SAVE VISUAL EFFECTS

Eliminate the politics and help make visual effects a stable industry and a viable career option for global workers.

Support ADAPT.


ADAPT web site

Sunday, November 27, 2005

Moving Camera

Using a moving camera when filming live action for Visual Effects.
Locked off camera, Post Moves, Motion Control, 2D Motion Tracking, 3D Match Moving and Face Markers are all covered in this podcast relative to live action photography.
Approx 25 minutes.

Transcript
Today I'll be discussing the moving camera.

Locked Off
The simplest type of camera move is no move or the locked off shot. The camera is placed on a tripod or dolly and isn't moved. This makes it easier to add visual effects later or to do multiple elements of the same setup. Examples of this could include adding a matte painted house to the top of a hill. If you wanted to create a shot where part of the actor is removed later – such as a leg as in Forest Gump or most of the body as in the invisible man you would shoot the shot two times. Once with the actor and another time with no actors. This shot with out the actors is called a clean plate and is pretty common for many visual effects. Because the camera doesn't move you have identical images – one with the actor and one without. In post production if we remove part of the image of the actor the clean version gives the image without the actor. Special rigs are removed the same way. This same process is easily used for creating twins from one actor. Shoot the scene once with the actor on the left side and then shoot the same thing with the actor on the right side. Because these shots don't change position you can do a simple split down the middle of the scene.

Normally the camera operator is making slight pan and tilt adjustments while sitting on the dolly and the asst cameraman is making slight focus and exposure adjustments. To obtain the best quality of clean plate get everyone away from the camera, off the dolly and avoid changing the settings, even to do slates. The size and position in frame will be different if anything changes, including the exposure. You can spend time fixing this in post but it's better if you can avoid the problem.

Even though a locked off camera makes it easier to accomplish visual effects it may not fit with the look of the rest of the film or the requirements of the shot.

Post Move
Doing a move on an image in post is sometimes called Pan and Scan. This also can refer to transferring a widescreen film to full frame video.

The scene is photographed normally and then in the composite stage the image is enlarged and a synthetic move is added by moving the image digitally. It's also possible to do this type of move with some scanners for better quality.

The problem here is the loss of resolution from enlarging the image. If your end production is video then it's possible to scan the film at a higher resolution.

In the past another way around the resolution problem was to shoot on VistaVision or 65mm cameras. VistaVision a format which shoots with special cameras that run 35mm motion picture film sideways, much like a still film camera. This larger film size allowed for blowing up without as much quality loss in the days of optical printing. Large formats were also common when doing any effects heavy productions in the days of optical compositing. 2001 A Space Odyssey, Close Encounters and Blade Runner are some of the films that used 65mm. Star Wars and most ILM films used VistaVision for effects until the last few years

If the live action element only makes up a portion of the frame then a post move doesn't cause a quality loss. An example of this is starting on a scene which is all live action and then pulling back to reveal a large matte painting extension to the scene. In the old days a motion controlled camera might be used to film a physical matte painting on glass. A rear-projector would be one method of adding the live action with the same move. With the advent of digital matte painting the matte painter creates the painting at a higher resolution. If the original live action scan is 2000 pixels across, the matte painting might be done at 4000 pixels across if the final scene was going to show twice as wide.

I'll discuss 2D match-moving later in this podcast, which is a form of post move on an element.

One of the problems with post moves is the very limited 2D or two-dimensional appearance of the moves. There's no perspective change or feeling of depth. To obtain true 3D camera moves of the original live action there are a couple of processes.

Motion Control
One way to deal with this is using motion control. Motion control is used frequently with shooting miniatures and models but here I'll focus on live action use. Normally the camera is mounted on a pan and tilt mechanism known as a camera head. The operator has a hand wheel for pan and one for tilt. For motion control you have a special head and usually a special dolly where all of these motions are controlled by motors. In some cases the operator moves this just like a regular head and a computer records the positions by using position encoders. In other systems the operator uses a joystick or a remote camera head that is designed to just record his hand moves. In this case the remote head looks like a camera head but it's just a box with the hand wheels.

Note that non-recording remote camera heads are also with live action frequently when the operator can't be at the camera itself. The camera is on a boom arm or other remote system where the operator watches a video monitor and remotely controls the camera.

With true motion control once a camera move has been programmed the move may be repeated over and over again exactly in sync with the camera. The repeatability means you can shoot the same actor walking through the scene multiple times with a complex camera move. This would be done to create twins using one actor during a camera move. Motion control also allows you to film moving clean plates so you have many of the same benefits as a locked off camera such as rig or actor removal. Since the move is recorded you can also take this data and use it later in a motion control system for models or convert the data and use it in the computer for adding CG elements.

Motion control can also be used to shoot secondary elements such as bluescreens people or objects that exactly match a previous live action plate. In this case the data for the move comes from the original motion control shoot or from a process called match moving, which I'll be covering shortly.

The downside of motion control is the requirement for a special system that has to be setup and be programmed. Most directors hate it because of the extra time and process. I recommend it only when you really have to get repeatable motion on the set or location.

I'll cover more details of motion control in a future podcast.

MatchMoving
The other option when a moving camera is required is to do matchmoving in postproduction. This is now one of the most common techniques that came about with the advent of the computer. The simplest technique is shot with just a pan and tilt that requires another images to be added later in the composite. As an example if we pan and tilt an outdoor scene and wish to put the image of a flying saucer hovering we could matchmove a point near the horizon or infinity like a distant mountain or building.

This is done after the film images have been scanned into the computer. These days' most professional compositing programs allow you to specify an area in the moving footage that you want to track. Frame by frame the computer compares the image in this area and tries to find the best fit around where it was last. We call this 2D tracking since it's only calculated in 2 dimensions x and y.

Once this is done the image of the flying saucer is composited over the background and the motion of the background is applied to it. Now you have a scene with a pan and tilt of a cityscape and a flying saucer that hovers over a building no mater what move you make. This creates the illusion it was there the time of photography. If you have 2 distant points that you can track then it's possible for the computer to calculate the rotation and size so you can not only pan and tilt but roll the camera and even do some basic dolly or zoom moves. I suggest distant points to track so you can obtain a more accurate motion track without having to worry about parallax or perspective. You typically also want to track a point in the scene close to where you want to place the additional image. Make sure you always have at least one or 2 points in the scene to track during the entire scene. If you're doing a big pan move make sure there's another suitable point that you can switch the motion tracking to during the shot. Ideally these would be close to the same distance away from camera.

Even though this is a 2D track it's possible to obtain 3D pan and tilt information. By knowing the lens used to photograph the scene the computer can calculate and output a 3D camera file that can then be used in 3D program for the 3D camera to pan and tilt. This renders an object that matches the move exactly.

Another variation on the 2D tracker is a 4-corner track. If you have a billboard in a moving shot and want to replace it with a different image you could track each corner of billboard on the computer and tell it to apply the move to each corresponding corner of the new image. This will distort the new image to fit it in the billboard even if the original scene is moving.

3D matchmoving
The next level of match moving is 3D match moving.
When shooting a scene measurements are taken of any landmarks in the scene (windows, doors, tables, that sort of thing) and in some cases special markers are placed in the scene. Later after the film has been scanned into the computer a person called a matchmover will build a rough replica of the set or location in the computer. The virtual camera, which is a simulated camera in the computer graphics program, is now animated to match the move of the film camera that filmed the live action scene. Originally this was done as a manual process of lining up the CG set with the image from the film. Now much of it is done using special 3D motion tracking software.

Note that some measurements such as the focal length of the lens may be a bit different than marked. If it's labeled as a 50mm lens it could in fact be a 48mm or a 55mm lens. As such you may need to make some adjustments manually to get the final matchmove perfect. Also be sure to check any automated 3D matchmoves since it's possible to fool the computer.

Now that we have a CG camera that matches we can now place a CG object such as a box on the match move floor and it will look like it was on the floor in the original photography. It still has to be lit and composited into the scene but it stays locked with the correct position and perspective in the scene even if the camera operator is moving a hand held camera around the imaginary object.

If a CG creature will be walking on rough terrain hopefully the matchmover has been able to recreate that so the animator can always keep the creature on the ground. This terrain shape is likewise used to cast CG shadows onto. The matchmover has also included any large objects such as tables and trees so the animator can avoid those when moving his creature. If the actor in the scene is interacting with the creature then the matchmover moves a CG pawn that represents the actor. In some cases the matchmover has to do a very tight match of the arms and legs of the actor so the animator can time and match the creature to the actor. Even though I'm using the term creature this could be any 3D object or effect such as CG sparks.

So now that we have the basic of the matchmove process down lets take a look at how that works when we shoot. If you're going to be using 2D tracking then survey the scene and make sure you have some definable points. Any place of sharp contrast or a spot. The corner of a building against the sky provides a clearly defined area that is fixed. The edge of a tree blowing in the wind is not a good point since it's changing. The edge of a building isn't a good point because it needs to be one specific and unique point.

These same requirements apply to four-corner tracking. If you're replacing the image of an old TV you may find that the TV screen is rounded and almost blends into the frame of the TV. In this case you may want to put fluorescent dots from the office supply store on the corners of the area you want to track. You'll need to paint or composite out the dots in the final scene.

If tracking points don't exist in the scene and you need them then you have to create them. If you're shooting an actor in front of a blue screen to create a distant vista in post production then place markers on or in front of the bluescreen. These may be 2 to 6 inch plus marks made out of tape or plastic. If it's a cloth screen material you can put Velcro on the back of the plastic markers. If you can't touch the screen use c-stands to hold them but note that there will be more removal work to do in post. It's important for any markers to be solidly locked down so don't suspend with them with thin wires.

You want the markers to be visible on the final film scans but not too large or you'll be doing a lot of extra paint out. Same with the number of markers. You want to always have 2 or 3 markers visible even when you pan and tilt the camera. If you plan to pan the camera 180 degrees hen you'll need a number of markers around the camera. The actors or props may obscure some of the markers. If you're doing a full day of shooting in front of the bluescreen then it's best to just setup a grid pattern of the plus marks. Note that if the depth of field makes the markers way out of focus or if there are no markers visible in the shot it becomes a matter of experimenting in post to create a move on the background that seems to work with the foreground. This can be very time consuming and frustrating especially if your actor is jumping or moving.

If you're doing 3D motion tracking you always want to have at least 3 trackers visible. As always the matchmover will be recording the lens and tilt information from the camera, possibly with the help of the coordinator and certainly with the help of the camera assistant. If you're shooting on a set the matchmover should be getting measurements of anything with straight lines that are clearly defined such as the tabletop or windows. With this information they can build a rough CG version of the set. Set drawings are seldom used to build the CG matchmove version from since there may have been adjustments and changes made to the real set that aren't reflected in the blueprints. You want to make sure to build the CG world to what's actually captured on film, not on what was planned. To help with this work the matchmover usually shoot stills and especially Polaroid's where they can mark the actual dimensions on the image. These and the notes will be used months from now when the visual effects are being started. In some cases stereo images are taken or multiple cameras are used to help document the relationship of the objects in the set.

For organic sets such as caves or outdoors in natural landscape small ball markers are typically used. It's important for these markers show up so they are usually ping-pong balls or tennis balls painted a fluorescent color. Bright LEDs can also be placed in ping-pong balls. This is especially useful in darker sets or night shoots. At times a box frame of known size is filmed in the scene as well to provide a defined object and perspective check.

If the scene is supposed to be a close-up of a creature but there is no fixed object in frame then vertical rods may be used that hold a marker in place. As always there should be at least 3 markers.

If it's a large exterior scene on uneven ground a grid of markers may be set down or at least measured. Now the animator will be able to match the creature feet directly to the real ground. On DragonHeart and most of the shows afterward when filming in a large natural setting we used a surveyors transit system connected to a powerbook or a handheld computer that records the true position in 3D space of xy and z.

The matchmover back at the studio creates a 3D ball in the computer matching those coordinates. In the past the computer camera would be moved manually to match the position. Now there are special 3D tracking programs that can do this automatically.

Face Markers
Sometimes we're required to create CG prosthetics. This is done for shots that can't be done as normal makeup work since it's going to change during the shot or it requires removal of sections of the real actor. This is the case with the jaw extensions in Van Helsing and the facial electronics in something like the latest Terminator movie. Small colored dots from an office supply store can be applied to a face or arm. It's also possible for the makeup person to apply makeup marks. In these cases it's important to know where to place the dots to get the best match. Because of muscle changes you typically want some on the cheekbones or area that won't change as much in addition to the edge of the imaginary prosthetic. The animator, model maker and/or matchmover will then have to change to shape and position of the CG prosthetic to match frame by frame.

Note that matchmoving doesn't solve the problem of repeating live action camera moves such as required for twin shots and doesn't provide us with a clean plate. It is possible to take the match move data and convert it into a move for a motion control systems later when you're shooting live action or miniature elements. If you need a clean plate (for paint restoring) then the operator tries to repeat his same movement as accurately as he can without the actors and then the compositor will have to massage it in post to try to make it work.

Low Budget
Most beginning filmmakers want to make as complex scene as possible but it's important to keep it simple and to learn the basics of the craft before overwhelming yourself.

As mentioned before the simplest process is the locked off camera. Attach you camera to a solid tripod and film your different elements, including your clean plate as needed, without touching the camera or tripod. This allows you to focus on the art of compositing without getting tied up in the difficulties of match moving.

If you're creating CG elements measure the set or area and try to create a replica of this. Use real units of measure in your computer graphics program. Measure your camera as well. This would include the height from the ground and the distance from camera. Technically you want the nodal point of the lens but middle of lens or film plane is usually accurate enough to start with.

You also want to record the tilt of the camera. You can use an inclinometer to measure this tilt. You can find these on the internet or at larger hardware stores. You don't need the fancy, all digital versions. A simple type based on a bubble level is fine. These are 3 or 6 inch vertical disks with a flat bottom. A needle always points up to provide a readout the number of degrees of tilt, Place it on something level to the film plane, such as the tripod head plate.

If you can find one of these or they're too expensive then get a simple 6 inch protractor. Tie a knot in the end of a one-foot piece of string. Thread this through the hole in the protractor from the back. Tie a weight such as a large nut or bolt to the other end. Place the protractor upside down with the straight edge of the protractor resting against the straight edge of the tripod head. Read the degrees where the string passes the protractor. You may find in your CG program that you have to add or subtract 90 degrees from this number or you may have to negate the number. There's no absolute position for pan so we don't bother to measure it.

Place your CG camera at this point and use the set you built be your guide to where to place the CG creature or object. You also want to be able to cast shadows from your creature onto this ground plane and any large objects such as tables.

Once you've done these types of shots then you can experiment with 2D motion tracking and 3D matchmoving. Start the 3D matchmoving by using just pan and tilt when shooting.

Wednesday, November 23, 2005

Comments and iTunes

Just so everyone knows, right now when you post a comment it sends me an email and then I have to approve it. So if your comment doesn't show up immediately don't worry, I'm probably just slow getting to it.

On a side note if you have problems using the original feed on iTunes you can click on the Effects Corner on iTunes link on the right.

Thanks.

Monday, November 21, 2005

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.

Sunday, November 13, 2005

Bidding and Preproduction

Visual Effects Bidding and Preproduction are covered in this podcast.
Storyboards and animatics are included in this discussion.

Transcript
Today I'll be discussing the start of the process, which includes bidding and preproduction.

A studio or producer will contact a visual effects company, which is also referred to as a visual effects house. If a producer or studio has a relationship with an effects company they may provide the script only to that company but more likely they will have at least 3 or 4 effects companies review the script. Studios often have a postproduction supervisor or even a visual effects head who is involved in making sure the postproduction process flows smoothing. If a production company is contacting the effects company directly they may have hired a visual effects producer for the film itself. This is common if the film is very large and will the work will be split out to a few effects companies.

Most of the time the producer will have a script for a film that's been greenlit or is close to being greenlit. Greenlit means that the money has been approved to make the film. Sometimes the producer just needs a ballpark estimate before it precedes any further in development.

At the effects company the visual effects supervisor and effects producer review the script. The visual effects supervisor and effects producer mimic the director and producer but specifically to visual effects. The supervisor's job is to oversee the work from both a creative and technical standpoint and make sure it accomplishes what the director needs. The visual effects producer is in charge of the budget and schedule of the work.

The script is reviewed and the supervisor and producer make notes on what they think the effects work will be. Typically I tag anything that might be effects work and create a list. Details about what the client wants may be minimal at this time. The supervisor and producer sit down and create a ballpark budget based on a rough idea of techniques and their experience. The next step is a meeting with the director and film's producer to clarify exactly what the vision is and what they think they can accomplish with stunts and practical effects work. Based on this conversation the list of effects shots is revised and a new ballpark estimate is created. It's important to provide these estimates in written form so there's no miscommunication.

Before more detailed bids can be created and the job awarded the work has to be very well defined. Scripts usually don't have a lot of detailed descriptions and even when they do the director may have other ideas.

This is the start of the preproduction phase. For a large film this can be 6 to 9 months before shooting even begins. Once filming starts there can easily be a crew of 200 or more people at a minimum cost of $100,000 or more per day. Anything that can be done in preproduction to speed up the actual shoot and make it as smooth as possible is worth it. An ounce of prevention as they say.

The concept phase
In many cases you're being asked to create something that doesn't exist so it's critical to get the design down on paper to allow communication with all involved. The production may start a concept phase where they hire an effects company or their own artists to create artwork. The visual effects art director plays a key role here. The director may not have a clear idea of what the creature or gadget or vehicles is supposed to look like so numerous sketches are done by the artists. The first step usually covers a wide range of possible looks and the artists may also work closely with the production designer to make sure they're on the same page. If there are elaborate makeup or costume designs these are proceeding as well and in many cases the teams work together. Hopefully the director will be clear about which parts of which designs he likes and the designs are refined further. In end color concepts are usually created and in some cases a model sculpture is created. This is sometimes called a Marquette.

Directors vary a lot in terms of being able to visualize and communicate their ideas. It some cases the director may not know what he wants until he sees it. This means you could spend a lot of times doing concept art and in some case this may continue on well into production which can cause further complications.

Sometimes during this concept phase I may shoot some video and do some moving mockups to try to clarify what the effect might look like in motion.

Storyboarding
The next step is to storyboard all the visual effects sequences. There needs to be one storyboard or sketch of every shot that will have effects work. If it's a complex shot with a lot of movement or action then multiple panels will be done similar to a comic book except the format for all shots is the format of the film frame. The production may hire an artist to work directly with the artist or they may have the visual effects company artist work with the director. It's important for the visual effects team to be involved in the storyboarding since they have the most experience in what works and doesn't work in this area. I always suggest to a director he storyboard the shots as if it all existed. This avoids the effect shots being approached differently than the live action and avoids dwelling on a single effect.

Storyboard may seem to suppress the creatively of the scene but they're very important for a few reasons.

A single shot may require a number of departments to work together and prepare for the filming of the shots. With storyboards and concept art the director is able to easily communicate to everyone. A picture as they say is worth a thousand words. Without the boards each person would envision the shots differently.

For the visual effects crew we can't budget a shot until we see what the director sees. It's one thing in the script to set the action as a dogfight in space but it's critical to know the exact number of shots. The effects supervisor has to analyze every board and determine the technical process to create the final image. If an actor is framed one way that might require a bluescreen but if the shot is framed another way it may require rotoscoping or may be a simple split. A single shot may require a dozen different images or as we call the elements. There may need to be a section of a matte painting, a shot of the main actors on location, a shot of some extras against a blue screen, a model shot with motion control and a computer graphic creature all in one shot. Some of these elements may be shot or created over a span of a year so planning is critical. In a film such as star wars there about 2000 shots. Most shots average 5-8 seconds in length for budgeting purposes. In the old days. And I use the term old days to reference pre-digital effects; a large show was 200 shots.

Animatics
If a sequence is very complex, production may want to do animatics. These are essentially moving storyboards. They may be as simple as editing the storyboards together to check the flow and timings of the shots or may involve elaborate 3D models with animation. The storyboards do a good job of conveying the composition and basic action of the scene but moving images provide timing information and camera motion. At times we may videotape models by hand or do other types of mockups using clips from other references.

Both storyboards and animatics are used as a guide and starting point with the understanding that some of the shots will need to change when shooting based on the locations and the actors. It's important not to get too hung up on animatics. Because of their simple texturing they usually don't do a good job of conveying the sense of speed compared to a live action image projected onto a movie screen. It also becomes very easy to create shots you can't actually shoot due to the camera speed or other real world limitations. Some directors try to finesse the animatics in great detail which can make it that much more frustrating to them. They should be used just enough to convey the concept of the shot.

Once the boards are created then it's possible to create an accurate budget for the visual effects work. Budgeting is one of the most difficult tasks in effects work since there are still quite a few unknowns I usually gather the heads of the different departments and review the storyboards. Each department head provides their estimate for the amount of time they expect a shot to take for their discipline. Animation, matte painting, compositing, technical director, etc. Ideally they will bid it based on the performance of their average worker. It's easy to become optimistic when bidding about how quickly the work should be done and how the shots will all flow as planned. Reality and experience quickly temper this urge. Likewise if someone has had a bad experience they may pad their estimates. In either case these deviations from the target add up since there may be several hundred shots budgeted this way.

When reviewing the techniques to use it usually isn't a question of how to do an effect but which way is best for this particular film. Each technique has certain limits associated with it. I'll cover the details to this in another podcast.


As mentioned before it's also common for the studio to bid out the project to multiple effects houses so budget is always an issue. On larger shows the studio may end up dividing up the work among a few effects houses. When this is the case the film usually has an effects producer or coordinator assigned to it to oversee the project to make sure budgets and schedules from multiple effects houses are on target.

Most productions are done on a fixed bid that means that any overages are out of the effects company pocket unless the director requests changes or additions to the from the original planned shots. Part of the budgeting process is determining how much coverage is included for changes. Some places bid a bare minimum, which requires them to request, a change order from the production for additional charges even when a minor change has taken place. Most of the larger effects houses try to include enough funds to cover typical adjustment requests by the director.

The time is also a consideration when budgeting. If there isn't sufficient pre-production or postproduction time the crew may have to work overtime. In this business a 50-hour week is usually a minimum. Days are usually 10 to 12 hours long and a workweek can stretch to be 6 or even 7 days, especially toward the final completion of the project. At the end of Star Trek the motion Picture I worked 90, 12-hour days straight. Since the movie release date is locked at the moment it is greenlit it becomes an unchanging deadline. Obviously this will affect the budget.


You may have to do a fair bit of research and development to create the look the director is after and since this is an artistic endeavor with a different director on each project the amount of time it takes will sometimes be an unknown. One director may like the look of the shots very easily and another may dwell on some detail in a single shot at the expense of other shots.

During the pre-production phase the film departments are busy creating the sets, costumes and other items required for the shoot. On the visual effects side the R&D, research and development, is in process and tests are being shot if new techniques are required. Some of the models (both CG and physical models) can be constructed. Just a note here that CG refers to computer graphics. Visual effects artists usually use CG instead of CGI since it's shorter and not redundant.

We also use this time to work with the director of photography to make sure we're in sync with them. The film stock and shooting process will discussed since this could affect some of the approaches taken in post production.

As the date for shooting nears the visual effects supervisor goes on the tech scout with the other department heads. This may be reviewing the sets or flying to the locations where the film will be shot. The effects supervisor works closely with the director of photography, the practical effects supervisor and the stunt supervisor. Some revisions to budget and storyboards may need to be done once the tech scout is done.

Preproduction on your own
Even if you're doing the visual effects for your own miniDV movie it's important to take advantage of preproduction. It's best if you do a simple sketch or storyboard of your shots. This doesn't have to be anything fancy, it's just to help you review what you're planning to do. When you've sketched it out it's easy to spot some potential problems you might not have thought about.

You'll have to figure out what techniques will be required for each shot. If you haven't done much of this before it's best to keep it simple because a simple shot well done is better than a complex shot poorly done. In most cases a locked off camera will make the shot easier to do. This means use the camera on a tripod and don't move it.

Also consider doing what the professionals do during pre-production. Test. If you have a video camera then try to shoot a simple version of your shot with people filling in for the actors. Step through the process of the shot with this test footage so you're clear about how the technique works. You don't need to finish the shot but this can help figure out how to best shoot the images and how much work will be required in post production. It may not cost you in money but it's important to understand the amount of time required. By doing a test you'll also gain a bit more experience so that your skills will be better for the actual shots.

Well that wraps up today's podcast. Shooting the visual effects will be our next topic. Thank you.

Related post
Budgeting VFX

Friday, November 11, 2005

Update

Hoping to get the next podcast uploaded tomorrow.

I've started listing this site on various podcast directories. iTunes kicked it back for some reason and their system seems to be broken so I've been unable to resubmit it. Those of you with iTunes will have to manually add the feed for now. Sorry.

As mentioned post comments, suggestions or questions here or send me email to effectsNOSPAMcorner@mac.com (remove NOSPAM when sending)

I'm considering posting the transcripts of the podcasts here if people are interested.

Sunday, November 06, 2005

Intro to the Effects Corner Podcast

I've posted the first podcast for the Effects Corner. This is a very basic introduction.

Copy the link to the right into iTunes subscribe to Podcast or click on link of this post name.

Suburban Legends

Last Staturday I saw Suburban Legends perform in Oakland for iMusicast. If you ever get a chance to go to a concert of their's - go! In addition to the great music it is an amazing, energetic and entertaining show. The amount of life this group provides on stage inredible.
This makes the death of one of their members, Ryan Dallas Cook, from a hit and run driver the week before, all the more tragic.
Update on Hit and Run criminal