Tuesday, June 26, 2007

Preproduction 9: Special Effects Considerations

Well, ok, the special effects in Sisu don't feature anything quite as dynamic as this graphic - but it is cool, isn't it? Amazing what a girl can do with three minutes and a Photoshop smudge brush!

However, I have my own brand of challenges, as there will be a significant amount of CG (Computer Generated) imagery, most of which shouldn't be visible to the viewer, which in some ways makes it harder to pull off than big explosions and melting aliens. The old saying of course is 'fix it in post' but I once heard a very smart man say 'fix it in pre.' So I am doing everything I can to prepare for the special effects shots so that we get what we need while we are on location. Here are some of the shots I am working on this week.

First, there is a scene in the film where Tom watches the resurrection of his ship, which happened about 30 years after he died. The keel and hull were mounted on a couple of flatbed trucks and driven across the prairie, fulfilling a prophecy Tom made from his death bed. Here are a couple of boards Raul mocked up for me of this scene:

The question here is, as building the big pieces of the boat is pretty cost-prohibitive at this level of filmmaking, can we use CG to help create this scene? A cool friend of mine, Scott Hankel, a compositing genius currently living in Los Angeles, told me that we can create the keel and hull on the back of the flatbed trucks entirely in CG, and in fact, as long as the camera is locked off, we could use a still (a 2D Photoshop graphics rather than having to work in 3D), and animate its scale and position in a compositing program. This would make the shoot much easier and even the post simpler. The only thing we have to do is to make sure that there is some part of the truck, such as the edge of the flatbed, that is seen in the shot so that we are able to track the motion of it for this to work.

Here's the next problem: We have a scene with a big dust storm. Here is what an actual dust storm looks like. I'd love to have that wall of dust effect as the wind picks up.


Here are the boards for the scene, created by the awesome Raul Viceral, Head of Story and Production Designer.

Tom 'astral travels' from his hospital bed as he imagines the scene at his son's funeral, more than 10 years before, which in the script happens right as the Depression and dust storms hit, so the idea is to use no words but tell this sequence of events visually as Tom envisions it through the dream-state as he hovers between life and death on his final day.
Tom approaches the coffin. His estranged wife and daughters, almost in another time/space dimension, do not see him.

Shot of the coffin lying in the middle of the dirt road on the prairie.

Tom looks down at the coffin.

He looks up as the wind begins to pick up strength.

A dust storm gathers on the prairie.

Tom fights the wind.

Long shot of Tom and the coffin; the family has disappeared.

The dust and wind blow Tom and he staggers backwards.

Tom throws himself over the coffin.

Dust overtakes the scene.

Now from conversations with Scott and Andrew Britt, another cool friend of mine from the Bay Area who teaches particle effects at Ex'pression Digital College where he is the Department Head of the Animation and Visual Effects program, there are quite a few ways to go about making this series of shots work. First, it seems clear that we are going to need some practical dust on set, along with a generator and a huge fan, not only to create wind, but also to blow gallons of dust around in front of the character.

As for the effects, which I will be worrying about much later when I get into post production, we can use entirely digital CG particles or we can use something Scott was explaining called 'water tank' which is a practical effect, where you fill a tank, like a fish tank, full of clear water, then you shoot while you dump in some other liquid, like milk or paint, then you take that footage into After Effects or a compositing program, alter the color to match your shot, and place the swirling churning result into your footage. You should put black duvateen behind the tank so you are shooting against black, so that you can get, as Scott describes it, "dimensionality of the liquid as it unfolds in the water." You can also work with CG effects, completely fabricated particles that you program to behave in certain ways, with a certain weight and impetus.

Have your eyes glazed over yet?

Right now I am just worrying about trying to get as much useful stuff as we can during the live shoot so after talking to these guys I think that shooting the shot a few different ways will cover all bases. First a clean plate of the prairie scene with no actors, both the long shot and I guess the close up, then both of these again but with dust being blown around in front of the camera. We'll also take another version with the actor but no dust, and then finally the actor with the blowing dust all in one scene.

My professor, the brilliant Gerald Saul (link to his blog) who has been helping me all term with the storyboards and the shots, had the idea of blowing practical dust around too. So I guess the next step is to price generators and big fans and find some dust somewhere.

Another fun piece of CG work will be this shot of the keel and hull on the prairie. Hopefully this one will be relatively simple as the shot is planned as being somewhat in silhouette.


Here's another shot that Raul thinks will be more or less simple to do. In the final film this might actually be a barn, not a house, which every time we see it is coming down more and more as Tom dismantles his homestead for materials for the ship.

Other CG scenes include these three, which feature the 3D model of the ship that will hopefully be built by another one of my ultra-cool and talented friends from the Bay Area effects world, artist and digital modeler Howie Weed (Star Wars, Terminator 3, War of the Worlds, AI, etc. etc.). Here is a shot that we don't have boards for yet but I do have this early concept painting of, with the ship flying off into the prairie sunset. The background will be the actual prairie sky with one of those incredible Saskatchewan sunsets.


Here is the same ship, rocking on top of a hill, riding it as if it is riding the waves.


And here it is seen through the window, casting a golden glow on the face of the child Tom Sukanen:





For all of these CG compositing shots, we need to think about matching the lighting and the color on the imported CG elements. For this purpose, Scott Hankel says we should do a good job of recording the settings while on location. First, he says to take an HDRI (High Dynamic Range Imaging) photo of the set, meaning you take a normal picture and then bracket it 5 stops up and 5 stops down; in other words you take ten pictures of the same thing but with different exposures. He also says that for any shots where we might use 3D CG elements, we should take some video footage of a mirrored sphere (apparently you can get these at garden shops) and some also of a matte grey sphere (he says you can get plastic ones and spray them with an 18% grey paint). This footage will somehow be useful later to the CG artists or whoever is trying to match the lighting and the conditions from the day of the set in the color and levels of the imported CG element. Good to know!

Here's a picture showing how you use the mirrored sphere to document the lighting conditions for the 3D CG shots:


The above picture came from this cool tutorial link at Max Realms; check it out for more information about the coverage we'll need to get on set for the 3D CG shots. This stuff makes my head spin but it's a great link for geeks or anyone who wants to make sure their compositing will go smoothly! I guess I fit into both categories (sigh).

Another interesting dilemma is this shot of Tom's threshing machine that he is designing. Once he gets it on the wall, it begins to animate. Thinking through how to do this is interesting. Raul and I have talked about the animation being done in pencil, then scanned or shot frame-by-frame, and then brought into the footage using After Effects. The only thing we need to consider on set is getting a clean plate shot of the scene without the actor standing in front of the plans.

It's great to know people who know about these things so that we can get full coverage on set of what will be needed later to make the effects work. I had a sneaking suspicion that we should be thinking about these things now and it turns out that was a good suspicion to have.

And I really didn't believe it, but I guess people do buy ornamental mirrored spheres for their gardens. Below is a pic from an ornamental garden supplies website. This must the most amazing thing I have learned today!


Now I have, at times over the past year, heard some opinions expressed that all good films should end with a huge explosion, and I should try to work that into this film somehow. If I do decide to go with the explosive ending, armed with my new Special Effects knowledge it should be a snap!


Of course I am kidding.

Until next time... Sisu!

2 comments:

Anonymous said...

This post rocked, but you broke my heart at then end. Even so, I can't wait to see how the effects turn out. Everything looks great and I love the blog!

p.s. Glass fish tanks have a noticeable blue-green tint. You probably already knew that and I'm sure you can adjust for it, but just in case... fyi. Acrylic tanks won't have that tint, but they scratch easily and are more expensive.

Anonymous said...

Chrystene;
There's so much to learn from this blog!
The main question for me is: where did you find these mirror balls? and....glad you're skipping the explosion...
Looking forward to see what comes next!