In my last YouTube tutorial I showed you how to create the aggressive horror zombie speed run effect from our Zombie Hunter VFX short film.

Here is the promised detailed blog tutorial of how I created this zombie effect in Adobe After Effects :)

The Final Effect

As you can see from this frame from our zombie hunter short film, the effect adds a dark, super human speed effect to the zombie.
This helps portrait the zombie WAY more dangerous than your average zombie-shuffle variety :D

Preparing the Footage

We filmed Celina from Fables In Fashion playing the zombie, getting up and racing from side to side through the scene while I slowly follow her movement with my gun, pretending to not be able to keep up with her speed.

We should actually have filmed the scene twice!

• Once just with Celina in the scene
• Once just with me in the scene

While it seemed like a good idea at the time, simply speeding up the clip made my movement seem jerky and unnatural. And I wanted my movement to seem natural so that the incredible speed of the zombie seemed super human by contrast.

So I spent a bit of time cleaning up the shot and removing myself from the scene using a clean plate (an image of the scene without anyone in the shot) and some masking :)

Let’s tweak the timing of the footage to give the zombie some more speed!

Time Remapping to speed up the Zombie

The next thing I did was time remap the zombie layer inside After Effects. I wanted the zombie to move really twitchy and fast. You can enable time remapping simply by selecting the layer and going to Layer -> Time -> Enable Time Remapping. You can then create and drag around keyframes and compress or expand certain time durations on the clip :)

I created keyframes around the turning movement of the zombie as well as for the 3 running sections of the shot and compressed the space between them to speed those sections up.

This resulted in the zombie turning around in a flash and racing with super human speed from side to side. At each side I let the speed return back to normal so that the running seems even faster by contrast and it doesn’t just look like the entire clip is sped up :)

Enabling CC Force Motion Blur

Since I want the zombie to appear to have super human speed, I added additional motion blur into the scene by applying the CC Force Motion Blur effect to the layer.

By setting the Shutter Angle to 300 degrees I increased the motion blur on Celina as she is rushing from side to side.

Creating Shadow Trails with the Difference Matte Effect

Next, I wanted dark shape shadows to follow Celina as she is racing from side to side to emphasise the speed of the movement and add a ghostly horror effect :)
For this, I added the clean plate photo into the composition.

Because I only used this layer as input to the Difference Matte effect, we can disable the visibility on it.

Next, I duplicated the time remapped layer of the zombie run and applied the Difference Matte to it. You can find this effect by searching in the Effects & Presets panel in After Effects.
Next, in the settings for the effect, I selected my clean plate as the ‘Difference Layer’ and set the View to ‘Matte Only’.

The Difference Matte effect will detect differences in pixels between the layer it is applied to and the difference layer provided. So compared to our clean plate, we have the Celina zombie in the shot. With the ‘matte only’ option selected, we will then get a rugged black and white image of Celina’s shape.

I also increased the matching tolerance and matching softness of the Difference Matte effect to 13 and 31% respectively to shoothen out the matte so the shape looks more like a ghostly shadow.

Because I want a dark shadow so I can multiply the layer over my footage, I applied the Invert effect to my zombie layer :)

This gives me a black shadow where Celina’s body is. Note that there are some unclean artefacts in the image that we can remove with masks :)

I then set my shadow trail layer to multiply and shifted it by a single frame to the right (= delayed it by one frame). This causes a dark shadow to trail directly behind Celina as she dashes from side to side.

Repeating this process a few more times and delaying each new shadow trail layer by an additional frame adds a nice smooth, ghostly trail to the zombie :)

Here is the shot with 3 shadow trails on top of the zombie speed run base footage!
Note that the clean plate visibility is turned off because it is only used as input to the Difference Matte effect :)

Since I only want the trail to be visible while the zombie is running, I animated the opacity on all the shadow trail layers to fade in only during the zombie run and fade out when the zombie stopped :)

Finally, let’s add some cool particles to complete our zombie run effect!

Zombie Particles

Lastly, one thing I like to do with almost all my effects, I added some particles to make the final VFX look a bit fuller :)

In our Zombie Hunter VFX short film I actually used the Particular plug-in by Red Giant, but you don’t really need it to create some nice dark floating particles and here is how you can achieve the same effect with the inbuilt CC Particle World effect!

I created a new solid and applied the CC Particle World effect to it.
You can disale the horizon and the grid on the effect as we don’t need to see those helpers.

Next, I animated the position of the producer to follow the zombie’s movement across the scene. I also animated the birth rate to only emit particles while the zombie was running since I want them to be an effect of the super fast movement.

In the producer options I then changed the shape of the producer to a thin vertical line about the height of Celina so the particles seem to be emitted from her body as she runs :)

Next, I set a few parameters to get nice and dark floating particles

1. I set the particle to be a Faded Sphere
2. I set the Birth Colour and the Death Colour to black
3. I set the Birth Size to about 0.15 and the Death Size to 0
4. I set the Velocity to 0
5. I set Inherit Velocity to around 10 (this will fling them in the direction the producer is moving)
6. I set the Gravity to -0.1. This will make them slowly drift upwards

Now dark particles that drift up slowly and disappear are emitted behind our speed zombie and with that the final effect is completed :)

I hope you enjoyed this tutorial! More cool VFX tutorials coming soon :)