here an example of why i am forced to keep using vray ...

[xtrm3d]

hi ,
here is an example of why i am still forced to use vray .,..
i really hope that a dev could chime in .. and may be give me some hope ..

her two picture .. first one with vray ,,,
around 45 mn !! render time
enviro sphere lighting
and background image with screen space projection


then the one in octane
just shy of 5 mn !! render time
enviro sphere lighting and enviro sphere as backdrop



main issues

- in vray , i can have my shadow catcher also be able to catch reflection .. not possible in octane and dearly needed
- in octane .. the shadow catcher is never fully transparent .. see red arrow .. yes i did turn on importance sampling ..
if i turn it off the effect is more pronounced .. but it never go fully away when i turn it on
i was never able to get a clean shadow plane out of octane . ( am i maybe missing something )

in octane ..
i cannot assign a background plate like in vray
you would tell me that i could do it in photoshop ...
yes..but...
very annoying since i do my color grading in octane .. and i would need the plate to receive the same treatment

it is very late in at night right now.., and i hope that i still make sense

thank you for any input that would still give me hope

[xtrm3d]

here i an example of the alpha from teh ""shadow catcher ""
as you can see it's totally wrong
and yes importance sampling is turned on

[xtrm3d]

more than 150 views and zero response ...
am i the only one that have the shadow catcher visibility problem ?? ..
or that is bothered by the lack of reflection catching ?

here another one that i did let cook longer.. as you can see the effect is still there .. it's subtle.. but still there




can we hope to get this issue solved soon ?
and may be getting some reflection option ?

[FrankPooleFloating]

Probably not the exact answer you desire, but in this situation I would hit the ground plane/shadow catcher with a UV and make an opacity map that fades off about 6 feet around rectangle (car bottom) in all directions... I've had a couple renders that this worked well for. Even with reflections + shadows on a semi-glossy plane with bumps. And now with visibility, I would do this as a separate render with car invisible to make it even more tweakable.

[roeland]

There are a couple of problems here, first a reflection catcher is a much more advanced feature than a shadow catcher. To do this with a current version of Octane you would have to make two renders of the plane, one with only the plane and one with the plane plus the car, and then, in the areas where the plane is visible, you can calculate the difference between these two renders, and add this difference to the background image. This is possible in Photoshop but it is quite complicated to get right.

The reason why the shadow catcher never becomes fully transparent is because it takes into account all light sources in the scene, including the head lights of the car. So you always get some shadow from the head lights in most places. I don't know why you also get noise where the environment is visible, this area should always be fully transparent.

Unfortunately the solution is not going to come soon, we are already busy with quite a bit of other things now. But you can use some workarounds as mentioned by FrankPooleFloating.

--
Roeland

[xtrm3d]

@FrankPooleFloating
thank you very much for stopping by and giving some idea ..
i would love to see some of your result .. any chance to point me to them ? or may be post them here ?

i kind of like your work around ... only stuff that bog my mind.. is how do you deal with the projection on the floor ?
i mean .. you would want it to conform to the enviro sphere or teh back plate .. right ? or do you just create a completly different looking texture that you try to blend with the transparency fallof ?

thanks !!


@roeland
""There are a couple of problems here, first a reflection catcher is a much more advanced feature than a shadow catcher""

hehe .. you give me a finger and i want the whole arm .. more feature you give us.. and more we would want

as for your solution ,
i could make work with some mask generated in octane .. that should work ..
although i am no sure that the maya plugin is up to date and and include the visibility raytrace features

""I don't know why you also get noise where the environment is visible, this area should always be fully transparent.""
neither do i .. ... i always have this issue in maya

""Unfortunately the solution is not going to come soon, we are already busy with quite a bit of other things now""
looking forward to it , would enjoy them .. and then would complaint and ask for more features

thanks again to both of you guys

christophe

[FrankPooleFloating]

I'm sorry christophe, but unfortunately none of my commercial work can be posted. Very strict NDA with all three of my clients... and only a slice of my work is ever seen by the general public. We will just leave it there.

Really, just do a plane with UV and opacity mask and do a shadow pass and a reflection pass with car invisible... composite and twerk as needed.

Guys, help the bro a little, beyond what I said...