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Old August 1st, 2003, 04:20 AM   #1
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Depth of Field in post?

Hello, I'm new here, this looks as the best forum ever..
Well I was thinking if it's possible (without going crazy) apply a filter in After Effects to give some depth of field to a footage. In the production bundle of AE there is the "depth of field" plugin, but I'm not able to find a tutorial to make it work as expected.
Another way would be applying a mask, but will I have to do frame per frame? Or there is some trick to make the mask follow the subject? Have seen other plugins as IrisFilter4 and Frischluft Depth of field: they works?
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Old August 1st, 2003, 08:11 AM   #2
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dunno 'bout Boris, you can make a mask track the subject by using a mask overlay.
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Old August 1st, 2003, 08:12 AM   #3
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You can keyframe the mask to move over a period of time--do a search on "animated masks" and see where that leads you. Your blurred mask needs to have a feathered edge for it to blend in properly with the clear footage. Obviously, the more movement you have in frame, the more tweaking will be needed. You could load the movie afterwards into Photoshop or Painter and fill in the gaps around your subject with a manual blur tool. I use Synthetik Studio Artist for this because it can interpolate brush strokes...although the result is more of an artistic painterly blur than a classic depth of field look (both have their merits).

The other option is to utilize motion tracking to do it, but I haven't figured that out yet (I'm learning too!).

I wish I could figure out coding, otherwise I'd get into SDK. I've got a couple of ideas for plug-ins that have yet to be made. So much to learn...
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Old August 1st, 2003, 09:18 AM   #4
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masking by hand

This is one cumbersome workflow, but it is possible.
As mentioned, do use a feathered edge.
(On depth-of-field simulation, you can have a larger feather
setting than you would on other effects, such as coloring
separate objects in the frame.)

I basically work like this:

(let's say it's a 1 second piece (for simplicity))

-Move to frame 1, adjust mask, set keys
-Move to frame 30, adjust mask, set keys
-Move to frame 15, adjust mask, set keys
-move to frame 7, adjust mask, set keys
-move to frame 22, adjust mask, set keys
-move to frame 4, adjust mask, set keys
- etc, etc

The patern there is to work in 'halves'.

The reason you want to do this and not do it linearly is to
establish a general motion of the mask, as opposed to starting
at frame 1 and moving ahead one frame at a time, which will
give you a lot of jitter if the mask moves too much over a one
frame interval. (With feathering, this jitter is greatly reduced.)

However, you don't want to allow the software to do all the
inbetweening for you, because your mask will slide linearly
from point A to point B, whereas the motion in the footage,
because of its organic nature, and (in some cases) motion
of the camera, is definately not linear.

So, establish the broad, general tracking keyframes, THEN go in
and set a lot of inbetween keyframes.

Hope this helps!

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Old August 1st, 2003, 05:08 PM   #5
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Good tip Frank...I use a similar approach in Studio Artist for keyframed brushstrokes (halving)...forgot to mention that specific for working in AE.
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Old August 1st, 2003, 07:09 PM   #6
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the biggest problem that I find with post-DOF is that even with careful masking (in Combustion I track the object, apply this data to the mask so it follows accurately the basic movement, then adjust the points to rotospline precisely) is that you don't really get "depth" of field. That is; in a real image with shallow DOF the defocused area of the image varies from in focus to slightly defocused to out of focus. With the masking effect your subject remains in focus and the background out of focus - but there is no blending in between the foreground and background. While it works for alot of shots (medium close ups and the like) on a slightly wider shot it's a dead giveaway.

Of course you can split your image into three duplicate layers, mask each one separately and apply defocusing (and make sure it's a "defocusing" effect and not just a blur - they are two different things), to get the variation - but my god, it's a lot of work. I did this in alot of shots on a short film i made a few years ago, (basically a misguided attempt to rectify my bad cinematography). The final result was pretty good but man, it was WEEKS of work.

I'm waiting for one of these bright sparks to come up with a plugin that allows you to quickly select areas of an image and click the "DOF" button. Yeah... now ya talkin'.



P.S. not 100% sure but I think the DOF plugin in AFX is a 'Z-depth' plugin - for simulating DOF on CGI images rendered as rpf or rlf files - i.e. they have Z-depth information in the image file to tell how close or far away the object in the scene is from the camera. The plugin then uses this information to apply DOF. Therefore it won't work on normal 2D images or video.
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Old August 1st, 2003, 08:17 PM   #7
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David: Absolutely right! To make the DOF simulate how it REALLY
looks, each object in the frame has varying amounts of blur.

Doing post DOF in 3D animation is easy, because you can render out greyscale z-buffer information and apply varying amounts of blur based on that.

(Come to think of it, 3D has a lot of advantages: 24p (or any framerate), and any lens adapter imaginable from fisheye to extreme telephoto.)

Another thing is that just using gaussian blur in After Effects (although it does generate a passable effect), isn't exactly what happens in real life, either.

However, you'll notice that a lot of commercials and things are using a flat blur on the sides of the frame, or at the top or bottom. Seems to be a popular thing to do nowadays. I guess they are doing it for looks, or to lead the eye maybe. Not sure.

I am interested in Bokeh simulation, but there aren't a lot of affordable applications that support this effect. This can be acheived somewhat by using the maximum (or minimum?) filter in After Effects, combined with some gaussian blur.
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Old August 1st, 2003, 09:50 PM   #8
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post DOF effects are a headache waiting to happen

There are many horror stories from the trenches of major motion picture effects houses of having to rotoscope, frame by frame, a foreground element in order to isolate and modify the frame.

If you want absolute control over DOF, and don't have the camera to do it, consider greenscreening each layer of your elements and compositing them. Of course, green screen and compositing is whole 'nother level of commitment. :)

Otherwise, try to compose DOF in-camera.

Michael Morlan . cinematographer | local 600 operator .
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Old August 22nd, 2003, 08:23 AM   #9
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Creating multiple masks may not be as hard as you think. I've only done this with Adobe Premeiere, but the process should work in any editor that uses multiple video tracks. This is actually a variation of a technique I use for green screen work (there is another thread on this, do a search for Greenscreen settings)

I'm not familiar with other editors, so I will use Premiere to illustrate. To create a mask for a particular layer, import your footage into your editor and put it on track 2. In transparency settings, choose Chroma from the drop-down. Use the eye-dropper to sample the color of the portion of the image you want to make transparent. Click on th Mask Only check box, and voila! you have a mask. Use the settings in the dialog to adjust the mask to taste.

You will probably have to clean up this mask, so create a title and apply white and/or black shapes to your title to cover up problem areas. Once this is done, render the clip. Do this process for each layer to which you want to change the DOF (Hint: Dont worry about the very bottem layer, i.e. the area farthest away)

Import these clips into your project. Place the original footage on track 1a. Apply your blur filter of choice, adjust to taste. Place the mask clip of the next farthest away part of the clip on track 2, apply a slight blur, and in transparentcy setting change to Traveling Matte. Place the original clip onto track 3, apply blur filter to taste, change transparency to Traveling matte, etc. You can apply multiple layers this way, just remember that the mask goes first, then the original clip, and all overlay tracks need to be set to Traveling Matte. The biggest problem you will have is render time. A typical greengreen render for me is 4 layers, and I only get about .3 frames per second (on a Duron 900--wife won't let me dump huge amounts of money on both video gear AND computers<grin>). Blur effects will add more time to the renders.

Experiment around and let me know what you think.

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Old September 27th, 2003, 02:00 PM   #10
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IrisFilter4 for AfterEffects is just released!!
The Virtual Lens with true representation of depth-of-field that gives the natural taste of camera lens to your 3D images and genuine perspective to your video composition.
(This is a plug-in software for Adobe Photoshop and Aftereffects.)
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Old September 27th, 2003, 09:37 PM   #11
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That plug-in is for 3-D CGI, not video...
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