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Simulated Day Exterior Car Travel

Published : 8th January 2007

I have an up-coming short film involving two characters and dialogue inside a moving car interior during the middle of the day. A low loader is out of the question due to budget.

Has anyone shot 'sim-travel' using projection or green screen in a studio for day time? I have shot night time 'sim-travel' in a studio successfully, but never tried it for day time.

How is this done successfully for photo realism? Are there any good examples any of you can offer up? Thank you all in advance for any advice/experience.

Cheers,

Dan Freene
Sydney DOP


Hey Dan,

You might want to check out Andrew Kramer's After Effects Training DVD http://www.videocopilot.net/seriousfx.html as he covers this topic. There's not really any detail as to the shooting side of things, but you can see what he's done in the footage, and it gives you an idea of what to shoot for when you know what you'll have to do in post.

I'm not affiliated with Mr Kramer or VideoCoPilot.net in anyway, but there's some pretty useful stuff on there!

Jamie Fraser
Creative Director
Feed Media Stuff, Bath, UK
+44 (0) 1225 344 080
+44 (0) 7764 497 638


Dan Freene wrote:

class="style15">>>I have an up-coming short film involving two characters and dialogue >>inside a moving car interior during the middle of the day.

I've done process shots (projections) only for night time in car shooting, but did a daytime shot in a city bus. We just put light grid cloth on all the windows and blew them out slightly. The most effective thing to carry the illusion is to rock the vehicle slightly so it appears to be moving, which we did.

Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Greenville, SC 29614


Hello Dan,

If you're not concerned about actors who are delivering lines driving.... I've put ND9 on the windows behind the actors (generally on all the windows except the front windshield). On the front windshield (wind screen) leave a LARGE viewing area for the driver to see what's on the road. On the passenger side, put some light grid or diffusion of your choice. You can also tow the car (a much safer solution). Be sure to wrap the chains with cloth or something to dampen the sound of metal on metal. Use common sense in driving on the road. It's only a movie and not worth getting hurt.

Mark Woods
Director of Photography
www.markwoods.com
Pasadena, California


We did a test on this a few years ago.
I had shot background plates on both 35mm & HD.

The footage was transferred to DigiBeta. We had a nice high end DLP projector and rear projected this material onto a rear-projections screen and built this around the car on a stage.

It looked great!

Since we were shooting 35mm for the dialogue, the projection, even though it was sharp, looked realistically soft focus due to the 35mm depth of field. Once, on a slightly wider 2-shot, we had to soft focus the projector... The HD originated projection [again, down converted to d-beta] looked just as good... The only slight snag we had was the projector's bulb was daylight balanced. The video tech we had could not warm it up enough to our tungsten studio lamps...so I did an easy fix by taping on a series 9 85 filter to the projector!

Perfect!

In hind sight, I only wish that we had mounted the car on some type of turntable....when we switched sides from the driver's to the passenger's, we had to roll the entire rear-projections system [projector & screen] around the stage or try to drive the car around, which was very difficult.
But, it really worked far better than I had thought and the footage was very believable.

Make sure you do the little 'sell' trucks like having your key light mounted onto a dolly so you can slightly boom it up & down and have it travel a little back & forth...as well as flying branches across the front to give the illusion of passing trees & telephone poles, etc...

A little blue skylight fill works great!

Make sure the windshield does not have too much of a green band on it's top.

Cheers,
Jeff Barklage, s.o.c.
US based DP
www.barklage.com


Mark Woods wrote:

class="style15">>... You can also tow the car (a much safer solution). Be sure to wrap the >chains with cloth or something to dampen the sound of metal on metal. >Use common sense in driving on the road. It's only a movie and not >worth getting hurt."

Towing with chains (or rope) is not legal in some areas. Use a tow bar.

Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Greenville, SC 29614


class="style15">>>Be sure to wrap the chains with cloth or something to dampen the >>sound of metal on metal. Use common sense in driving on the road.

Safety chains on the tow bars. Using just ropes or chains is clearly not using "common sense."

Mark Woods
Director of Photography
www.markwoods.com
Pasadena, California


And I found there are two types of tow bars, one that keeps the front end much lower than the other. Be specific when ordering these, so your car isn't at a steep angle. It's a very slow process, working on a moving vehicle. ND gels are useful.

If you go with Jeff Bark lage’s studio solution (great run-down, Jeff!), I can say that instead of a turntable, they make little devices that go under each of the car's wheels and lift the car slightly so it's on large casters, and you can just push the car any way you want on a stage floor. I believe you can rent them, but I think I've seen them at Pep Boys.

Talk to your transport dept.

Best wishes,
Graham Futerfas
Los Angeles DP
www.GFuterfas.com


Graham Futerfas wrote:

>>And I found there are two types of tow bars, one that keeps the front >>end much lower than the other. Be specific when ordering these, so >>your car isn't at a steep angle.

One's called a Tow Bar, and the other is called a Tow Dolly. Due to energy absorbing bumpers, etc., very few contemporary vehicles can be fitted with a tow bar. Car shots with tow bars, usually means that the car is rigged with tow tabs; these are pieces of steel welded or bolted to the frame of the vehicle and require a custom made or modified tow bar.

The tow dollies that are available for rent at U-Haul, etc. are designed to transport a passenger car over the public roads at highway speeds. They are not designed for car shooting, as noted they are too high and tilt the car at an unnatural angle.

Nearly all camera car operators have custom built tow dollies that are designed for minimum ground clearance, and with smaller diameter wheels and tires, so the towed vehicle will appear to be at the correct or normal vehicle height and will be level.

If you use a rental tow bar, you can remove the wheels from the picture car and replace the stock wheels with smaller wheels and tires, or just rims or just the front spindles -- whatever it takes to get the picture car at the height required.

class="style15">> It's a very slow process, working on a moving vehicle.

It can be, but that's why camera cars and tow dollies and process trailers were invented

class="style15">>> If you go with Jeff Bark lage’s studio solution (great run-down, Jeff!), I >>can say that instead of a turntable, they make little devices that go >>under each of the car's wheels and lift the car slightly so it's on large >>casters

They're called Go-Jacks, and there are other low budget substitutes available from places like JC Whitney, etc. Ordinary wooden furniture dollies will also work -- if the car's not too heavy, but you'll need to jack up each wheel, one at a time. Go-Jacks have wheel jacks built in, hence the name.

BTW, they are not particularly quiet on a concrete floor.

Brian Heller
IA 600 DP


Graham Futerfas wrote:

class="style15">>>I can say that instead of a turntable, they make little devices that go >>under each of the car's wheels and lift the car slightly so it's on large >>casters, and you can just push the car any way you want on a stage >>floor

These are what guys in NYC parking lots use to move cars after the owners leave with the keys. Any disreputable towing company can point you in the right direction, or just get the northern tools .com catalogue and peruse....

Mark Smith
DP nyc


Thank you all for your responses thus far.

After reading and further discussion with the director/producer, I am leaning towards the rear projection technique Jeff suggested.

As far as getting the moving car bumps, what seems to best the best setup? A couple of people bouncing the vehicle???

I figure the camera will be mounted to the bonnet of the vehicle, so the camera will ride the car bumps. OR, is it best for the camera to remain solid and just let the car bounce and bump?

Dan Freene
Director of Photography
Advertising Advantage


Both rear projection and green screen methods have been used for daylight driving scenes for years...RP for longer, obviously.

At the risk of stating the obvious (something for which I am well known, if not famous) there are a few things that give away poorly done process work pretty quickly...if you avoid doing the wrong things, what 's left will probably work.

Things that give it away :

1/. Focal length: If your background has been shot on a different focal length than your foreground, it will probably look wrong. Let me amend that...the angle of view of your foreground taking lens should match the angle of view of that portion of the background plate that you are viewing we often shoot backgrounds wider than the taking camera on stage, but we don't look at the whole width of the background image at once in that case.

2/. Depth of focus and focal plane :

Nothing says FAKE louder than a foreground actor in focus, an out of focus rear deck of a car, followed by a totally in - focus background rushing by.

Most post houses will ask you to shoot your background plates in focus, not focused as you would be for the actual shot. Whether 'tis better to bake the soft focus into the background plate by shooting it that way or whether 'tis better to shoot the backgrounds sharp and let the post folk fuzz it up later (in the case of greenscreen or bluescreen, that is) is a matter of some debate...but if you decide to shoot your background plates sharp, then at least shoot a reference of a bit of running footage at the sort of f/stop that you would be shooting the foreground car stuff with the focus set at what it would be set at if shooting in the car, so the compositor has a focus reference (and you have limited your liability by showing them what it SHOULD look like.)

3/. Foreground lighting not matching the plate :

This is more or less of an issue depending on the type of plates and, of course the type of vehicle...convertibles and motorcycles are much less forgiving than tinted-window limo's.

Get the predominant key angles right, at least...even if those lights hit the various bits of car interior and don't hit the actors...obviously, you are better off shooting the background plates first, because then you can match the lighting to them.

4/. RP can work really well, but takes a bit more care, in some ways, because you need to light your car while keeping as much spill as possible off the screen. One advantage is that any reflections from the rp screen onto the car actually work, whereas greenscreen spill onto the car is spill and either has to be minimized with clever grip-work or at the very least, some sort of moving reflected image needs to be comped into the spill portions (as they would be there in real life.)

Working with blue or greenscreen, you can put the screen back a ways - you don't have to worry about depth of field... with RP, you have to think about how far back you want to put the screen...if it is too far back, the background might be too soft for a daylight scene...

there are a lot of variables to consider and a bit of homework to do, but either RP (digital or film) or blue or greenscreen can be used to do very naturalistic driving stuff.

If you go the RP route, you want to work with a pin-registered projector if at all possible, like, for instance, the HansardVision Hansard projectors. Digital projectors are pretty damned stable, of course.

One of the advantages of RP is that at the end of the day, the work is done - the composites have been done in camera. The disadvantage is that at the end of the day, the work is done - the composites have been done in camera.

General notes :

Unless it is a broad physical comedy, avoid excessive wheel movement on the part of the actor/driver... ever since the advent of power steering, actors have been turning wheels farther and harder than they would in real life.


Likewise, modern cars have pretty decent suspensions...don't over-bounce the car to sell the movement...but, of course, do have some movement to the car...you can spend millions on fancy computerised systems, but at the end of the day, you always end up with a "grip on a stick" ...that is to say a 2x4 or 2 2x4's screwed together resting on an applebox and fetching up under the bumper of the car (out of frame, of course) with a grip randomly adding jolts and jiggles to the car. A good grip is better than a great computer, in my mind...though most of the grips I have worked with wouldn't believe that it was me saying it

Do your homework. figure out what lens focal lengths will cover your scene and what camera angles (tilts and pans) BEFORE you go out to shoot your plates. You can probably shoot your background plates out of the sides and back of a minivan...most of which have more compliant suspensions than most insert cars.

Buy Zoran Perisic's book "Visual Effects Cinematography".
No one describes the issues better than he... Anything Bill Hansard Sr. has written on the subject is equally weighty in value.

You should also read the relevant chapters in the various ASC manuals...I am away from home so I can't say which editions should be perused...but they will explain different frame rates (or driving speeds) at different pan angles ( I think, off-hand, that if you are shooting across the car (90 degrees to direction of travel) you run your plate vehicle at 40 percent of your actual speed...) I've been shooting these things for years, but I always look everything up instead of trusting what is left of my memory)

If you go RP, realize that most projection systems (digital or film-based) are daylight balanced, not tungsten.

Either correct the projector down to tungsten with an 85 or use HMI's or other blue light sources on your car set...I have done both - they both work fine.

If you go film-based RP, however, you cannot just make a warm print and expect it to solve all your colour balance problems...

very bright objects in frame (anything white that will have a very thin bit of print, for instance) will come out the colour of your projector bulb...only darker objects will be appropriately warmed in the print.

Somewhat different in the digital projection world, but even so, I would use filtration rather than try to get the projector to balance tungsten when it really doesn't want to.

Good luck, and go for it, by all means... the alternative of having actors trying to drive with hard-mounted cameras and lights all around them can be rather dangerous at best...worth doing sometimes, but not always.

Very few people have gotten into car accidents on process stages, though I know a few who have.

Mark H. Weingartner
VFX Photography & Supervision
LA based


class="style15">>>After reading and further discussion with the director/producer, I am >>leaning towards the rear projection technique

Good choice.

class="style15">>>Jeff suggested. As far as getting the moving car bumps, what seems >>to best the best setup? A couple of people bouncing the vehicle???

Rig a 12-16 foot long 2"x4" as a "see-saw" lever, one end under the bumper and with a fulcrum about a foot high - one in front and one in the rear. Then one person on each lever can easily bump the car at random intervals.

class="style15">>>I figure the camera will be mounted to the bonnet of the vehicle, so the >>camera will ride the car bumps. OR, is it best for the camera to remain >>solid and just let the car bounce and bump?

I think the camera independent of the car looks better. Mount the camera on a dolly or tripod in front of the car, have the operator give some minimal pan & tilt movement while the car is bouncing and the rear projection plate is also moving. Dollying side to side slightly also helps. The combination movement looks really good.

Don't forget to try to synchronize "turns" in the projection plate with the actor turning the steering wheel - a dead giveaway if the timing is off.
Lights on dimmers and waving nets and flags in front of the lights at random intervals completes the illusion.

For "Stardust Memories" (35mm black & white), we did a lot of RP "Poor Man's Process" for the interior Rolls Royce shooting, both day and night. We shot plates straight back, at 90 degrees (both directions), and at 45 degrees (both directions), for different shooting angles on our actors in the car.

Shoot plates in long uninterrupted takes (longer than the RP shooting you want to do, so you don't run out of plate before you finish the dialogue), and shooting a 15-20 second grey card at the head of each plate gave us a good indication of exposure consistency when the plate was projected. We just read the projected grey card with a spot meter and balanced the car interior lighting accordingly.

Good Luck!

Doug Hart
1AC, NYC


I figure the camera will be mounted to the bonnet of the vehicle, so the camera will ride the car bumps. OR, is it best for the camera to remain solid and just let the car bounce and bump?

Generally, locking the camera to the car's frame of reference is most likely the visual vocabulary that we are familiar with in film-making... it depends, of course on what you are trying to say, but I would start with that sort of rig, using the "bounce and bump" primarily to jostle the inhabitants of the car as well as jostling the horizon around in the windows as it would do in real life.

See my other notes on an earlier post regarding car movement don't overdo it.

Mark Weingartner
LA based


 


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