How to Composite Video for Inserting Backgrounds in Sets

Sometimes you don’t have a big budget to work with so you need to go by other means to create a set.

In terms of special effects creating your own world with video can add a huge step in a professional direction. Now not all of us can shoot in front of a castle or in the snow or next to a dark, gloomy forest but with some cinemagic we can change our sets in post-production.

The first thing that we’re gonna want to do is find a stock photo that we’d like to use to build our set around. We headed over to iStockphoto and grabbed a picture of a castle that we wanted to use as part of our background. We knew that we needed to shoot some video that matched the trees and environment of our image, so we found a location that had the same trees, harsh road and angled path that the picture did.

Now we took our footage back and headed into our first process with Photoshop. We needed to resize our image to fit into the video frame, then we used the clone stamp tool to add more trees to our location to match it up with our video a little better.

We also used the eraser tool to clear out some of the trees that didn’t seem to mesh with our video and ended up in the way. Once we were satisfied with our image we saved it as a PSD file so that we can drop it into Premier and line it up with our video.

Since we used a PSD file we can still have the subject in the video move freely, completing the effect that we’ve shot in a location that has a castle. To take things a step further we’re going to step into Adobe’s After Effects. This will allow us to create the same effect while utilizing some motion from the camera.

The first thing that you’re gonna wanna do is grab a shot of the subject entering the location that you want to add an extension to, then head over to the layer menu and create what are known as some null objects. A null object is a reference point for the placement of a visual object.

In layman’s terms this basically means that a null object acts as a transparent placeholder. We use multiple nulls to create these transparent placeholders within our clip. The bigger the pan, the more nulls we needed. Once we have connected all of our nulls we used the motion tracking option to match all of our video data within each tracking point.

We do this by first locking in on a given point and doing the same in another frame. After Effects analyzes the data and matches the two together. This also applies to two separate video tracks, or in our case, the image of the castle and the video of our subject. If we do this process just right our video looks as smooth and clean as ever as we watch our subject discover the long, lost castle.

Another step to consider is if you have the subject located in front of the image. In this case since the subject is covering the image it breaks the illusion. A way around this is to make a copy of the areas that appear in front of the image. In this case the subject’s head and arm. Use the mask path option to create a mask along the body parts in each frame that contains a new motion or movement. Since each individual marker can be customized it’s easy to line fit the body parts into each video frame.

The last step is to color correct our video to make the two backgrounds look like one. For some added realism you could add things such as camera shakes and motion in Premier to give off the hint of a new discovery in a new world. Now that’s magic.

Creating video is essentially creating illusion. So now it’s time for all of us to go out there and create some magic.

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