5D.Snow

PURPOSE
Simulates falling snow using particle systems. Snow is created along a line in the image chosen by the user. This line can degenerate into a point. The area in which snow is generated can be controlled simply by picking up icons in a graphic overlay presented over the image display. Snow can be made to settle on features described in a second clip.

INPUT CLIPS
Background Clip: the clip over which falling snow is to appear.
Settle Clip: the clip containing black and non-black areas. This can be used optionally to cause snow to settle on the non-black parts of this image.

Tips:

Snow is a time based effect; the characteristics a particle is born with, will evolve over time (every frame generated) to create the effect. Jumping to a random frame will not show you the same result as when the sequence is generated sequentially.

Each particle is created with certain birth characteristics. On the frame they are born they are given:

lifetime
fadeout factor
an initial velocity and variance
a birth position ( the birth generation line )
a color (RGB) with variations (Color variance & Mono variance)

These factors are only changed by other forces acting on them.

animating the color will not change all the particles, only the particles that are born at that frame; but the color may fade over time.

the initial velocity causes the particles to move, but then gravity, wind; swirling, friction etc take effect.

Settling Snow: Snow can be accumulated in areas controlled by the Settle Clip. The intensity level must be 128 or greater for the snow to settle. Snow will gradually build up, snow settling on snow.

TIME EDITOR CONTROLS

CREATION
Preroll Frames (Min: 1 Max: 1000 Default: 50)
How many frames to run the particle system before generating the first frame of the output clip if Do Preroll is selected.

Density (Min: 0.0 Max: 10000.0 Default: 1800.0)
Average number of snow flakes created per frame.

Lifetimeion (Min: 1.0 Max: 1000.0 Default 200.0)
Average lifetime in frames of a snowflake. When they reach the end of their lifetime they pop off ( have very quickly melted ).

POSITION
Radius (Min: 0.0 Max: 500.0 Default: 2.8)
Distance from the snow generation line within which snowflakes may be created.

XY Left (Default: top left)
XY Right (Default: top right)
The ends of of a line along which snow will be created.

SIZE
Flake (Min: 0.0 Max: 20.0 Default: 4.0)
The maximum size a flake can be.

Flake Variance (Min: 0.0 Max: 100.0 Default: 100.0)
The posibiltiy of flakes of different being created.

FORCES

FALL
Rate (Min: -100.0 Max: 100.0 Default: 10.0)
The initial speed given to a snow flake when created. The direction is always in the direction of gravity.

Rate Variance (Min: -100.0 Max: 100.0 Default: 100.0)
Size of random variations in initial speed of a snow flake. The direction is always in the direction of gravity.

GRAVITY
Strength (Min: 0.0 Max: 1000.0 Default: 0.1)
Scales the strength of the gravitational force.

Angle (Min : 0.0 Max: 360.0 Default: 270.0)
Controls the angle at which gravity acts, measured in degrees clockwise from due East. The default is towards the bottom of the image.

SWIRL
Density (Min: 0.0 Max: 100.0 Default: 28.8)
Number of turbulent bumps in the atmosphere across the frame. The smoke can bump into these, causing them to swirl.

Amplitude (Min: 0.0 Max: 100.0 Default: 0.0)
Strength of the turbulent bumps in the atmosphere.

To Maximum (Min: 0.0 Max: 500.0 Default: 0.0)
The swirling of the atmosphere builds up from zero to its specified amplitude over this number of frames.

Friction (Min: 0.0 Max: 100.0 Default: 1.0)
Controls the frictional force of the atmosphere on the drops as a percentage of the drops velocity lost per frame. Slows the smoke down and helps it swirl more densely.

SNOW COLOUR
Red/Green/Blue (Default: light greyish blue)
The color given to the snow flakes when they are created.

Color Variance (Min: 0.0 Max: 100.0 Default: 0.0)
Random variation in the color of the smoke particles.

Monochrome Variance (Min: 0.0 Max: 100.0 Default: 0.0)
Random variation in the brightness/density of the snow flakes.

SETTLING
Chance (Min: 0.0 Max: 100.0 Default: 5.0)
Set the probability that a flake of snow will settle when it encounters non-black in the settle clip.

PI CONTROLS

restart
Restart the snow storm, destroying all current snowflakes first.

preroll
Run the particle system for the specified number of pre-roll frames before generating the first frame of the output clip.

RENDER PREROLL
This MUST be turned ON prior to rendering a sequence if you need the preroll effect. Rendering starts a completely new snow storm; it cannot continue from where you currently are.

CLIP CONTROL
settle (Default: Off)
Off: the snow ignors the settle clip and continues to fall.
On: if a flake encounters a non black region in the settle clip then, depending on the Chance setting, the flake may stop there, settle.

RENDERING
colour & density/colour/density (Default: colour & density)
These options affects how the raindrops composite with one another and with the background image and may have a great effect on the final appearance. For rain, using Density is usually best.

DEMOS
base and fine and heavy
Set all snow parameters for different styles snow storms.

5D.Snow

Index