Depth of Field / Camera Samples / Scene Scale

[infoMMJ2X]

Hi guys,

I'm new to Arnold/C4DtoA and I'm really liking it so far. The workflow and results are great. I've been learning a lot over the last couple weeks and have been doing my first project with it.

It involves rendering a scene with a pretty shallow Depth of Field, metallic objects with fairly complex geometry, SSS, displaced glass and some hair. I know this combination is hard for any renderer, so I'm not surprised I have to turn up the camera samples up quite high. I've read that 16 samples are quite usual for rendering with DoF. But to get a nice and clean render and clear the Bokehs of Noise I had to turn up to 20 Camera samples (rest of course at 1) and clamp at 1.5. Is this still within a reasonable range or might such high need of samples indicate that there is something wrong with my lighting setup for example?

Also one additional question regarding scene scale - my Project Scale in C4D is set to 1cm (so the standard sphere has radius of 100cm) and export scale is set to 0.01 (default) in Arnold. According my understanding of the manual this should result in correct scene scale for Arnold? I was wondering if there might be an issue because for the DoF I've had to use very low values - my aperture size is currently set at 0.005 which still results in pretty shallow DoF.

I'd be glad to get some pointers from some more experienced users so I'm not doing something wrong from the get go.

[lee_griggs]

Yes, you will need high Camera (AA) samples with shallow depth of field.

The low values could be an issue with your scene size. What happens to the depth of field when you change the Export scale?

[infoMMJ2X]

When I increase the Export scale to 1, the DoF gets a lot wider, resulting in a much sharper image at 0.005 - at the same time the scene gets considerably darker. My focus distance is at 65cm, so might that be a factor why I have to use such a small aperture value?

Because like I said, from what I understand in the manual my scaling settings should be right. Is there any definite way to determine this?

[lee_griggs]

Can you post a simple scene here to test?

[infoMMJ2X]

dof-scene-scale.zip

Hi Lee,

thanks for helping! I attached a simplified scene file for you. It's a tabletop, with some objects on it.

I also attached a quick render to show how it renders for me, with aperture 0.005. I feel that it's quite a shallow DoF for such a small value, but without physical camera properties it's kind of hard to judge wether that's supposed to be that way or if something is off with my scene scale.

dof-scene-scale.jpg

Thanks again!

[lee_griggs]

Yes, it does look like your scene is very small. I just created a default cube for comparison.

[infoMMJ2X]

Yes it is quite small, but the standard cube is 200cm on all sides, so the objects are still scaled correctly. Then I guess 0.005 is just a normal value for this type of scene/camera? Thanks for looking into it!