Hey guys, welcome back to the channel.
Today's video comes from the recent Doctor Who Christmas special which aired at the end
of last year- I'm going to be showing you how to add frozen snow into your shot, complete
with realistic 3D motion.
This effect requires HitFilm Pro, since we'll be using the particle simulator.
But if you don't have Pro we've got our January sale going on right now, which is 15% off
the entire store.
Let's jump into the software and get started.
Here I've got my footage in its own composite shot.
To begin tracking in Mocha, drag the mocha HitFilm effect directly onto the layer.
In the Controls panel, drop down the settings and click this button to Launch the mocha
UI.
I'll come up and select the X spline layer tool and draw a shape around this formation
of rocks.
Rename all of your shapes so that you can keep track of them.
Down in the Motion category I'll checkmark Perspective, since our shape appears to be
transforming in 3D space throughout the clip.
Let's turn on the Surface and Planar Grid, and align the blue square so that the grid
matches the angle of the snow.
You generally want to keep the tracked surface, which was the red spline we drew earlier,
as large as possible.
But the surface, this blue square, should remain small.
Hit Track Forward to begin.
Once that track is complete, come up here and turn off processing so that Mocha doesn't
try to track it again later.
You can also lock the layer if you wish.
We've now got an element in the foreground tracked.
Now we need something in the background to be tracked so that mocha can accurately create
a 3D camera.
The mountains here are far enough away that they appear as a single flat plane, so we'll
track those.
However, the man on the rock is standing right in front of them.
We can tell mocha to ignore him when we track the mountains, but that means we have to actually
track his movement as well.
Again, select the X spline tool and draw your shape.
It doesn't have to be an exact shape at all, just a rough outline will do.
Up here in the Layer panel, drag this shape under the first foreground rock layer.
This tells mocha that he is behind the rocks in camera, even if it's just by a few feet.
I won't set the surface or grid for this layer, instead I'll just track forward.
If you need to reposition any of the points during the track, feel free to do so.
Mocha will add a keyframe to change the shape.
Once again I'll lock this layer and turn off processing.
The final track will be the mountains in the background.
Draw your shape, or shapes, if that results in a better track and rename the layers.
I'll place it below all of the other layers, since it is far back in the scene.
Because it's below the shape of the man, mocha will ignore him in the track, since it knows
that he is in front.
Once that's done, I'll turn back on all of the layers and highlight them.
Come down to the Camera Solve tab and in this case select Large Parallax Change, since that's
what's happening in the scene.
Then click Solve.
Choose Export Camera Data and save the file to your computer.
Back in HitFilm, choose Import Composite Shot and find the file you just saved.
Delete the Plane and drag in your video.
You should see the movement aligned.
Drag the Particle Simulator into the timeline.
Under General, set the Time Shift to -1 second.
In the Emitter settings, change the shape to Cube, and increase the size to cover the
whole scene.
Search for Speed and set that to 0 to prevent the particles from moving.
To stop them from continuously appearing, activate keyframes for the Particles Per Second.
Skip one frame forward, and set it to 0.
Raise the Life to 60.
Now of course, the snowflakes should not all be the exact same texture.
I have 4 PNG pictures here that I want to use, so let's set that up.
Create a new Composite Shot that is 4 frames long, or however many pictures you have.
Import your images if they aren't already and drag them into the timeline.
Shorten them to one frame each.
Back in the main comp, add in that snowflake composite shot and hide it from view.
In the Appearance section for the particles, change the Texture Source to Layer and then
choose the Snowflake Texture comp.
They're not different yet- change the Frame property to Random.
What HitFilm is doing is picking a single frame from the Snowflake composite shot to
use as the texture for each particle.
Since there are only 4 frames, there are only 4 options, and since each image only lasts
for a single frame, they all have an equal chance of being chosen.
Uncheck Billboard so that the snowflakes don't have to be facing the camera the whole time.
In the Movement Variation category, set the Rotation X, Y, and Z to 1 times over.
This means that the particles can face in any direction, from 0 to 360 degrees on each
axis.
Adjust the scales of the snowflakes to your liking- I'll keep them a bit larger than normal
so that you can see them in this tutorial.
Now we have a slight problem in that the particles that should be far away are appearing in front
of my foreground subject here.
Since the geometry of the subject is simple, we're going to use Deflectors to mask out
the snowflakes.
In the Controls for the particle simulator, click this plus icon next to Deflectors.
I'll name this one "body" and you can see that it's a cube shape.
But it's in the wrong position, if I play it through it'll eventually move offscreen.
Adjust the Position in the Shape properties, or copy and paste the data from a nearby tracking
point.
Now increase the Width, Height, and Depth to cover his shape.
Change the rotation of each axis to make it fit better.
It's not having any effect yet, all you have to do is checkmark this Mask box to turn it
on.
Because this Deflector is positioned in 3D space, it will now occlude the snowflakes
that are behind it, but not those in front.
I ended up having several Deflectors in my scene, for the backpack itself and the rock
and mountain below, but you might not even need these, depending on your footage.
I added a couple of effects to blend in the snowflakes better.
First up was a very slight blur, then some Noise to match the scene.
The Light Streaks effect adds colored rays onto each particle, and is great for adding
style to the particles.
Lower the Threshold to make all of the snowflakes affected, or raise it to have only a few.
Adjust the Size to your liking, then set the Blend to Add or Screen.
Don't forget to turn on motion blur for the particle layer.
Thanks for watching guys!
If you've ever recreated an effect from Doctor Who, feel free to share it down below.
Let me know if you have any questions and I will see you all in the next video.