The Value of Visual Effects

The Value of Visual Effects

There’s often discussions about the costs of visual effects. But for now let’s take a look at something seldom discussed and that’s the value of visual effects.

What are the benefits of visual effects? - Story telling freedom.
Freedom for filmmakers, writers and directors to tell any story they like.  Humans have been telling stories since communication made it possible. Verbal and written story telling can and does cover everything imaginable. A writer has full freedom to do anything including having their main character turn into a giant cockroach. Myths from around the world describe actions and creatures that don't exist in real life. Even the Bible has a number of stories that would be difficult to realize beyond the written word and paintings.

The various mediums of story telling all have their place and good stories are tailor made for each medium. Converting a novel to a film script takes specific writing skills to boil the essence down to 2 hours. It also means that writer descriptions that would form images in the readers mind now need to be generated in photographic reality for the movie viewer.

Visual effects
Visual effects have been used in films almost from the beginning of movies. Méliès used visual effects extensively in the early 1900's. (More info on Méliès) Since that time visual effects have been used frequently and not just for special purposes. Some movies used matte paintings to add ceilings that were non-existent on the sets. Visual effects continued to evolve and provide sights not viable to actually film. Their style tended to be in keeping with the film styles of the day (shooting outdoor scenes on sets, rear projection, etc). But visual effects were not without their limits. Camera moves and other restrictions were simply due to the limits of the technology at that time.

With the advent of digital and computer graphics as tools for visual effects, artists are now able to have full control over their images in a way not possible before. These are in addition to their toolbox of previous techniques including models and miniatures when desired.

Almost all films coming out of Hollywood use visual effects to some extent and even many independent films have visual effects. Keep in mind that visual effects is not just for science fiction and fantasy films. They can be used extensively in period films and even in present day comedies. FIVE YEAR ENGAGEMENT used visual effects. WAR HORSE used visual effects extensively including some of the field shots, leaping horse, etc. FOREST GUMP showed an actor missing a leg.

Visual effects cover such things as:

Creating entirely virtual shots
Changing the background
Creating the background
Adding actors, characters or creatures
Changing actors
Adding objects or props
Removing objects
Obscuring objects
Specialized speed changes
Fixing problems on the set, adding eye effects, removing wig netting, etc.

The visual effects team works closely not only with the director but also the cinematographer. Working with the production designer we can expand the sets that are built or build sets that would be impossible to build for real. Working with the stunt team we can remove their rigs (car ramps, wires), help to provide the visuals needed while trying to maintain reasonable safety and can extend or create a stunt if it’s not possible. Working with the special effects* team we can hide their rigs if required and expand and enhance what they’re able to provide. Working with the wardrobe department we can expand the capabilities of their costumes when required (IRON MAN, BLACK SWAN, etc) Each of these departments are very helpful in providing visual effects with what we require to get the best material.

Visual effects is normally focused on the augmentation or modification of live action but visual effects artists and tools are also used for:

Computer graphics animated films (Pixar, Dreamworks, Sony Animation, etc)
Video games
Previsualization
2D to 3D conversion
Titles
Logos
Special venues and multimedia (in addition of course to films, television and commercials)

Now to those of you who may hate visual effects or computer graphics keep in mind you’ve already seen an incredible number of visual effects shots and never even noticed. Much of the work done is not over the top theatrics. In many cases it’s to allow productions the option of shooting something elsewhere or to fix problems on the set (boom mics, makeup, etc). Even television shows like Ugly Betty did a couple of years with green screen to place the characters in New York. Unlikely that most viewers even noticed.

Next time you watch a period film consider that many of the buildings you see may not exist or may be currently covered in tv satellite dishes. The bay you see in the background filled with ships was likely added.

Visual effects artists and craftspeople have been developing and refining their tools for decades. Digital Intermediates (DI) is used for color correcting films. These and many of the digital tools that film productions use daily were pioneered by visual effect artists.

So we are now at a point where just about anything that can be imagined can be created on the screen and look good. Realistic when required or fantastical when required depending on the production.

When visual effects don’t look good these days it’s likely:

Too little time (changes or additions to visual effects from the director or studio can happen up to the final week of work). This means there’s no final polish or in many cases not even a chance to do a good take. And these days many productions start with too little time to begin with.
Selecting a visual effects company or people that may not be up to the task or lack experience with specific aspects.
Poor shot design
Poor creature design
Not being able to shoot the required elements as planned
Not enough time on set to gather necessary images and data

Freedom
In the end studios no longer have to leave scripts on the shelf for years because they’re not doable (DRAGONHEART, WATCHMEN, BENJAMIN BUTTON, LORD OF THE RINGS, etc). Directors and writers have complete freedom to bring their imagination to the screen and to tell just about any story in the manor they wish to. At least as far as visual effects is concerned.

The amount of control and freedom for a director is almost unlimited. That along with the fact many movies are concerned with pushing the envelope creates some sequences where the believability is pushed too far. Where the onslaught of in your face imagery causes audience overload or eye rolling. This happens with stunts and special effects when they are pushed too far as well and the audience says ’oh come on’.


Box-office

In addition to allowing filmmakers freedom of story and flexibility to change or modify scenes, visual effects certainly help the studio’s bottom line. Film is a visual medium that can be shown and appreciated all over the world. Visual effects can provide unique worlds, views and characters that ignite the imagination of those that see them. They can provide the spectacle that goes with specific types of stories.

If you look at the top box-office list of 25 or 50 films you’ll notice almost all of them required visual effects and in many cases they are full of visual effects.

Here's US top films
Here's the Worlds top films

Hard to find non-visual effects films, especially in the world list.

Studios choose to visual effects heavy films as tent pole films because they’re profitable. With some of the top films earning over a billion dollars the sum total of successful films in which visual effects played a significant role is staggering.

[Note that I’m not saying all films need visual effects or that the film world revolves around visual effects. I’m a fan of well told stories of all types. I’m simply documenting the current state of visual effects and what the potential is. Visual effects do not make a story better or worse, just that they allow bringing certain types of stories to the movies.]

A world without visual effects
Try to imagine many of the top films without visual effects. STAR WARS without space, spaceships, lasers. TRANSFORMERS without the Transformers. The MATRIX without bullet time and impossible physics. AVATAR without it’s world, without it’s plants, creatures and Na ‘vi. TITANIC without the water and the entire ship. ALICE IN WONDERLAND without the world and characters. HARRY POTTER without the magic. JURASSIC PARK without the dinosaurs.

Look at this year so far - AVENGERS, SPIDERMAN, MEN IN BLACK 3, SNOW WHITE AND THE HUNTSMAN, BRAVE, PROMETHEUS and a number of other films with 5 months still to go.

It’s hard to begin to imagine these films without visual effects. Needless to say these films would have not done nearly as well without visual effects. It’s likely they wouldn’t have been attempted without visual effects. Showing an actor saying ‘You should see what I’m seeing right now, it’s fantastic’, seeing actors jumping around in front of a green screen or painted cyc or adding a Prologue at the start of a film to ignore certain aspects (such as tv dishes in a period film) would not tend to make for a great movie going experience. A play, musical or opera tend to be confined to a live stage and as such the audience accepts the limits as they’re presented. These days however most film audiences are looking for a sense of reality in the movies (even if the movie is a fantasy).

As we can see visual effects provide both monetary and creative advantages to the studios and filmmakers. They play a very important role, especially today, in not only the movie industry but in television, commercials and other content.

Visual effects and the shooting process
Many directors in Hollywood not only accept visual effects but embrace them for being able to provide the vision they need for their film projects. These directors usually get the most out of their visual effects budget. However not everyone agrees. Some directors would prefer to consider effects a necessary evil and put them lower on the priority list, even when working on a super hero or talking goat movie. In this case the super hero powers or the talking goat are likely the key things in the trailer and one of the main reasons the audience is interested to see the movie. But some choose not to acknowledge the value that visual effects can bring to their project.

In some cases the directors don’t interview potential visual effects supervisors but simply let the studios or someone else make that selection for them. Do they approach hiring of the cinematographer and other key creatives in the same way? Unlikely.

The attitude of the director, producer and 1st assistant director has much to do with how successful the shooting process is to the visual effects crew. One of the aspects of creating great visual effects is to shoot the footage correctly for visual effects to begin with. This means typically having the visual effects supervisor and a small group of people to take references. Because we have to create and very precisely combine multiple images together we want to make sure we know exactly where we can place the objects and make sure to light them to match. Shooting references involves holding up a gray and silver sphere in front of camera or shooting with a special camera setup.

When shooting, a large amount of time is spent setting up to get the shots. A 2 hour movie may have a shooting schedule from 40 to 100+ days. Each day can cost $100,000-$300,000 or more depending on the size of the project. Each setup takes time. The grips may lay down dolly tracks or a ‘dance floor’ to shot. The cinematographer spends time lighting the set and the other departments prepare. The audio department records 30 seconds of silence at each location to make sure they have the raw materials they need in doing the final sound mix and edit later. The entire crew is silent during these takes. When an airplane flies overhead it’s likely the crew holds until it passes so they can record good audio. Yet when the visual effects team needs to spend a minute shooting a reference it’s not unusual to get eye rolling and gnashing of teeth. “You’re slowing us down. We’re trying to make a movie here.” are common phrases heard at that time. They easily forget that most of the movie is being completed later in visual effects and visual effects are critical to the success of the movie. As pointed out visual effects may have enabled the project even to be made but some crews look at visual effects as the lower department. On the better projects it’s all part of the process from the beginning and not a problem.

There may be times during shooting that the visual effects crew is not scheduled or have been released for the day. But that doesn’t stop production from sometimes attempting to shoot visual effects on their own. They don’t try to shoot shots if the camera crew isn’t there. They don’t try to do a stunt or start a fire without their respective departments being there.

On shows with a lot of visual effects there’s the notion that anything can be done and that it’s all in the budget. Rather than removing something from set or location (8 x 8 ft silk, compressor, truck, etc) the crew will sometimes ask if visual effects can simply remove it. They suggest they can cover it green as if that provides us the magic fix. If production is running behind schedule, something isn’t working (such as a prop), or hasn’t arrived (contact lenses, etc) then production has a tendency to push that onto the ever growing visual effects list. We barely have enough time and money to do the planned work let alone this ‘extra’ work but since the studios typically have visual effects and live action as different budgets that is not of concern except to those who see the big picture.

And of course the cost of visual effects is brought up frequently.
So why use visual effects (in addition to the reasons provide at the start):
1. It’s cheaper than the alternative. Consider how much it would cost to destroy a city or a planet. Visual effects don’t look as expensive in that context.

2. It offers more precise control. Since time is money on set and the director may want exact control or the option to precisely change it later, visual effects may be the correct option.

3. Not enough time. Maybe you have the money to build an entire castle but do you have enough time to do so before shooting starts?

4. It’s not possible any other way. Floating space ships, talking dragons, people flying and shooting lasers are not exactly easy things to obtain. How long would it take and how much money would it require to build the Transformers? How long would it take to genetically produce a dragon?

Keep in mind visual effects models and environments have to be created from scratch. We can't rent a house to shoot in or props to fill it. We can't rent a field to shoot on. We have to build and paint everything from scratch. When we move our characters or creatures we have to make sure their feet touch the ground without going into the ground or floating above it. Many of the things taken for granted in live action has to be worked out in great detail in visual effects.

Summary
Visual effects allows filmmakers an incredible freedom to bring any story they wish to the screen from a creative and technical standpoint.

Visual effects  are used in just about all films, above and beyond just science fiction and fantasy films.

Visual effects film do very well all over the world. The top box-office films of all time use visual effects and most use visual effects extensively.

Visual effects artists are the only group involved in Hollywood filmmaking that don’t have a union. Most are freelance project to project just like other film jobs. Visual effects craftsmen work long hours like other film people and at times are likely to be putting in 80 or 90+ hours a week for weeks or months at a time due to compressed schedules and last minute changes. Much of visual effects is outsourced around the world due to film tax incentives just like some of the jobs in Hollywood. Some artists have to uproot their families and move to other countries in an attempt to remain employed. I believe to get the best out of people you should respect them.  Given all that visual effects brings to films, the people who make them and the people who watch them, I think visual effects artists deserve the same respect as the other departments and workers in the film industry.

Related Post

The Miracle of Visual Effects, will it continue?  - images show what visual effects can do

Why do Visual Effects cost so much?
Visual Effects are Inexpensive


*Special effects are explosions, breakaways, wire rigs and other on set work as opposed to visual effects which is about images and primarily done in post-production.

Designing Visual Effect Shots

Designing Visual Effect Shots, Part 1

(This posting started getting very long and cover a lot so I’m breaking it into smaller postings. I’ll get into more specific details in future postings.)

The success of a Visual Effects shot is not only dependent on the technical aspects of the shot but also the creative aspects. It all starts with the initial shot design.

A well designed visual effects shot will have impact and help to tell the story clearly. A poorly designed shot may confuse the audience and at the very least will squander an opportunity. A poorly designed shot can actually cost more if the studio or director decides in the edit stage that it’s just not working. At that point the shot could be re-shot with a better design (unlikely) or many attempts will be made to fix the shot in post without a clear understanding of the problem.

Note that the design criteria for visual effects versus normal live action shots are primarily the same. The differences with visual effects shots are:

1. Usually the entire visual effects shot is not visible or apparent at the time of shooting. Images will be added later or the existing image will be modified. This requires pre-planning. A live action shot is usually working or not working on the set. If a camera angle makes a stunt look boring then they’ll know that when reviewing the video on set.

2. On live action the Director of Photography and Camera Operator are focused on the look of the shot in addition the director. The director respects their opinion. With visual effects the director and a storyboard artist may have designed the initial shots before the visual effects people are even hired. How much influence the visual effects supervisor and his team have on shot design depends greatly on the director and how much respect they have for the visual effects process. The better directors understand this and take advantage of the visual effects team.

3. Visual effects sometimes deal with design issues that don’t come up directly in live action. How to show the scale of smooth object floating in space? How to transform this paperweight into a creature?

4. Visual effects can be much more limitless. With live action you have set and equipment restrictions which may prevent you from doing certain types of things. A visual effects shot can have more freedom of action, movement of camera and lighting effects.

5. Visual effects can require a deft hand of design and editing just as a comedy sequence requires some finesse of timing, angles and specific phrasing.
Spider

Below are some of the many issues to keep in mind when designing a visual effects shot. These aren’t rules, just a set of suggestions.

Does the shot help to tell the story?
This should be a fundamental of any shot or scene in a film, whether live action or visual effects. Sometimes visual effects are only used as eye candy. The director wants to wow the audience with a car crash, explosion or a visual effects shot. If that can be done and still work to tell the story then that’s great. If it’s only purpose is eye candy to wow the audience then it may be a lost cause.

Audiences these days have seen a lot visuals between films, tv, video games and the internet. They’ve come to expect something new and different. Visual Effects are not as special and magical as they once were to the audience. There was a wow factor in the early days of computer graphics when things were new. It becoming more difficult to find techniques that provide the wow factor. Shot design is a major factor to making the wow factor even using standard techniques. As a case in point, THE MATRIX used ‘bullet’ time and most people thought this was the first use of it. There had already been at least one movie with the same effect (LOST IN SPACE) and a few commercials but the combination of art direction and design combined with the story made an impact.

Even in the early 80’s people thought much of what they saw was computer graphics. A number of visual effects commercials were designed to look like computer graphics even though many of these were done by traditional animation techniques. Logos would fly through the air with metallic glints. These were all done with a number of pieces of artwork and passes on an animation stand. For ESCAPE FROM NEW YORK at Dream Quest we used physical models of building painted black with white lines.

What is the point the shot has to make?
Maybe it’s to establish a castle or to show a creature emerging from a box. Whatever the reason it’s important to keep that in mind throughout the process. Given the length of time from the initial design to the completed final, the shot can veer off course quite a bit.

At the time of shooting someone may have a ‘better’ idea. Why don’t we frame it like this? Why are we wasting all of that frame area there? This is when the visual effects supervisor has to remind them that the empty area on the side will hold a creature in the final shot. Another reason why storyboards are essential is to provide a clear visual of the final shot. More likely it will be a subtle change that will have a big impact later. (Let’s put this prop here, lets add a real explosion in the foreground.)

In post production the editor may want to reframe the shot or use a different element entirely. The compositor may put in more smoke in the foreground. Everyone involved in the shot (director, supervisor, animator, technical director, etc) are likely to be focused on the details and lose sight of the purpose of the shot. In an attempt to make the shot even ‘cooler’ you lose the focus of the shot. It’s only when it’s cut in will the real problem become obvious again. The reason for the shot may now be so obscured that the audience will be confused and lost. If that’s the case it throws them out of the movie. Try to always review the shot in context and take a step back to check the intent of the shot.

Does the shot fit in the movie? Does it fit into the sequence?
Unless it’s a specific dream sequence, most visual effects shots are supposed to blend into the rest of the film. This is true whether it’s a period piece or a science fiction future thriller. The design of the shots, the camera motion and the lighting should match the live action. If you have a hand held action sequence and cut to a locked off visual effects shot, then it will stand out.

My suggestion to directors is to design the shots as if everything is really there. How would you frame and shoot this in live action? There’s a tendency to treat the design of even simple visual effects as different than the rest of the film. “We’re paying for the shot and by gosh we’re going to show it off” is sometimes the approach taken. If it’s a real building they might frame it from a ¾ angle and not make a big deal of it. If it’s a matte painted building then it’s likely to be designed to be shot straight on with clouds added to the sky. All of those are clues to the audience that something about the shot isn’t right.

It’s possible for a disconnect to happen since the director usually sits down with a storyboard artist months before shooting. These shot designs may be a different aesthetic than how the director of photography approaches the live action. The director is involved with both teams but there are thousands of choices to be made that may place them out of sync. There may be times a second unit director is approaching the shots differently than the main director. Sometimes in post the director realizes he can change a lot, especially on a virtual shot Focusing on a hand full of shots may cause them to shift away from the rest of the film.

Adjust the design of the shots based on their context and what they’re supposed to accomplish. If they’re supposed to be realistic backgrounds then all the more reason to fit them into the rest of the movie and avoid drawing attention to them. Once again, how would you treat this if it really existed? If it’s a dramatic effect then design the shot to take advantage of that and push it within context of the film.

(more design posts to come)

Filming

Filming live action for visual effects on feature films. I discuss the process of shooting on locations and sets, using references, creating interactions and things to watch for. In addition I give some suggestions of to apply this to low budget filmmaking.
I'll probably discuss moving cameras and matchmoving in the next podcast. Filming of bluescreen, minatures and other elements will be covered in future podcasts.

Transcript
In today's podcast I'll be covering the filming process relative to visual effects. First I'll focus on how it's done on a feature film and at the end I'll provide additional suggestions for filmmakers. I've actually split up this podcast so moving cameras will be discussed in the next podcast.

There are infinite possibilities when shooting a film, which is one of the reasons why visual effects are interesting. I'll be covering the basics of shooting with actors or what we term as live action. Later podcasts will discuss shooting bluescreen and miniatures.

First a review of a few terms I'll be using.
CG stands for computer graphics.
An element is an image that will be part of a composite.
A plate is a live action element.
A clean plate is a version of the shot without actors that can be used to remove any unwanted items from the real shot.

The shooting of a feature film can take two to six months. Much of the shooting depends on the project. Some projects such as Dragonheart are shot almost all outdoors, regardless of weather. This makes it like a camping trip with 2 or 300 hundred other people. Other projects may be primarily on sound stages in front of bluescreens. Most projects are a balance of exterior and stage shooting.

Prepping for the shoot
Before shooting begins it's important that the cameras are checked and prepped. This is handled by the camera assistant but for visual effects we request a steady test. When film goes through a movie camera the camera movement may cause the film to shift a bit from frame to frame. This isn't visible in a typical shot projected on the movie screen but if you composite multiple images you may well see them moving against each other. In some older movies when you watch the titles you may see them shaking against the background. This was because the original camera wasn't completely steady.
To test the steadiness a grid of white lines is applied to a black backing. This can be tape lines on a 4 by 8 foot black. This is filmed with the camera fixed on a tripod or pedestal. Depending on the test the film can be rewound and re-exposed to the same grid offset halfway by a grid space. When this is processed and projected you can see if the camera is steady and repeatable to itself. The preferred steady test is to scan the grid from the camera with your film input scanner and confirm that it's not moving relative to your control system, the input scanner.

Film live action for visual effects

The visual effects crew directly involved with the shooting is fairly small. Normally the team consists of the visual effects supervisor or a plate supervisor, 1 to 4 matchmovers, a coordinator and possibly the effects producer as well. If the show is heavy with animated creatures the animation supervisor may also be part of the team. The remainder of the visual effects crew is back at a facility working on creating CG and real models along with preparing for the full render and composite processes. The full effects crew won't start until a sequence has been shot and edited since they need to work with the footage. Because of the deadlines most shows are editing simultaneously with the shooting so finished edited sequence will be done even before the entire movie is finished being shot.

The visual effects supervisor or plate supervisor is in charge of making sure the required footage is shot correctly to do the effects later. The plate supervisor is called that since live action pieces or elements are frequently referred to as plates. A background plate for a bluescreen would be called BG plate. The matchmover position was created primarily in the digital age. It's important to be able reproduce the camera and objects exactly and that means recording all the camera information such as lens, tilt and also to measure specific items in the scene. The coordinator helps to organize all of this and to facilitate passing of information. The effects producer is normally busy at the effects house overseeing that process but the production itself may have their own effects producer on the location to help the different departments and to make sure things are moving smoothly.

Before the photography begins there's usually some pre-production at the location. Part of this is a key meeting with all the department heads, including visual effects, so everyone is clear on the requirements of each sequences and who's doing what. It's also a chance to flag any problems. Typically the storyboards and animatics are shown to the department heads and the actors so they're aware of what the final shots will look like.

Each day there is a call sheet passed out to all crew members that lists the shots/sequences for the next day as well as when each crew member is required on set. A shooting day is usually 7am to 7pm and night shooting is 6 or 7 pm to 7 am. Shooting is 5 or 6 days a week.

The setup
First thing in the morning is brief huddle of key personnel with the first asst director and director. The director has his shot list, which is the list of all shots he plans to shoot that day. For shots that require visual effects the first task is to figure out the camera position and blocking. A director may run through with the actors first to get a handle on how he wants the scene covered. For camera placement it's important to consider anything that will be added later in postproduction. I typically have a set of storyboards that have been reduced to half size so it fits in my side bag or jacket pocket. I've gone through and made notes about every element or piece of film we have to shoot for each shot and have a technique in mind for each shot. We do a quick review of the storyboard. Since the storyboard is only a guide the director or circumstances may require a change. As a visual effects supervisor I have to be able to quickly determine any implications these changes might mean. Will other elements be required? Does this change the technique? Have we already shot something else that this needs to work with? Will there be any major cost differences?

For Dragonheart I wrote some software for a powerbook that would display the dragon in the correct size on a location still, but we found it faster to take the poseable dragon model in front of the camera. With the actor standing in the scene and the physical model of the dragon we can easily check the composition and framing. I'd have a matchmover measure the distance to the actor and would calculate the scale distance for the model. If the actor was 50 feet away it might mean the model should be 23 and ½ inches away. Now the director, DP and myself would review the framing. Once the initial framing is setup we review the specific storyboard and animatic with the camera operator and actors along with key people. The practical effects and stunt crews start any rigging necessary while the director of photography lights the scene.

To help the actors and the camera operator interact with a creature we try to provide a stand in. For Dragonheart we had a monster stick that was an expandable pole with 2 disks on each side representing the eyes. For something like Mr. Hyde on Van Helsing a 2d foam core cutout was attached to a helmet worn by an actor for reference. Roger Rabbit used 2d cutouts and full-size 3d practical model. If the creature is moving someone moves the stand-in around. The actors can use the eyes as a guide where to look and react and the camera operator can make sure they provide enough room in the film frame for the creature. At least one reference is shot with this stand-in moving around. This can be used as a temp in the edit stage since the action and framing is clearer with the reference. We try to do the majority of takes without the reference to avoid having to do paint out removal of it in post. In some cases though the complexity of the action may require the stand-in be in all the takes.

Interaction
Any time you're combining multiple images you want them to blend together to make them appear to be a real scene or location. To help with this illusion we try to provide interaction of the different elements such as a creature that lifts up the actor and then swings it's tale to knock over a bookcase. This is where the special effects crew gets involved. As mentioned before technically special effects in movie credits are practical or mechanical type of effects. Normally this will have already been discussed with the special effects supervisor who will have planned and constructed some type of rig to do this. If it involves moving the actor or a stunt person then the stunt coordinator is involved. New ideas from the director at the time of the shoot require everyone to scramble to make it happen. If it was preplanned and there is an animatic we use that as a starting point for the timing of the action. If there is no animatic the animation supervisor or the visual effects supervisor is involved in working out the timing with the director. We need enough time for the actor and the imaginary creature or object to react. The asst director will usually provide a verbal cue so the special effects crew can do their part at the right time. If the creature is supposed to speak then someone on the set will be a stand-in for the creature by speaking off camera or this may come from a pre-taped voice. An actual person on the set delivering the dialog is preferred since the timing and dialog can change easily.
Another form of interaction is the lighting from the director of photography. If colored objects are supposed to emerge from a glass then the DP has to create an interactive light on the faces of the actors so when the objects are added later by the visual effects crew they look like they're creating the light effect on the faces.

Rolling film
Each shot and take is noted on the camera report and slated. For visual effects shots there are usually specific shot names or ID codes that relate to the sequence. These names may have been defined months before in pre-production and relates to specific storyboards.
The first take is usually done with any interactive reference material as monster sticks or a stand-in. After that the shots may be done without these depending on the specific requirements.
During each take the visual effects supervisor is making sure everything is working as required. Is the actor's eye line correct? Is he looking for where the creature will be in that specific moment? Has he missed a mark and put his arm through where the creature is supposed to be? Are there additional items that may need to be removed? Will the special effects rigging work and will everything look correct once the shot is finished in post? Are any cables causing a bunching up on the costumes that give away the fact the actor is on wires? Is the camera move correct and timed right? There are a hundred items to keep an eye on.

The actor's eye line becomes even more difficult when there are multiple actors. If you have a lot of extras it becomes very difficult. If you have a small object flying and hovering the illusion won't work if everyone is looking in a different direction. So to handle this you do the run through with the reference and may need to shout out timings so to choreograph this eye motion. You may need to work with the special effects people to create a small target that can be moved around that people watch. For Dragonheart we used an ultralight plane for some shots where the dragon is flying. This provides everyone with a clear idea where to look and the plane itself is removed in post.

Multiple video cameras may be mounted on tripods to provide additional reference for the animators and match movers.
I try to list on my storyboard book any additional items that may be critical to keep an eye on in a specific shot. I've also listed the additional elements that may be required.
Most of this checking involves looking at a video monitor coming from the video camera mounted in the film camera. This is known as a tap camera and unfortunately the quality of the tap cameras is about the same as surveillance cameras. The video monitor itself is at what's known as the video village. There's an operator who runs this and records video of the different takes for reference. It's around this small monitor or two that the director, script supervisor and other key people may be grouped around during a take.

If there are changes to be made the effects supervisor discusses this with the director. Normally you let the director be the one giving directions to the actors to avoid confusion.
Once the director is satisfied with the takes for the main action any additional elements are filmed. This may be the clean plate as previously discussed. This could be some practical effects such as dirt hit or an additional actor. For things like dust hits a black flat may be placed behind the dust and this element would be screened or lumikey in the final composite. If it an additional actor this may be shot against a small portable bluescreen on the location. One of the advantages of shooting these elements on the location or set is the lighting will match and camera position will match exactly. Trying to re-create sunlight months later on a stage and have it match is very difficult. The downside is this will take up more time when shooting the live action.

Once any additional elements are shot references are shot. For 3D work normally a ½ of a gray sphere is shot. This will provide a controlled reference for the technical director who lights the CG scene later. It shows where the light is coming from and the basic balance of the lights. A ½ of a chrome sphere, which may be the other side of the gray sphere, is filmed. This will provide an image for the reflection map that is wrapped around the image. This provides some of the ambient illumination as well as image for the reflection. Sometimes stills are taken with a fish eye lens to provide this same map.
A color card or grayscale may be filmed to provide a color reference. I usually try to have a reference of the object that will be added later. If we're adding a CG version of a clock such as in The Mask I'll move that through the action so the technical director, also known as TDs, can use as a guide for how the material and lighting interact. If there's a creature the model shop may provide a reference material such as section of fur if this is a creature with fur. By trying to have as many real world references as possible the final results will be based on what it would really look like in that environment. Even with fantastical creatures the aim is to make them photo real. It's actually more important to make them photo real since the eye and mind knows it's not real it tries to find any discrepancies.

So finally we have one shot done. There may be another 20 more to do that day, each with their own concerns and rigging. On a large show they may be running 2 cameras all the time to provide more angles and coverage. For complex action scenes they may be running 4 or more cameras at the same time. Any of these shots that will require visual effects will need to be watched and measured. A large film usually has second unit crew shooting additional scenes or pickups and inserts at a different location. Each of these shots has to be dealt with the same way if there are any visual effects.

On a large effects film there comes a time when the crew along with the director and assistant director start assuming that you can fix everything and they may become a bit sloppy about removing things from the scene or making final adjustments or providing you what you need. There is always pressure to keep moving on a film shoot and in some cases it will be cheaper for you to do something in post rather than taking an hour at a cost of tens of thousands of dollars to do it on location. The visual effects supervisor has to weigh these two issues and choose his battles wisely. If the quality will suffer because of production shortcuts then it's critical to flag the director and discuss the issue.

Low Budget
So how can we apply all of this to a low budget filmmaker? As always planning and preproduction are vital for keeping production moving smoothly and keeping the costs down. Make sure the effects are there to tell the story.

Try to do a rough storyboard of all your effects shots. Don't get wrapped up in created elaborate animatics or 3D storyboards. Usually the added value of these, especially for simple projects, is minimal but the time required can be enormous. It's better to put your additional time and energy into the real shot.

Analyze the different elements required to make the final shots. Remember to keep it simple. If you can do it using 2 elements instead of 5 do it with 2. List those elements with the storyboards.

Keep the storyboards with you while shooting and check off the elements as you shoot them.

Do tests ahead of time to check your technique and to determine if there are other requirements when shooting.

If this is a really low budget film you may be directing and running the camera in addition to doing the effects. This makes it even more critical to have a checklist and make sure everything is shot correctly.

Communicate with your crew so they understand what you need done. Make sure the actors understand what's required of them. The storyboards will help here.

Don't rush the shoot. If you don't get what you need or get poor quality elements then you're likely to spend a lot of time in postproduction just to create something marginal.

Be prepared. Have your tools with you. Storyboards, notepad, pens, tape measure, etc. A fanny pack or other bag is useful to hold these items.

Slate and label everything. Try being organized. When you're doing effects work you may end up with several elements for each shot. It's very easy to get overwhelmed but al l the different variations. On a feature film we have people who's focus is to keep track of all these bits.

Double-check your camera settings. If you review the footage on your video camera be sure to cue it up to after the last take. This is to avoid recording over a shot and to make sure the timecode is correct if your camera supports timecode.

Just because you can do something in post doesn't mean you should. As an example if someone left a c-stand in the shot you could paint that out later but why bother when you can just take 5 minutes and move it out before shooting. Don't try to fix everything in post. Balance the time on the location with the amount of work required and the final quality.

Keep the shots simple, especially if this is one of your first projects. Even when on set make sure you're not making things too complicated. When we were filming the The Mask we had planned a wide shot where large props are being pulled out of Jim Carrey's pants. Since this included items such as a tuba and bazooka and we saw his entire body we were going to make CG pants and stretch them to show the objects being pulled out. On the night of the shoot the director changed it to a cowboy framing, which means the bottom of the frame, is between the knees and waist. Jim's costume was a very baggy zoot suite so the stretching pants gag became un-necessary with this framing and costume. I suggested we cut the pants to make them into shorts and cut holes in the pockets. We then had two people shoving real props up into the pant pockets.
We eliminated an effects shot and had something that was better for that shot.

If you're shooting on film, especially 16mm, do steady tests before shooting or your images may jump against each other. If you're shooting film but will be finishing on video make sure the telecine is done with a solid movement. In the past you had to request a special pin registered transfer but film movements have gotten better. Just check with the video house and make sure to steady test it.

If you're shooting video try to shoot progressive if you can with a camera like the Panasonic DVX100. You can shoot visual effects with a standard video camera but the interlacing makes the process a little more difficult. Likewise if you're planning to shoot video and doing a lot of greenscreen work consider shooting on a higher end system than miniDV. You can do greenscreen with miniDV but a higher end system will provide better quality easier.

Shoot your shots as locked down cameras if possible. This will simplify most effects a lot.

Try to shoot a clean plate when possible. To make sure there's a good match you can just keep the cameras rolling and have the actors leave the scene. This avoids the chance of the camera changing or the lighting changing as the sun moves.

If you're going to purchase a composting software try to get one with motion tracking. If you're in school check on educational pricing for all software. And certainly take advantage of cameras that may be available through your school.

High quality visual effects takes a lot of time and work. Even with all the tools available nothing is as simple and easy as you would think it would be. Accept that and keep moving forward.