Green Screen on location?

[Storyteller]

I'd be glad if anyone could give me a bit of advice about using a green screen on a location, especially if they've done something similar.

The situation I have is that in my new film, my protagonist has to throw himself in front of a train in an attempt at suicide (which fails!!) I've made contact with a small local preserved railway, who are happy to help out, but there's a snag.

The original station building and waiting room stands on the old main platform, and this has the right look for people to be standing around, waiting for a train. The little difficulty is that there's no track beside this platform. I can have my man throw himself off the platform (and not film his landing, hopefully on something soft).

On the other side of the old goods yard is the 'cattle-loading platform', which does have a track, so I can film the train approaching the platform there, and even have my man laid across the track (the train stops short, or should do!! )

My question is, is there a way of using a green screen where the track used to be, by the old main platform, and then editing in the approaching train? And what's the best way of suspending it 'invisibly' (It's a 2.5x3m piece of cloth, intended to be suspended from a pole, but the stands for the pole would be kind of obvious.)

Close-ups of the moving train will be possible, on the cattle-platform track.

Has anyone tried anything like this, and are there any stumbling blocks I have to look out for? (I was thinking about whether the distance from camera to green screen has to be the same as camera to train, but I don't know.)

[Chrisbitz]

Have you considered not using the green screen, as it adds tons of complexity, and trying the old split screen trick where the train and the person are filmed at different times, and merged with a split screen.

it's a very simple effect, and very effective too...

http://www.coulsonmedia.co.uk/DanRob.wmv

Would that fit your story at all?

In my experience, as well, unless you're doing closeups only, a 2.5x3m green screen will become very small if it's any kind of distance from the camera too..

Another thing to consider, is if there's any wind at all, imagine the fun of holding a 3m sail taught and smooth!

[Mike Shaw]

I would definitely suggest doing the same thing - forget the green screen approach for such a 'trick' in the open.

Virtually all editors can do a 'simple horizontal or vertical split screen (soften the edge very slightly, and pick a 'natural line' a platform edge or wall edge for example for the dividing line): you can also use a mask if the editor allows such things - if it does, chances are you'll also be able to 'track' the mask for a more dynamic shot.

These effects need careful planning before the shoot (watch the light sources!), and careful compositing in post, but you will have a far better result than using green screen.

Good luck!

[Dave Watterson]

As has been pointed out, there are other ways to do your scene ...

But remember that there is nothing magical about "green screen material". ANY background of a single colour can be used and replaced in the edit using chromakey techniques. While rough-and-ready backgrounds may not be evenly enough lit for perfect results any faults will be less visible with an action sequence. I've seen acceptable results from tarpaulins ...

However, please do reassure us that the critical scene will be shot with the body and stopped train together, then the train backing away from it. You reverse the shot in the edit. Actors are not expendable! Of course you need some good shots of the train racing towards camera too and you cut to the reversed shot only for the last moment.

I recall seeing a scene being made for television where a train and car collide on a level-crossing. The "train" was a huge hardboard cut-out, shaped and painted like a locomotive, fixed to the side of a small van which drove on planks laid on a section of disused track. That allowed a great deal of control with minimum risk. Can you try a variation on that trick?

- Dave

[Mike Shaw]

I think I must have a quiet word with you sometime about 'special effects' in post production Dave!

In fact it isn't necessary to have train and actor on the track at the same time at all - let alone have the train run backwards - or even shoot the two on the same day (though for lighting reasons, it is a good idea to do so if possible).

I remember years ago after seeing my Remote Control one dear old lady commented - "You have some lovely coloured shirts - very clever the way you kept changing them...".

A good 90% (I reckon) of the effects - special and otherwise - seen in movies are created in post. Especially when you see people swanning around the world in a film: they don't always use green screen by any means - or even build special sets these days. Mattes (masks) and motion tracking are the big secret behind most of them.

We had a talk at our club from the special effects team on the failed BBC Sci Fi programme Outcasts: apart from the actors, virtually everything (everything!) else was created using computer graphics. One scene for example showed the young couple on a hillside, at night, on an alien planet landscape, looking down on the twinkling lights of the nearby shanty town, with two moons in the sky. It was shot in broad daylight - on a sunny day to boot - in a flat field somewhere in the home counties. Everything - including the colour of the girls hair, if I remember correctly, was transformed in post production using very sophisticated computer graphics.

With careful compositing, a scene created in post production can look far more convincing than the same scene created 'artificially' on set with props and so on, and it is - or can be - a lot cheaper doing it in post.

They used to say the camera doesn't lie. That may be true still, up to a point. Or, they may have lied. Either way, just don't believe what you see is what the camera saw, or what actually happened!

[Storyteller]

Thanks all for this advice, much of which was new to me.

Hadn't thought of starting with the body on the track in front of the train, the latter stationary, then having the train back away, only to reverse direction of the shot in post. Had to look through the extremely large (1000+ page) manual which comes with Edius 6 to find it could indeed do this. I expect my leading man will be pleased. <g>

I didn't find anything labelled 'split screen' in the manual, but from looking at the section on masks, it's obvious I could create one. I'm thinking I would need to shoot (I'll be using a crane to get above the train) along the line of the edge of the platform, on both platforms, then combine the shots, masking out the unwanted half of each image.

Whatever, both these make the green screen unnecessary - the problems that might be caused by the wind hadn't escaped my notice. <g>

I shall learn, later this month, whether this all works!!!

Once again, thank you all.

Peter

[Mike Shaw]

Any editor that has more than one video track - which is virtually all of them these days - can do a 'simple' split screen.

Place one clip on the lower video track. Place the other clip on the track above it. Then simply adjust the border on the upper track (if using a Pinnacle Studio, its the other way round - the overlay is underneath!) so that the required lower track shows through.

If using this technique - a 'locked off' camera is often essential: that is, shoot the first scene - using a remote control to start and stop the camera. Then without moving the camera at all - or even touching it, set up and shoot the overlay, again using the remore control to start and stop the camera. It should then be possible to match the two images, one as a border adjusted overlay. In many editors, this would mean the adjusted 'edge' must be paralell to the sides of the screen and that would have to be taken into account when shooting. I'm sure Edius can handle masks of any shape though.

If you can get the train driver to 'reverse' down the track then that would obviously save a lot of masking work in post. I hadn't considered such co-operative drivers! Sorry Dave! (I don't know Edius at all, but look for something like 'timewarp' - reverse motion is usually associated with that, as one of the properties). I think for safety though, I'd still be tempted to use a split screen technique.

[Storyteller]

Thanks, Mike. I do have Pinnacle Studio 15 HD Ultimate as well as Edius, so could use it if it seemed preferable. Edius is a bit like a complicated puzzle, and intriguing: it's pro s/w that I'd like to master, just for my own satisfaction - I suppose, like those people who derive pleasure from solving The Times crossword, of which I am not one.

I was put off PS when the 'video editor', which I'd become accustomed to use, suddenly began to jitter - it was virtually unusable. I think now that the problem was caused as a result of some 'disagreement' between the software and hardware - specifically my Hansol H950 digital monitor (DVI connected). For various reasons, I had to swap to the VGA/analogue connection, and discovered - lo! and behold! - that the jitters had gone away. I've now bought a new monitor, which connects via HDMI to the PC and - I've just checked - there's no return of the 'jitters' - so I am a happy bunny this morning. (The monitor is an LG E2260V-PN, widescreen LCD HDMI monitor from Amazon, under £130, and fantastic for watching Blu-ray movies, home-made or commercial. End of ad-break!!)

Peter

[Mike Shaw]

PStudio is a very capable editor and will do most things - if a little 'crudely - but in all honesty, it would be well worth your while learning to use Edius which is far superior. As a prosumer programme it probably incorporates more features and functions that you will ever need or want to use. Never mind about that - learn to do just the things you want to do as a start point - even though probably much less 'automatic' than Studio - and then add things as you need them.

The 'automatic-ness' of Studio makes it great for those who want to turn holiday movies into something more watchable, for example. A bit like using a camera set to 'automatic' for everything - focus, exposure and so on. But when you want to start creating moods and atmosphere in the movies, there is a need to move away from the automatic settings and start exploring, to get the images you want. Studio is rife with 'templates' - for transitions, filters, titles and so on -that people use 'as is' simply because there are very few adjustments that can be made to them. Calling them 'presets' also indicates they're really meant to be used 'as is' rather than tailored to suit the situation.

Once you have the rudiments of Edius under your belt, you will I am sure prefer it to Studio for everything except a 'very quick knock-out' job. I speak from experience in this - not using Edius, but Media Composer - about 3 or 4 times the price, and 20 times more complicated. It has taken me a year of struggling to do even simple things that in Avid Liquid (my other, now no-longer-supported editor) would be straightforward and quick. Now, though, thoughts of using Liquid for anything at all are rapidly dwindling away.

There are lots of (free) Video Tutorials out there for Edius (I'm told) - well worth watching those. You'll get the hang of it and pick it up much quicker than you think. And its all a lot simpler than the Times crossword, I assure you!

[Chrisbitz]

I would be very wary of using the train in reverse trick. Without getting too technical , the acceleration graph (if you can imagine it) of a train stopping suddenly, is very different to a train starting off, and I would expect it to be very noticeable to a viewer and distract and spoil the effect...
Usually they won't know what specifically is wrong, but it'll look wrong either way.

Instead of split screen, maybe have a search for "Garbage Matte", or "4 point matte" you - might find what you're looking for under that heading..?

[Dave Watterson]

In Edius right-click on a clip in the timeline.
From the menu which appears, choose "Time Effect"
From its sub-menu choose Speed
lo-and-behold in the dialog box are options for "forward" or "backward".

Have fun.

Now tell us more about this crane ...

[John C]

Has anyone tried filming one of the very old good model trains and then "Picture in Picture" the Victim?. There was a very good green screen exposition on You Tube showing this type of action. Just search "Green Screen"

I purchased a role of Poster paper 10 metre for £3.72 and it worked very well as a Green screen.

Please put your shots into Film Forum I would like to see how this turns out.

KR JohnC

[Storyteller]

Now tell us more about this crane ...

Thanks for the advice, one and all.

The crane I imported from South Carolina, Bargain-Camera Inc - see http://www.bargain-camera.com/store/Camera-Cranes-Jibs/

It came with a heavy-duty tripod stand, and three four-foot sections, permitting either 8' or 12' plus the 2' either side of the fulcrum. I knackered myself visiting the local sports shop to buy counterweights. Being prone to 'senior moments' these days, I forgot that if one buys 25kgs' worth of assorted weights, they weigh 25kg as you stagger back to the car.

One thing, the crane is fine, but as supplied it only permits the camera to tilt. Panning has to done by swinging the crane. However, the same company supplies remote pan-and-tilt heads so your camera can have that much more functionality when towering several yards above you (or hanging over the cliff edge, etc), though I'm still debating whether to push the boat out for one. They're not cheap, and remember there is VAT and probably some Customs Duty payable on imports from the USA. At the same time as the crane I ordered a 7" monitor which is battery-powered and can be attached to the fulcrum, given the appropriate fitting to hold it, so that one can see what the camera's seeing from a comfortable distance, without having to resort to binoculars aimed at the LCD screen.

Peter

[Storyteller]

In Edius right-click on a clip in the timeline.
From the menu which appears, choose "Time Effect"
From its sub-menu choose Speed
lo-and-behold in the dialog box are options for "forward" or "backward".

Dave, are you conversant with Edius? If so I wonder if you can tell me what I'm doing wrong that it seems suddenly impossible to insert a dissolve transition between a couple of clips, although it was possible between other clips earlier in the timeline?

Peter

[Mike Shaw]

I don't know Edius at all, but I'd hazard a guess based on other editors - and that is, there is no 'leeway' on the clips. Leeway is extra footage at the ends of the clips at the junction point. Without that 'extra' footage there's nothing for the transition to 'transition' to, if you follow my gyst.

So, assuming that is the case - as a guess - trim the clips back by at least the required lengfth of the transition.

If that isn't the case, then like I said ... I don't know Edius!