Article #1
Green Screen Work - Creating Alien Landscapes and Holograms

By Kevin Powis

When a young local film maker needed assistance to capture some special effects for a movie he was working on, Lastindependent.com stepped in to provide free resources for the day.

The task was to provide green screen (Chromakey) facilities to enable certain scenes from the movie to be filmed in locations that would normally be unattainable. - In this case the harsh landscapes of a distant alien planet.

Also an interesting special effect was required - to create a hologram of a girl and make it appear in the hand of a menacing hooded character.

Using a carefully lit green screen combined with real time keying provided by a Toshiba laptop we were able to transport the cast to a far away planet. The lap top can key in real time or just be used for live analyse of the shot to ensure it is exposed and lit correctly.

The lighting set-up in this case was dual redheads lighting the green screen. A large Ianiro softbox to provide key light for the talent with dual back lights for 3d separation.

After some careful checking and last minute rehearsals the cast were ready to roll.

Using the latest 3-chip camera linked to the lap-top we captured footage that was suitable for "keying" in of any landscapes or backgrounds.

All the actors had to do was "imagine" themselves in the actual location.

How we achieved the "Hologram Effect"

First we shot the female hologram figure performing her scene. 

In this case, listening to the words of the other character and acknowledging them.

As we needed to merge two green screen images we then provided a solid key colour to the first image.

Next we filmed the other character in the scene performing his lines to an imaginary hologram.

Then again we provided a solid key colour background.

Now, it starts to get interesting!

We then shrunk the female figure to the appropriate size and superimposed the image at the correct position on frame with the hooded figure.

More interestingly we applied a "ripple" effect on the female hologram so she now shimmered and looked like the hologram she was being transformed into.

The final stage is to replace the solid colour with the desired background and the result is a perfect composite video sequence.

The end result shows the hooded man speaking to a hologram floating above his hand. The hologram shimmers and shakes, just like you would imagine a hologram to behave.

Special effects - by Kevin Powis 2005

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