Depth of Field w/Multipass?

[largento]

Okay, I'm wandering into new territory again and need some help. :-)

 

I'm working on a shot for the Christmas greeting I'm doing and I want to do a focus switch ...to transition from one character to another. So, I've turned on Depth of Field in the camera and set it up. When I do a preview render with no multipass, I get exactly what I would like. Foreground character is in focus, and background character and set are nicely out of focus.

 

 

But when I do a multipass render, not so good...

 

 

With more passes (say 9), there's almost no blurring at all.

 

Is there a trick to this?

[photoman]

I believe I heard some say that a 16pass (4x4) render is equal in DOF and motion blur. But... I could have misheard.

 

Photoman

[Rodney]

I'm working on a shot for the Christmas greeting I'm doing and I want to do a focus switch ...to transition from one character to another. So, I've turned on Depth of Field in the camera and set it up. When I do a preview render with no multipass, I get exactly what I would like. Foreground character is in focus, and background character and set are nicely out of focus.

 

It reads to me as if your setting at Tools/Options on the Render Panel isn't set to render using the active Camera. Alternately, you could set the DOF in the render options there but... I recommend using the camera.

 

This may not be what you are experiencing but it might be worth looking into.

 

Edit: Doh! I should have looked at your images. It does appear that DOF is working. Photoman may be right. I think its just a matter of finding the right Multipass settings (Don't forget you can adjust the Blur)

[largento]

I believe I heard some say that a 16pass (4x4) render is equal in DOF and motion blur. But... I could have misheard.

 

Photoman

 

Thanks, Photoman.

 

16 passes does seem to render the focus a little softer, but I'm still not getting the dramatic out of focus that no multipass is giving me.

 

Rodney, maybe that's what I'm after. How do you adjust the blur?

[HomeSlice]

Are you sure you need multipass? Are you rendering with AO, SSS or any of the other things that require multipass?

Have you tried a short render test with multipass turned off to see if you really need multipass?

 

I've played a bit with DOF, but my results have been kind of inconsistent, so I'm assuming there is something that just isn't "gelling" for me yet. Anyway, there are two places where you can adjust the blur: In Options -> Rendering -> Depth of Field, and in the camera properties. I would suggest, like Rodney also suggested, to try adjusting the settings in the camera properties. Make sure "Use Settings From" is set to "Camera" in the Options -> Rendering panel. Then go to your camera properties, under "Render Options -> Depth of Field" (Make sure the quality setting is set to "Final") and there you can change the values for Focus Distance, Near Focus and Far Focus.

[Rodney]

Also (just in case) Depth of Field is usually best adjusted from a Top View in the Choreography.

Sometimes you think you may have the settings right until you see otherwise in the top view.

(Temporarily hide any large objects that block your view)

[largento]

I'll see how it goes with doing it single pass. If the quality doesn't match up, I'll render the scene out twice with the foreground and background separated and animate the blur in AE.

[frosteternal]

Single pass (A-buffer) fakes the depth of field. The result is very pronounced, but not necessarily "correct".

The multi-pass focal blur is more accurate, and will be as obvious as you make it. For dramatic rack-focus shots, use very shallow depth-of-field. The in-focus area should be extremely narrow. (The camera cone has adjusting handles so you can adjust this easily and intuitively.)

To get "quality" DOF, you may need up to 64 passes. It really depends on the shot. For some shots, you may want to do the blur in comp.

But subtle, more accurate DOF can be invaluable in "selling" a shot as real.

[robcat2075]

You got my curiosity going so I did a simple test

 

In this animation, it starts at 0:00 with the near and far focus enclosing the just the depth of the closest box.

 

from 0:00 - 1:00 the far focus moves back to include the distant box.

 

from 1:00 - 2:00 the main focus distance moves from the closest box to the distant box.

 

from 2:00 - 3:00 the near focus leaves the close box and moves back to just in front of the distant box.

 

first with no multi-pass

 

dofNormal000.mov

 

 

now with 25 multi-pass

 

dofMP000.mov

 

 

I think either of these are usable in certain situations, but for the most control I think you'd want to render a depth map and do your DOF blurring in a compositing app.

 

 

 

 

I believe I heard some say that a 16pass (4x4) render is equal in DOF and motion blur. But... I could have misheard.

16 pass is equivalent in anti-aliasing of a regular render.

 

DOF and motion blur are quite different issues.

[largento]

It's a fairly short shot (less than 3 seconds), so either way of faking it should work for me. I'm using it as a story-telling device, not as a means to capture any perceived reality. :-)

 

Thanks for the input, guys!