Coloured Glass Issue With Alpha Channel Tweet

[GIOLETS]

Well I've investigate a little bit and I've found that also with the Bepeg4d solution the background image don't fit exactly the screen.

I've found a solution that it's really "dirt", tweaking a lot on 3d transformation value, so I ask if is possible that someone of the Octane Guru can publish an "How to do " guide, because as I wrote before, every day, expecially doing architecture rendering, we have to put a background image under windows or balcony glass railing, or simply viewing post effects of a light street ...

[bepeg4d]

Hi Luca,
oops, sorry, probably I've skipped your posts.
The key is to use negative scale instead of rotation.
Please, share with me an example of one of your everyday scene with your common settings (film buffer, camera, ecc).
Happy GPU Rendering

ciao beppe

[GIOLETS]

Hi Bepeg4d,
thanks for your help.

Here you can find the scene: that have only 2 environment objcets (one for lighting, one for backplate, reflection, etc).

The goal is to fit exaclty in the screen the background image.

Thanks again.

background.rar

(4.61 MiB) Downloaded 207 times

[bepeg4d]

Hi Luca,
please, have a look at screenshot and attached scene:

background_b.c4d.zip

(42.91 KiB) Downloaded 207 times

1. change the Border mode to Black or White to better see the end of the image.
2. use the Film Aspect value in the S.X value of the Perspective Transform node.
3. set the rotation in this way:
R.X = -R.P
R.Y = 180°- R.H
R.Z = R.B
4. set the S.Z zoom factor, but I cannot explain why it works with 2.432, sorry

Please, try with another of your scene to see if this method is working.
ciao beppe

[GIOLETS]

Fantastic,
I'll make some test and let you know.

Thanks a lot.
If if works should be placed on the "How to..." zone.

Grazie mille.

Luca

[GIOLETS]

Another school work for the holiday...

I've tested with another scene, and it works.

background 2.rar

(13.78 MiB) Downloaded 232 times

The only note that I'd wish you to check:

RX= always invert the positive to negative value and vice versa.
RY= always positive

SZ (zoom factor) in that case is 1.83 seems to depend not to the camera position but is in raltionship with the lens (or the field of view) used.

TY (or TX) = to use if the camera have an Y or X offset (in my case I have a 5% Y offset so I've manually found -0.045 value , that is about 5/100 infact)

Wow.. not easy.
Would be fantastic to have a script that do in automatic way all this operation. As I said doing architectural rendering you have every day to manage the background image...

Thanks for your help. Ciao.