blue / green screen tutorial

cameronfletcher

Is there a blue / green screen tutorial or thread that some one can point me to? I want to add CGI on the background of actors infront of a blue / green screen.

Cameron.

IRML

what software are you using?

cameronfletcher

Lightwave 3D and 3D max

Chris2005

Well, you're going to need an post production tool, like After Effects to key out the green/blue screen... and then you'll need to do some motion tracking...

IRML

chris where you live in warez land it might be as simple as saying you need after effects, but some people have to make do with the software they have, it has always been possible to do compositing in lightwave, but with the node editor it is even more flexible

I can't speak for max, but in lightwave I would probably texture the footage onto a plane (there is a calculation you can do to make the plane fit the camera exactly, but I can't remember it), then use color to scalar nodes to split up the rgb channels, and a gradient node to key out the specific ranges in each channel, then combine again

evil_genius_180

I'd definitely suggest getting some video editing software to remove the green screen, it will make life easier. If you're simply wanting to remove the green screen, there is a lot of software that's a lot cheaper than After Effects. (though, I can't suggest anything, I don't green screen) There might even be some open source programs or freeware that will do the trick. I'd suggest something like that. I don't have anything against After Effects, it's just too expensive, unless that's not an issue for you.

Chris2005

IRML wrote: »

chris where you live in warez land it might be as simple as saying you need after effects, but some people have to make do with the software they have, it has always been possible to do compositing in lightwave, but with the node editor it is even more flexible

Ummmm, I said it because that's the only post production effects tool that I know of off hand...

Toa_Kaita

What about Nuke?

And if that doesnt fit your budget, try one of these: http://www.3alternatives.com/3-free-alternatives-effects

NBTrekie

chris where you live in warez land it might be as simple as saying you need after effects, but some people have to make do with the software they have, it has always been possible to do compositing in lightwave, but with the node editor it is even more flexible

Then there's always the 30day trial version of after effects...what might get the job done too....

Melak

Consider using blender, you can do your CGI in LW or 3ds, where ever you are more comfortable, and then you can composite your CG and live action footage there.

Oh and it's free, of course

L2K

i humbly suggest using trial versions of expensive softwares. 30days of unlimited fun.
and some creative cow tutorials.

cameronfletcher

While we are on this subject, does anybody know if the background of the bridge or any other part of a star ship (inside it) is background that has artificially been put there to replace a green screen?

Or do they always use sets?

I understand green screen is used mostly if you want to render an aritificial background that is very big - an outside scene, but what about inside scene, like the walls of the bridge or the coridors of the star ship voyager?

I often noticed in TNG and Voyager that the camera is focused sharply on the actors as a close up and the back ground is a blurr, it would seem logical to me that they created a CGI background that is blurred to save time and money.

Chris2005

cameronfletcher wrote: »

While we are on this subject, does anybody know if the background of the bridge or any other part of a star ship (inside it) is background that has artificially been put there to replace a green screen?

Or do they always use sets?

I understand green screen is used mostly if you want to render an aritificial background that is very big - an outside scene, but what about inside scene, like the walls of the bridge or the coridors of the star ship voyager?

I often noticed in TNG and Voyager that the camera is focused sharply on the actors as a close up and the back ground is a blurr, it would seem logical to me that they created a CGI background that is blurred to save time and money.

Unlike Star Wars, 99% of Star Trek's sets were real... about the only fake sets, where it wasn't always there, was in cases of the holodeck, etc. but if it's a corridor it's real... now they did do some tricks of angle for the Jefferies tubes, to give the illusion of it going on forever, but as I said, 99% of Trek's sets were really there...

If the camera is focused on the actors, the background will be blurred due to the focus... it happens in real life to, if you take a camera and focus it on a particular spot...

evil_genius_180

Yeah, Star Trek is all sets. For one thing, CGI was still very much in its infancy when those shows were on the air. It wasn't until after the turn of the century that you started seeing more CG sets in movies, though that sort of thing is out of the budget of most TV shows, even today.

You should check out Star Trek: Hidden Frontier. It's a bit dated by today's standards, (though, their later seasons are higher quality) but it's kind of the father of Star Trek web-based fan series. They saved money by doing all green screen shooting and filled in the backgrounds with CGI mattes. The series creator/executive producer did a lot of it himself. I know he used Lightwave for the ship renders and effects, though I don't know what he used for the green screen stuff.

Melak

The bridge viewscreens were usually greencreened, if I recall correctly

evil_genius_180

Yeah, those were, so were any other view screens with video on them. But they did that back in the '60s.

cameronfletcher

I always found it suspicious how most of the time the camera is perfectly still when shooting actors talking.

Like they didn't like movement or else the background might get stuffed up.

You think Star Trek used hybrid sets sometimes? Like green screens to replace regions where monitors on tables and flat walls would normally be?

This way computer screens can be added in later. Same with View screens on flat walls where it's a perspective angle instead of straight on view.

How effective do you think that would be?

cameronfletcher

By the way i saw
http://hiddenfrontier.novelhost.net/701_hires.mov
It's horrible!

I can still see the green screen as outlines around the actors!

Does this mean the technique doesn't work or that it was executed badly?

evil_genius_180

cameronfletcher wrote: »

By the way i saw
http://hiddenfrontier.novelhost.net/701_hires.mov
It's horrible!

I can still see the green screen as outlines around the actors!

Does this mean the technique doesn't work or that it was executed badly?

Yeah, all of their films are that way. However, one important thing to remember is that most of those were done years ago using old software, probably whatever was cheapest. The people involved in films like that are all volunteers and they hardly ever have any money. The technique works, you just have to have good software, which you're probably going to pay a lot for.

tobian

http://dpont.pagesperso-orange.fr/plugins/nodes/Additionnal_Nodes_2.html For Lightwave: There's a colour key tool inside the DPkit, and you can always set your images to have front projection, which saves messing on with scaling issues.

That said if possible, I would recommend using a dedicated comp application, especially if there's any soft edges, like hair or fur, or you just need fine-tweaked control. The better results tend to come from professional applications.

Don't be so harsh on hidden frontier. Remember they were using cheaper off-the-shelf solutions from several years back, and most importantly low definition video. Using high def or film helps you to get cleaner mattes, and the software they have these days is significantly improved (just not always cheap or free!). They also had quite poor sets, as in a professional environment, they would cleverly design the environment so as little green light as possible would bounce back on to the actor, making matting easier, plus if you take some time you can reduce it further with extensive post work which they may not have had the skill or time to do, because unlike a real show, 100% of their shots were CG, whereas most shows only use green screen for FX shots.

tobian

http://dpont.pagesperso-orange.fr/plugins/nodes/Additionnal_Nodes_2.html For Lightwave: There's a colour key tool inside the DPkit, and you can always set your images to have front projection, which saves messing on with scaling issues.

That said if possible, I would recommend using a dedicated comp application, especially if there's any soft edges, like hair or fur, or you just need fine-tweaked control. The better results tend to come from professional applications.

Don't be so harsh on hidden frontier. Remember they were using cheaper off-the-shelf solutions from several years back, and most importantly low definition video. Using high def or film helps you to get cleaner mattes, and the software they have these days is significantly improved (just not always cheap or free!). They also had quite poor sets, as in a professional environment, they would cleverly design the environment so as little green light as possible would bounce back on to the actor, making matting easier, plus if you take some time you can reduce it further with extensive post work which they may not have had the skill or time to do, because unlike a real show, 100% of their shots were CG, whereas most shows only use green screen for FX shots.