aiImage Start Channel & Single Channel

[Anonymous]

Arnold aiImage Start Channel & Single Channel ?
I was hopping the aiImage can load multi EXR channel, So I did 5 HDRI images in one single file multiEXR
trying to load them (for lookDev) by typing the corresponding number(1-2-3-4-5), Unfortunately does not work! So I did another test with simple png file and another with jpeg file

For png file(red flower)
0 = default(beauty)
1 = Blue
2 = Blue for the Alpha and cyan for the color
3= White for the color and cyan for the Alpha
For Jpeg (red and yellow texture)
0= the same default
1 = the red becomes Blue, yellow becomes Magenta, and white becomes yellow.
2 = the red and yellow becomes cyan and white becomes magenta.
3 = the white becomes cyan, red and yellow become white.
another test with rendered image (multiEXR), give an interesting result, but it does not match the aov stored in file texture.
here is a link to a video showing the problem:

https://youtu.be/KFXOL6AG-io
what is the math behind this?

[Anonymous]

start-channel-12-aiimage.pngseparate-renders.jpegstart-channel-4-aiimage.pngstart-channel-8-aiimage.png

Very interesting topic. I dont know how many users are there for this technique, But this is a unique way of using in Lookdev. Salute to you that you wanna use this method.

I have my method elaborated in those attachment images.

First I combined all my .hdrs files in nuke through the Shuffle Copy node and rendered to exr.

Now I called the .exr file through aiImage and connected to my skydome.

You can see Start Channel 0 renders the exr 0 RGBA channel.

Then Start Channel 4 my HDR1, 8: HDR2 and 12:HDR3. In-between SC numbers are for separate HDR1-R, HDR1-G, HDR1-B.

Here the link for whole setup for better understanding.

https://drive.google.com/file/d/1Cg2OauF-HBqZz5B3giTp4m4wlMaaG3xs/view?usp=sharing

I love the aiImage node. Arnold is way better comparison to other rendering methods.

[Anonymous]

Ah, So the forth first number (counting from zero) correspond to RGBA, really nice, that fix the problem.
Hope the team at SolidAngle can perform the aiImage and make it more flexible, by adding Start Layer, that detect all the layers like LayerContactSheet in Nuke.

[Anonymous]

If i am correct thts not an issue.

Usually in programming languages c++, python take 0 as 1st and 1 as second so on.

[Anonymous]

Really cool we can use 51 HDRI image in one single file, in the past I was using "aiSwitchRgba", to switch between 18 files, that mean you have to load 18 HDRI in memory, I prefer one single file with aiImage, you have the ability to do some exposure directly with Multiply and offset, without another Color Correct node, also you can use balk & white with Single Channel.
this node aiImage need to have also Start Layer