Physically inaccurate DOF

[scottwadd]

I understand how to use the physical camera depth of field, but how do you override your camera depth of field to make your scene look like a tiny-town without scaling down the scene? Thanks!

[mattclayton]

I'm not a 100% sure on this but you might try playing with the vertical tilt/shift on the physical camera to alter the angle of the plane at which your focus DOF works. As i understand it in real world term it's this effect from tilt-shift lenses that creates the miniature look.

There's an article here about half way down that describes how miniturisation occurs in photography. http://cow.mooh.org/projects/tiltshi...oesitwork.html

As i said, i'm not sure if the same will work with the vray physical cam though. Let us know if it does work!

[Neilg]

use the depth of field in the render settings instead of the cam, or switch off exposure in the camera and make the aperture 10-50x the size.

[Streetwise]

I don't think you can pull off the same effect with the v-ray camera as you can with a physical tilt-shift lens setup. The Vray camera has no way to tilt the lens. Instead, it can only tilt the vertical plane of the camera. This is something I've wished for is to have a camera that works just like a view camera where you can tilt both lens and camera plane separately on both axis.

[scottwadd]

NeilG, I tried enlarging the aperture to achieve that, down to 0.025 for my scene. The camera's focus range planes show up, but they don't seem to have an effect. (I can get DOF working fine when using a real world aperture and short distances, though, so I'm not forgetting to turn DOF on). I'm getting considerable noise when using that large of an aperture.

Adjusting vertical tilt of VRPhysicalCamera doesn't appear to have an impact on DOF; Streetwise is correct.

Unless anyone else has an idea, I think I'm going to try scaling down the scene (hopefully as an xref?) and treating the scene as a tiny model to get the effect.

EDIT: Oh well, you can't reference a scene with a scale factor. If you use the Rescale World Units under Utilities, looks like it works well for most things, except Forest Pro... will need to figure that out.

[scottwadd]

Streetwise, you're in Bemus Point? No way! I worked at the Lenhart Hotel many years ago.

[Streetwise]

Streetwise, you're in Bemus Point? No way! I worked at the Lenhart Hotel many years ago.

Yepper! Ahh, the Lenhart Hotel... I believe there's probably a rocker with your name on it! How cool is that?

[Streetwise]

Adjusting vertical tilt of VRPhysicalCamera doesn't appear to have an impact on DOF;

I think that's right as you can change the image plane, but not the lens plane (Scheimpflug principle). I still hold a candle for have that ability one day.

[glorybound]

I understand how to use the physical camera depth of field, but how do you override your camera depth of field to make your scene look like a tiny-town without scaling down the scene? Thanks!

it is now built into Photoshop. If you don't mind doing it in post.

[Neilg]

NeilG, I tried enlarging the aperture to achieve that, down to 0.025 for my scene. The camera's focus range planes show up, but they don't seem to have an effect. I'm getting considerable noise when using that large of an aperture.

You're getting noise but there's no depth of field, or you cant set the area thats in focus?

[scottwadd]

Neilg: I'm getting noise but there's no depth of field. Making the aperature that big effects the camera's focus planes in the viewport, but stuff outside of them don't seem to blur. Using a 1.0 aperature, and a small scene, stuff outside the planes is blurred as you'd expect.

Bobby: I tried the lens blur tool with a Z-buffer depth mask. Pretty cool! I like that you can just click different parts of the image and instantly change focus. The tilt-shift feature is nice too, although it doesn't let you use a depth mask that I can see. The issue I have with the depth mask is that it seems to create sharp edges on objects of different depths, when it would be blurred in real life or with vray. Is that a limitation or is there a work around?

[joconnell]

Scott, you tried using a smaller radius of 0.025 and got nothing? You need to go larger on the dof value to get more of an effect.

Sorry, let me qualify that. Try using the depth of field in the render dialog rather than the physical camera one. Rather than using f numbers, this uses something more like a depth of field radius value, larger numbers will make the blur radius wider and you'll get a heavier effect. Try something nuts. The only caveat is that you'll have to use much higher max AA values to smooth out the extra sampling.

[scottwadd]

Okay, I got it! Using the DOF controls in the render settings was the right way to go, as suggested, using very large aperture (5'-0" for my scene), but the thing I was missing is that this only works with a perspective or standard camera--a vray physical cam doesn't work (even when DOF settings are unchecked). Thanks for the help.