Video Compositing: Steam

Video compositing refers to merging 2 different video shots together. These composites will overlay 1 video shot that was shot in front of a blue screen or green screen and other footage. Video compositing allows for individuals to be placed in different environments and even virtual sets. In particular, steam can be achieved. Steam is high temperature and can be dangerous not only to actors, but also any set that is nearby. Unlike a lot of other effects, it is not necessary to spend a lot of money to get excellent results.

Step 1: Background

The background that will be replaced needs to be set up properly. The best green screens are those that utilize green screen paint, as this will contain only 1 shade of green. Therefore, when compositing, only 1 chroma key will be replaced. A piece of green fabric will contain many different shades of green, which makes compositing more difficult.

Step 2: The Footage 

Shoot the 2 different footages that will be composited. How the steam is to be used will determine whether to shoot it on green screen or not. If the steam is only in a small portion of the shot, then shoot the steam in front of a green screen and then the rest of the scene as normal. Because steam can be changed and expanded, only a small green screen background is needed behind the steam.

Step 3: Software

Video editing software is needed to composite steam. There are many different software packages available. Some software will only composite green screen effects, while larger packages will contain green screen effect functions and many other video editing functions. If you plan on doing a lot of video editing, then investing in some good software will make the entire job very easy. 

Step 4: Chroma Key

To composite steam, the green screen background will need to be removed. This is known as chroma key. Cut out the green screen and then replace this background with a new layer that contains the additional footage.

Step 5: Steam without Green Screen

Steam can also be added without doing green screen replacement. Different layers will need to be used within the video clip. Create a new layer to add the steam effect. Make the foreground color be white, and make sure that the brush opacity is low. Brush vertical lines where the steam should be placed in the starting of the video where steam is needed.

Step 6: Smudging

The white lines do not look like steam. Use the smudge tool with a 50% opacity to distort the lines. Massage them to look like steam that is wafting around. As the video moves on, create new layers to show the steam moving and changing. To create a 3D effect, several layers of steam are needed. Creating steam this way is much more labor intensive, as the steam needs to change throughout the video clip. 

Step 7: Finishing Touches

With green screen, compositing is necessary to blend the steam into the new picture. Simply use a smudge or blending tool to ensure the steam seamlessly blends into the new footage. The final finishing touches are what create a realistic composite, rather than one that looks like it has been composited.