLE:
http://rapidshare.com/files/72594670/ao_shadow_solution2.c4d.html

[masgove]

Ok, this late afternoon I try and tell you the result.
THX

[rikky]

I have modified my previous post with the sample file.

[rikky]

MASGOVE - did you get any joy? :?:

I'm interested to know if this workaround is at least worth other people playing with. If it is not useful then it might be worth letting everyone know before anyone starts wasting their time with it. :cry:

[STRAT]

any update on this request Stefan? i too desperately need a shadow catcher for a luminance material, exactly as the AR tag works.

rikky, unfortunately i couldn't get much joy out of your solution either :(

[Laurent]

Please please please, for those of us that need it, composite to Bkgd is a must, I'm waisting so many hours trying to work around it....

[stefan]

at the monent vray has such a thing, we must ask valdo
cheers
stefan

[sunmade]

hi all, hi stefan and crew.

are there any news concerning the Compositing Background Option?

Has Vlado provided any feedback on the issue?

Thank you very much
regards
chris

[STRAT]

definitely second that.

we've just done a dvd over the last month that needed the comping tag. there was just no way around it in Vray so we use the AR instead.

shadow catching is absolutely essential.

(i know there's workarounds Stefan, but what a relief it would be :) )

[stefan]

such things arent made in such short time, thats needs core function changes. and vlado has also other nice vray he works on...

cheers
stefan

[sunmade]

Stefan, I thought you said a few post up that VRay already has such a function?!

So why the changes at the core?

thanks
chris

[stefan]

no the vray core has not such function, there some max scrips addons thatdo a similar function, but nothing in the core.

some matte functionality will come in new brdf material in next bigger update.

cheers
stefan

[kromekat]

Hey guys, are we any nearer to this?

Sadly VRay has been all but unusable to me pretty much since it's release, because of the large amount of product/conceptual stuff I have been doing, most of which requires the Compositing Background found in the AR tag, not to mention the additional functions that VRay hasn't got in it's Comp tag.

I know that VRay is very strong in other areas, particularly ArchVis, but it's GI and materials engine is so good for product/photo-real stuff, that it sickens me not being able to just make a simple unbiased choice of 'which engine for which job', when I have to always default to AR because of one tag! :]

Some of the new featurelist looks very impressive, and will undoubtedly open up the other uses I need covered, but please, if you can nudge Vlado in the direction of that one feature, I'd be grateful! :)

Adam

[shane]

no the vray core has not such function, there some max scrips addons thatdo a similar function, but nothing in the core.

some matte functionality will come in new brdf material in next bigger update.

cheers
stefan

Hi Stefan, Vray does have this option already. It has had it for quite some time. In Vray for max you can do it two different ways.

One way is using the material wrapper and checking the matte surface surface option and setting alpha contribution to -1.

Second way is to go into the vray properties (right click on object choose vray properties) for the object you want to be a shadow catcher and activate matte object and set alpha contribution to -1.

Here is a tutorial that shows how it is done in Max.

http://www.vrayelite.com/tractorcontent.php

-Shane

[stefan]

i know the max version, i also own max2009 and vray;-)

i said this is not in the vray core. this is an addon on the 3dmax plugin.
vlado made several max/ interface specific things that are not automatic in the sdk itself. many of those things we have to redo from scratch.

when we have it in the engine itself i am the first who want it added. many users ask for it.

it will come for sure, it is on the wishlist quite on top.

cheers
stefan

[STRAT]

it will come for sure, it is on the wishlist quite on top.

cheers
stefan

cool

[shane]

That is great news. When you said it was not in the core it made is sound like Vray was not capable of doing it. Thanks for the explanation, looking forward to this feature.

-Shane

[stefan]

well,
sure we read the wish lists;-)

i am sure we find a way to make this in c4d too. it is not in 1.1 though, just to make that clear. but as said i am aware many users wish this, so it will come.

cheers
stefan