Changing perspective: custom-built set, greenscreening or lens trickery?

Discussion in 'Professional Video Production' started by Jacques E. Bouchard, Jun 23, 2008.

  1. I'm preparing to shoot a 5-min. short and I'm faced with a technical
    challenge: as the story progresses, I need to make the room seem smaller.
    I've thought of doing this in one of three ways:

    1) build fake walls and move them closer as we shoot. While this is
    technically the simplest solution, it's also the most expensive;

    2) greenscreen the background. While I have the equipment, this is the
    most daunting solution, as I only have basic greenscreen experience and I
    need the background to "move" with the camera as it moves around the
    room. I know the theory of motion tracking with After Effects, but I'm
    worried the end result might look fake even with careful planning;

    3) using lenses to play with perspective. I could start with a wide angle
    adapter to get all of the room in one shot, and finish with a zoom for
    tighter shots and compressed perspective. I could also play wiht depth of
    field. This is by far the cheapest alternative, although I'm not sure how
    dramatic the effect would be. I'm working in an actual room with four
    walls and there's a limit to how far back I can set the camera to zoom in
    the most - plus, it's a 20X20 room, I can only compress perspective so
    much.

    Any ideas/advice? I'm not shooting until late summer, so there's plenty
    of time to build fake walls/read FX manuals/test lenses, depending on my
    solution of choice.


    jaybee
     
    Jacques E. Bouchard, Jun 23, 2008
    #1
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  2. Jacques E. Bouchard

    Ma3rk Guest

    It all sounds tricky, but most all of this just boils down to picking it apart and see what’s really needed to sell the idea.  Not every shot needs to be an effect, and often simple planning as to how a sequence will cut will reveal how you can get away with the minimum.




    I think at this point you should take the next step of going from a written thing to something visual to see how/if it translates.  Storyboards do have a function still, and working out an animatic is pretty easy these days.




    Totally different from your shoot, but as an example/inspiration using off-the shelf hard & software, this is what can be done pretty readily these days w/ just a little planning.

    http://kk.org/ct2/2008/01/extraless-films.php





    I imagine for your shrinking room you’ll end up doing all the things you mention plus a few more.  Whether it's a comedy or Twilight -Zonesque piece will make a difference too as to how you approach it too.




    Keep us posted; it sounds like a fun project.




    Mark











    Jacques E. Bouchard wrote:

    I'm preparing to shoot a 5-min. short and I'm faced with a technical challenge: as the story progresses, I need to make the room seem smaller. I've thought of doing this in one of three ways: 1) build fake walls and move them closer as we shoot. While this is technically the simplest solution, it's also the most expensive; 2) greenscreen the background. While I have the equipment, this is the most daunting solution, as I only have basic greenscreen experience and I need the background to "move" with the camera as it moves around the room. I know the theory of motion tracking with After Effects, but I'm worried the end result might look fake even with careful planning; 3) using lenses to play with perspective. I could start with a wide angle adapter to get all of the room in one shot, and finish with a zoom for tighter shots and compressed perspective. I could also play wiht depth of field. This is by far the cheapest alternative, although I'm not sure how dramatic the effect would be. I'm working in an actual room with four walls and there's a limit to how far back I can set the camera to zoom in the most - plus, it's a 20X20 room, I can only compress perspective so much. Any ideas/advice? I'm not shooting until late summer, so there's plenty of time to build fake walls/read FX manuals/test lenses, depending on my solution of choice. jaybee
     
    Ma3rk, Jun 25, 2008
    #2
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  3. Will do. I'll probably go with perspective, angles and compressed
    perspective as I'm not looking for too litteral a visual effect.


    jaybee
     
    Jacques E. Bouchard, Jun 25, 2008
    #3
  4. Google the phrase "Ames Room illusion". This is a low-tech way to do
    it, but there's nothing cheesy about it: it was used extensively in
    Lord Of The Rings for inside the Hobbit Hole Home.

    Back in the 50's and 60's, what some studios tried was to shoot a
    miniature set with one camera, and a full-size actor on another camera
    right nearby, the two cameras were electro-mechanically linked so the
    lenses, iris, and zooms would stay matched live in real time. You them
    luma-keyed the actor into the miniature set, live. To pull this off
    required very tight tolerances; any little bit of slop int he linkage
    system gave away the trick.

    Today, we'd usually chromakey people into a 3-d computer-generated
    room, or a 2.5-D room, made of a composite of 2-Dimensional photoshop
    files, composed into a 3-d space. From the viewpoint of the virtual
    camera, the set looks photoreal. Because it is made of real photos.
     
    nobody special, Jun 30, 2008
    #4
  5. Thanks, very interesting. However, since I'm working in an existing room
    (rather than a set), it's not feasible for my needs.


    jaybee
     
    Jacques E. Bouchard, Jul 1, 2008
    #5
  6. What's not feasible about a gallon of paint and some masking tape to
    make the warped checkerboard floor?
     
    nobody special, Jul 2, 2008
    #6
  7. Because this is an actual room in an actual apartment and I can't paint the
    hardwood floor.



    jaybee
     
    Jacques E. Bouchard, Jul 2, 2008
    #7
  8. Jacques E. Bouchard

    Larry in AZ Guest

    Waiving the right to remain silent, "Jacques E. Bouchard"
    Lay down a cheap floor covering, maybe some old dance matting, and paint it.
     
    Larry in AZ, Jul 2, 2008
    #8
  9. That still won't let me cheat the perspective with the moldings on the
    walls, the fireplace, the door, etc.

    As effective as that method may be on a set, it's not at all suited for
    an existing room.


    jaybee
     
    Jacques E. Bouchard, Jul 2, 2008
    #9
  10. OK then you'll have to cowboy-up and use greenscreen. Take very high
    rez still photos of each wall and the floor and ceiling (if you can,
    actually you can create a new floor in photoshop so no biggie there).
    Take good photos of all the furniture the same way, if the furniture
    is to also change dimension, otherwiese, forget that part...

    Then load these pictures into the compositing program of your choice
    and map them to the sides of a large virtual cube. Chromakey your
    actor into the cube. Use more photoshop and adjustments in the
    compositor to shrink the walls any way you like. This is most easily
    done if you lock down the camera shots and don't zoom, tilt, or pan,
    but instead use all cuts. However, if you're willing to do the extra
    work, motion track the green screen and actor, apply the motion files
    to the room, and they will movetogether in synch to create a decent
    illusion. This costs only your time and enough green screen cloth to
    back up your actor and the furniture.
     
    nobody special, Jul 2, 2008
    #10
  11. Jacques E. Bouchard

    Larry in AZ Guest

    Waiving the right to remain silent, "Jacques E. Bouchard"
    Then, you're hosed and may need to look at someone's "Virtual Set"
    solution for the answer. That, or modify your expectations...
     
    Larry in AZ, Jul 2, 2008
    #11
  12. I looked into that, and that was my second choice. However, because of my
    limited experience with a green screen, I'm worried things won't work out
    in post-production when it's too late to re-shoot.

    I decided to go for a subtler effect using lenses to mess with distortion
    and perspective.


    jaybee
     
    Jacques E. Bouchard, Jul 2, 2008
    #12
  13. If money was no object I would have built a set and simply moved the walls.
    For now, I'll do some tests with lenses to play with perspective. I have at
    least two months before we shoot, so there's still time to explore
    possibilities - or find generous sponsors.

    Anyone got a couple of grands burning a hole in their pocket? ;-)


    jaybee
     
    Jacques E. Bouchard, Jul 2, 2008
    #13
  14. Jacques E. Bouchard

    Bill Fright Guest


    so get your elements together before the shoot. This way you can work
    the perspective live while you shoot. This way you'll know it's right.
     
    Bill Fright, Jul 3, 2008
    #14
  15. You have plenty of time to test and learn with greenscreen. The trick
    is to light the green very evenly, and to put your actor far enough
    away from it so as not to throw a shadow on it nor pick up colored
    reflected spill light off the green. Cloth or paint is cheap. The NLE
    you use probably already has an adequate green effect built in.

    Why not do a simple test in photoshop? All you need is a still camera.
    Shoot the room as I described before, shoot your actor against a plain
    backdrop and cut them out to make a file with an alpha channel. Make
    one multilayered photoshop file, with a wall on each separate layer.
    Use "free transform" to turn the walls and create a 3-d-box of a room.
    Layer you actor cutout into it. Now use your mouse to move the virtual
    walls inward and play with the image a little. You can do it.

    Then bring the photoshop files into your NLE and try it there.

    Costs you nothing but a few hours to find out.
     
    nobody special, Jul 4, 2008
    #15
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