Comments

John_Cline wrote on 1/22/2012, 4:58 AM
Is the background a solid color, either green or blue?

If not, did you shoot this on a tripod and do you have a shot of the full background without the person in it?
Mokondzi wrote on 1/22/2012, 5:49 AM
The background is buildings since I shoot it on a balcony; I shoot the video using a tripod. I do not currently have the shoot of a full background without the person but I can get it immediately.
Chienworks wrote on 1/22/2012, 7:24 AM
That could be problematic as the shot has to be exactly the same as what's in your existing video. If the lighting is at all different then it probably won't work.
John_Cline wrote on 1/22/2012, 4:34 PM
Vegas is a capable piece of software, but not that capable. What you want to do is practically impossible.
Tech Diver wrote on 1/22/2012, 5:52 PM
It can be done if you are willing to put in a lot of work. Namely, go into Pan/Crop to manually create an animated mask with LOTS of keyframes. If you would have had a shot of the scene with no person you could have done difference masking: http://www.sundancemediagroup.com/articles/dayvids/difference_masking_in_sony_vegas.htm

Peter
John_Cline wrote on 1/22/2012, 6:13 PM
That's why I said "practically impossible" and not "absolutely impossible." Like you said, creating an animated mask is incredibly time consuming and likely not practical. Chroma Key and difference masking both require very controlled conditions and shooting outside on a balcony with uncontrolled lighting conditions simply won't work.
musicvid10 wrote on 1/22/2012, 9:56 PM
Absolutely possible -- if you plan to spend the next ten years of your life to fix a couple of minutes of video . . .
;?)
Steve Mann wrote on 1/23/2012, 2:04 PM
You could export the clip as a sequence of JPEG images and use Photoshop to make a mask for each frame then re-import the masks sequence into Vegas. A little faster, probably, than tedious keyframing and bezier masks. Topaz Labs sells a Photoshop plug in called "Re Mask" that works pretty fast.
johnmeyer wrote on 1/23/2012, 4:26 PM
Actually this can be done, although there are a few caveats.

First, the thing you are trying to do is similar to what is done with a green screen or blue screen. As I'm sure you know, that operation is called a "chroma key" and involves replacing every occurrence of a particular color with video from some other source.

It turns out that the same thing can be done if, instead of being a solid color, the background is an unchanging static shot. That static background can be subtracted out from the live shot and then replaced with something else. This operation is referred to, at least in the Vegas world, as a "difference mask" or "difference key" or "difference matte" or "difference compositing." You can search this forum for all sorts of discussions about this. I happen to have links to a few of these in my Vegas database:

Help with difference key technique

Key difference technique-Look at the results!

Difference Key Tutorial

You should also search for "Two cats" which will lead you to this very old, but still relevant, demo by one of the Sony Vegas engineers:

Cat Demo

Whether you can do this with your current situation, I don't know. You might be able to generate a still shot of the background by taking frames from several parts of the video and, as your subject moves around, you will get various parts of the background that are obscured by the foreground in other frames.

For this to work, you need to have an unchanging background; the camera MUST be on a tripod; and the lighting on the background should not change too much.

Here's a link to something I did many years ago where someone asked me to composite him into the "American Idol" set. I've posted this before. He sent me footage taken in front of a wall in his house, and he just started the camera, walked into the scene and did his shtick. I used a still photo of the American Idol set as the background.

Difference Matte Example

I did this for an old friend who wanted to surprise his new wife on her birthday. This was shown at a private party and, other than these private postings here, was not used in any other way.

Here's the VEG file I used for this example:

Difference Key Example