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[ Lectures and Technical Notes ]
After Effects Tutorial

Using the Green Screen:

1. Move your objects away from the green screen to avoid green color spill

2. Make sure there is no green in your animation objects (be careful about colors close to green)

3. White might pick up the green colors

4. Reflective objects might pick up the green also

5. You MUST have the camera in focus to avoid blurr because this will be hard to remove the green

6. Avoid shadows and light variation on the green screen

Lights (Key light, fill light and back light):


Color keying

Effect menu - Keying - Color Key



Key Color - Use the color picker to select the color you want to get rid of

Color Tolerance - will allow variations of the color you chose to be affected

Edge Thin - The edges of where the color is will be affected

Edge Feather - Around the edge it will become blurry (anti-aliased)


Luma Matte

We are using sand animation as an example.



The source footage should have good contrast and with white or black background.

Use the same source footage to create two video layers. I will call the top layer as Matte layer, and the bottom layer as Source layer

Add another image/ video as the background layer at the bottom.

 In timeline: it should look like this:


* Turn off visibility for the matte layer

Set the source layer TrkMat as Luma Inverted Matte "matte layer"

It will look like this:

Color adjust the matte layer to get a better quality matte, e.g. Levels, Hue/Saturation, Curves, etc.

To add effects to the matted layer, you need to make a pre-comp before any extra effects to be applied:

Select both matte layer and source layer, Layer menu > Pre-compose



 A pre-composed animation with an effect:



Blend modes (you need more than one layer for this to work)

Expand the transfer Controls Panel


Select the top layer and apply a Mode by pulling down on the Mode menu

OR

Layer menu - Blending Mode - pick one


Fade in and Out

Select the clip and open the Opacity by hitting the t key

Position the time slider where you want the fade to start

Set a key by clicking the StopWatch

Fade In: the first opacity key should be 0%

Go to where you want the fade in to end and set the Opacity to 100%

Fade Out: the first key should be100%

Go to where you want the fade out to end and set the Opacity to 0%


Cross Dissolves (need two different clips)

Each clip will be on a different layer

Overlap a portion of the clips

The length of the overlap should be the length of time you want the cross dissolve

At the start of the overlap - Set a key on the Opacity (t) for the top layer - set it to 100%

At the end of the overlap - Set a key on the Opacity on the top layer - set it to 0%

Ram Preview and adjust the overlap and keys till the timing feels right.



Adjusting the speed of clips

Layer menu - Time - Time Stretch...

100 % = original speed

50% = half as fast as original

200% = twice as fast as original



Audio Tools

Import an audio file (wav works best - AVOID using mp4)

Open the triangle next to the audio layer

Open the triangle next to Audio

To adjust volume:

Click the Stopwatch to set a key on Audio Levels

Adjust the dB

Positive number + will make it louder

Negative number - will make it quieter

Set it to -48 dB to make it silent

To sync sound to the visuals:

Open the triangle next to Waveform (or select the clip and hit the lowercase L twice fast)

Use the mountains to see the waveform better

To play the sound and animation: (space bar won't work)

You can set the workspace by moving the handles on the top of the timeline

Do a RAM preview

To play the sound alone:

Set the playback head to where you want the audio to start

Hit the Control . (period) key

or

Composition menu - Preview - Audio Preview (here forward)

To SCRUB through the audio:

Hold down the Command key and drag the playback head along the timeline track