Audra Coulombe is the Marketing Manager for The Molecule, a VFX, Motion Graphics, and VR company located in New York and Los Angeles.
For those of us in frigid climes, it might just be early enough in the winter that snowfall can still be charming. Some of us might even hope for snow, as TV shows and commercials with their snowy scenes would have us believe that the holidays without snow just wouldn’t quite feel like the holidays. If it doesn’t snow on your holiday, though, don’t be dismayed. It probably didn’t even really snow in the wintry scene you see on TV! It’s far more likely that the snow was generated by a team of artists who have become so well-practiced at observing nature that they were able to recreate it themselves.
Watching the TV sitcoms of my youth, I remember noticing how fake snow could seem. Pieces of white, cut-paper-like stuff blowing in from a fan slightly off-screen were easy to spot, even for a little kid. But for many production teams, waiting until the next big blizzard to shoot their scene isn’t always smart, practical, or safe, so over the years they have turned to VFX teams to make it snow. At The Molecule, snow is a very common effect that we create, so we tend to use one of two methods when setting a snowstorm into motion.
Creating 2D Snow
Next time you’re in a snowstorm, take time to really look at how the snow moves. Snow near your face looks bigger and will appear to be falling quickly. Snow far away has smaller flakes and looks like it’s falling at a slower velocity.
Of course, this is an optical illusion created by perspective — all the snow is more or less falling at the same speed and at the same size in your immediate vicinity. But in order to replicate snow onscreen, a VFX team has to think about how a human being really sees it.
Snow created in 2D is essentially a huge stack of transparent snow layers, each moving at a different speed with flakes of different sizes.
(From Elementary on CBS)
This method works especially well for creating blizzard-like conditions. You can have a large variety of plates with various sizes and speeds, and it’s easy enough to integrate your actors in between the layers in post.
This isn’t a great solution if your camera is moving a lot. Like all footage, your snow footage has edges to it and a finite duration. If your camera moves, your snow plate can only move so far. Instead, you’ll have to stitch together multiple pieces of the same kind of snow, which can sometimes be a little tricky. Also, if your main footage is longer in time than the length of your snow footage, you’ll have to loop your snow footage, which can run the risk of looking fake. For this reason, there’s a second method of creating snow that we like to use for these situations.
Creating 3D Snow
3D snow is an awesome solution for many reasons. You can generate it to be any length, and it doesn’t have any definitive edges. It also works well if you’re not finding the 2D snow footage that you’re looking for, because you can generate whatever kind of snow you want, from a light flurry to a complete whiteout. It’s also perfect if you have a shot that’s moving in slow motion.
We use Maya and Houdini in-house to generate our 3D snow, and they allow us to create incredibly detailed, specific, high-quality snow. Keep in mind, though, that 3D snow is usually a much more time-intensive and expensive solution.
Things to Remember
Match the snow’s focus to the closest object. If you have a wide shot of two people walking down the street, for example, you’ll want the snow that is furthest away to match the focus of the tree it’s falling near. The same principle applies to both 2D and 3D; however, you’ll need to set the focus manually for each layer in 2D, whereas 3D snow can tell your compositing software what the focus should be at any given spot.
Snow can look different to different people. For example, our compositing supervisor Rick Shick insists that when watching real snow, “there’s always a certain layer that seems to be moving up.” A blizzard to someone in Alaska will also look different than to someone in New York. Working with clients might be a good occasion to use 3D snow so that you can get the specific look he or she is asking for.
You can get “snow-blindness” in post. You know that feeling when you’re driving in the snow, and it looks like you’re driving through a snow tunnel and it’s easy to be completely mesmerized? This is totally true in VFX. CG supervisor Manuel Riedl says, “It’s easy to focus too hard and lose your mind.” It’s great to take occasional breaks and rest your eyes with this particular effect.
Don’t completely ditch practical snow on set. Practical snow does have it’s uses! It’s important for the actors to be able to interact with it. Also, when adding in our own snow in VFX, it’s nice when a practical snowflake lands on an actor’s coat and moves with him. A subtle thing like that would take time and money to recreate in post, but is a detail that could really make the shot look believable.
Check out some more examples in the video above, and see if you can tell the difference between 2D and 3D!
Looking for snow graphics you can use in your own productions? Explore alpha-channel snow footage in the Pond5 collection »
Top Image: Still from Love the Coopers courtesy of CBS Films