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pag3833
02-16-2010, 12:19 AM
Hello guys.

I'm trying to achieve a shot for a project I'm working on that basically is someone spraying graffiti onto a train. obviously I can't achieve this shot with live action as its dangerous and against the law so I was wondering, in your opinion, how would you go about creating this shot? it needs to look as realistic as possible.

I could get footage of a train in a station and then....
I thought green screen... (with a mock version of a section of train) but shadows would become an issue? and how well would this transfer onto train footage with tracking
rotoscoping... how could i roto the spray paint on the surface well enough?
I could go the 3D route....?

I'd just like other peoples opinions on what you'd do if you were given this task?

Thanks for your time

Pag

suztv
02-16-2010, 02:54 PM
Greenscreen could work - as long as the paints used aren't green (obviously) and you have several sheets/walls of green to paint on. Also you would have to get the angle of the train station wall and camera distance etc. and match your green screen set up to that.

Lighting might be another issue since spill and the lighting of the screen may cause some artifacts or problem areas. It's worth a try though.

pag3833
02-16-2010, 04:59 PM
yeah i thought green screen would be the best option. but the problems i think i'd face would be if it was painted directly onto a green version 'train' matching the original footage, then there would be alot of shadow issues. possibly could use a clear screen infront of a greenscreen but i think light reflections etc would be an issue then.

ill do a few test samples... see what results i get

if anyone else has any other good ideas i'd very much appreciate the input


cheers

Khalor
02-17-2010, 03:55 AM
You could create the graffiti in Photoshop (or by spraying onto black or green card, then photographing it), then track/pin it on to the side of the train in post... have your actor mime the appropriate spraying motions with the can, and roto the photoshop graffiti plate to reveal as the can moves.

Things to consider:
- the 'sheen' of the paint changes as it dries (which happens fairly quickly), you'll need to replicate this in your composite, possibly with 2 versions of your graffiti plate timed differently.
- the spray from the can will need to be comped in - something you could possibly do with particles or (depending on the camera motion) by shooting against black or green and comping in.

There's probably more gotchas to consider, it's best to look at real-life reference (get a sheet of metal or whatever and spray some grafitti on, video it, watch it and make notes) when tackling anything like this.

Or you could get permission to put a sheet of gladwrap over a stationary train and spray on to that.

pag3833
02-20-2010, 12:36 PM
thanks guys. ill do some test samples and see what results I get. I think the photoshop route will be very difficult tho to get a realistic shot but we'll see what happens...

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