Illusion of depth with video projection

Discussion in 'Multimedia, Projection, and Show Control' started by Gambino, Jul 16, 2019.

  1. Gambino

    Gambino Member

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    Hi! Newbie here.

    I'm doing this show where we need give the illusion that there's an extra room beyond the back of the scenario where some stuff is happening during the show.

    For this, at the back of the scenario there's an openning, about 3 meters x 3 meters, where the projection of this "room" will be.

    It's very tricky because this illusion must be the most realistic possible. I want to use rear-projection with a grey or dark grey rear-projection screen as I feel it's very important to maintain the dark areas of the image really dark. More than the highlights to be white I'm guessing.
    I'm also shooting all the footage for that projection so I'll be controlling that part.
    Does anyone have some tips or advices regarding this matter. I'm really focused in getting really good ratio between really dark shadows and bright highlights on my projection.
    Thanks guys
    Gambino
     
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  2. Amiers

    Amiers Renting to Corporate One Fixture at a Time.

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    It’s all about that good content.

    High Res image with a high contrast ratio projector.

    Then you have to make sure you have 0 bleed from your front wash and downlights.
     
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  3. RonHebbard

    RonHebbard Well-Known Member Premium Member

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    @Amiers @Gambino and possibly @ruinexplorer What are your thoughts on a BLACK RP screen as used to be available from Rosco Lab's and likely others. With Rosco's BLACK screens viewing angle was an important consideration. I'll butt out now and crawl back in my cave.
    Toodleoo!
    Ron Hebbard
     
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  4. Amiers

    Amiers Renting to Corporate One Fixture at a Time.

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    That’s out of my wheel house for screen color. I just unpack it set it up and frame the projector.
     
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  5. ruinexplorer

    ruinexplorer Sherpa CB Mods Premium Member Fight Leukemia

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    You could go with something like a black RP, as long as you have the room for rear projection in the first place. If you are looking for front screen, I have been impressed by Screen Innovations Black Diamond series. As it is an ambient light rejecting material, you will need to place projectors low and lighting high to get the best effect.

    The rule that you need to follow is contrast perception. You need to make sure that you keep almost all light off of the screen possible besides the projected image. You need to look at the actual ANSI contrast ratio of the projector. This will be much lower than what most manufacturers will show you (the full on : full off ratio). You need a dark surface that will absorb as much ambient light and video black as possible.

    Is the room just going to be viewed or will there be performers that need to be lit?
     
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  6. BillConnerFASTC

    BillConnerFASTC Well-Known Member

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    I've seen some incredible depth in (front) projections on scrim. Play with it.
     
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  7. Gambino

    Gambino Member

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    Only saw a couple of videos of the Black Diamond series and they are impressive, kind of magical stuff actually!

    black RP as in black rear projection right? I'll have a rear projection that is about 4 meters away from the surface. Do you have any clue about how many lumens would I need if it is a black screen? I know the contrast of projector is key but power must be an important variable right? How can see the ACTUAL ANSI contrast of a projector?

    @RonHebbard never tried it. I would love to do so. For this kind of work I think it might be the best thing. If you need the black to be black, then having a black surface might be the best option. But I guess it also depends on on the ambient light on the show. The less the light the more "black" must be the surface I'm guessing. I was looking at one from an italian fabricant called Peroni called Notturno. Not that much expensive but then again I never tried it and can't test it out to see the actual result.

    Cheers everyone
     
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  8. macsound

    macsound Well-Known Member

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    If you have the space, rear projection with the screen a few feet behind the opening and larger than the opening by about 20% on each side. Then a scrim about halfway between the opening and the screen.
    I'd just make sure your scale is right. That's the toughest part of projection with people in a space with actual people that I've experienced.
     
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  9. Gambino

    Gambino Member

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    Yup that's the other thing that is boggling me is the scalling! I'm shooting a 5k image so that I can have more room in cropping it in post.
    @macsound not shure I understood the scrim between the opening and the screen why do you recommend it?
     
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  10. ruinexplorer

    ruinexplorer Sherpa CB Mods Premium Member Fight Leukemia

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    Yes, black rear projection material.

    The amount of lumens depends on a couple of factors. How big of an image are you hoping to create (you only stated the size of the opening)? How much ambient light will be near the screen? Will your imagery be bright or dark? A lot of how we see an image depends not only on the image itself, but what is around it. If the scene near the projection is bright, the projected image will appear darker. This has nothing to do with ambient light on the screen itself. My go to is 50-70 lumens per square foot (540-750 per square meter) of light transmitted to the audience. The black diamond material is front projection only. I haven't used it, but Rosebrand has a black material. It has a fairly narrow viewing angle (30 degrees), but has a pretty good transmittance. Actually, with a 0.9, I would tend to worry about having a hot spot, so you may need to play around a bit with that. But, with having a narrow opening for the audience to view, this might be a good fit. Depending on your size, content, and other surrounding factors, you could probably should have about a 10,000 lumen projector with a screen size of 3m x 5m (16:9 ratio). You could get by with less, but you shouldn't need more.
     
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  11. Gambino

    Gambino Member

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    Spot on @ruinexplorer forgot to mention it's a 4:3 aspect ratio with a 4 meters x 3 meters size (I'm in Portugal, we have metric) I was aiming at that 10000 lumens since the theatre venue has two panasonic projectors with 10000 lumens each. I've considered getting these two projectors lined up to make one projector but I reckon it's not going to be necessary.
    Well the images are going to vary a bit but it's mainly a dark ambiente, kind of a basement feel where i'll have some lighting to do.
     
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  12. ruinexplorer

    ruinexplorer Sherpa CB Mods Premium Member Fight Leukemia

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    Excellent. I would recommend getting a sample of the material. Make your image size of the projector to your target 4m x 3m. You will need to attach your sample to some other material so as to not be blinded by the rest of the projected light. Take a look at your image under a couple of lighting looks. I imagine that this will be what you are looking for.

    I forgot to answer about ANSI contrast. This is a measurement of light to dark with an image consisting of 16 squares being a checkerboard pattern of full black and full white. Ideally, you measure using a light meter that measures the reflected light as opposed to incident light. The light is measured from the center of each square and the measurements averaged. LCD projectors would probably measure in around 400:1 while a 3-chip DLP might measure around 550:1.

    The question about the scrim is to break up the light a little bit. Sometimes a projected image can almost look hyper real. Diffusing the image slightly with a black scrim might make it look more realistic.

    Also, though you are filming in 5k, and you mention that you will be cropping, I recommend that your content be rendered in the native resolution of the projector.
     
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  13. Gambino

    Gambino Member

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    @ruinexplorer really valuable information. You guys are amazing. I'll upload some photos once the show will be all put together.
    I was thinking about that scrim and I am astonished by it. So you say to use it to take off that crisp digital feel to the projection right? To soften it up a bit? Pure genious
     
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