Tony Annunziata

Anthony_VFX_CGI Posts: 56 Just Starting Out*
edited February 2018 in Practical Filmmaking

Greetings HitFilmers, I am wondering if folks have any thoughts on recreating this practical effect as a visual effect. It entails Fred Astaire dancing, then stepping on the wall; dancing some more; then again onto the ceiling, until he works his way back down the opposite wall onto the floor.  Attached is a video showing the practical effect: A spinning room. Could this be done with a virtual spin in HitFilm? I know it’s easy enough to spin a room and green screen an actor. But what could be done to ensure that stepping onto a 90 degree angle looks real?



  • tddavis
    tddavis Posts: 5,222 Expert

    @Anthony_VFX_CGI I think a green box big enough to dance in woukd be easier to gimbal spin than a whole room and if the actor dances in place on the horizontal plane it could be made to look like he's traveling across a larger room with keying and whatnot but I doubt anything will be as good as Astaire did on a sound stage.  

  • CleverTagline
    CleverTagline Posts: 3,342 Ambassador
    edited February 2018

    @tddavis I get the impression that @Anthony_VFX_CGI doesn’t want to build a gimbal, but a static green screen space and cheat the rotation in post. I can think of a way to pull it off, but it would require very careful lighting and camera work. 

    The actor performance would be fairly easy to set up. You have a space set up with green walls and floor. Say the person is moving to the screen right wall to walk up it. Place a couple small tape marks — one on the floor, one on the wall — where the actor will place their feet while making the transition. Record them going through the motion as though they’re about to start walking up the wall. Then do the same thing on the left wall, placing marks in similar positions (carefully measured) and record the actor doing the second half of the action, now acting as though the floor of the green screen set is the wall of the real room.

    In HitFilm, the second clip would be rotated left 90 degrees, and positioned such that when you cut from the first clip to the second, it looks like the performer moves from the floor to the wall. If you cut in the middle of a move by the actor, the transition should be fairly clean. If needed, you could possibly use the Puppet tool (a Pro-only feature) to help match performer poses from floor to wall. 

    As I said before, though, camera positioning and actor lighting between the two clips are going to be what’s tricky. You could always rotate the camera before capturing the second clip, but making sure the lighting is consistent will still take some work. 

  • Anthony_VFX_CGI
    Anthony_VFX_CGI Posts: 56 Just Starting Out*
    edited February 2018

    Thanks for your thoughts on the matter, @tddavis and @jsbarret.

    I was hoping to move this from practical effect in principle and more to a visual effect in post, @jsbarret.

    I was thinking of a "unfolded room," where the dimension of the four walls are "laid out" flat on the ground. This would entail a large green screen layout.

    To approximate the gravitational shift in weight when stepping from floor to wall (and so forth) that would occur in an actual rotating room, was thinking of a see-saw type mechanism, or more accurately, an L-shaped board where you can step on one side and ride it back down to the floor. At that juncture, the footage layer and virtual room could be rotated in HitFilm to make it appear the dancer is now standing on the wall. The L-board could be masked out, or painted green and keyed out. Perhaps the L-board could even be tracked and the virtual room parented to its point layer, so as L-board tilts and collapses the scene does too?  

    I believe this would be tricky but feasible. Yet as I sort through this "90 degree, wall-stepping" issue,  another issues arises. This is going to need very carefully thought out camera work. The shot necessitate the camera be stable, ideally at the center of the room, the axle point of the room rotation. Yet as I have conceived it, the camera has to pan along the length of the "unfolded" room. Even if I were able to mark the center points of that room (and hit that mark four times for a complete rotation), a pan by definition is moving and would be off-center in between center points.

    However, like any insertion of live action into a 3D scenes, this may be a matter of getting a good match-move, camera solve (in mocha) via green screen markers. Then if the camera pan and the rotation are timed right, the illusion might be sold. 

    Anyway, those are my current thoughts on the effect. Thanks again for yours @tddavis and @jsbarret.

    I'm still open to other ideas or concerns. I'm of the mind work smarter, not harder; so I'm all about thinking about this ahead of any attempts. (smile)


  • Anthony_VFX_CGI
    Anthony_VFX_CGI Posts: 56 Just Starting Out*

    @jsbarret, that's an interesting idea to use the puppet tool, if need be, to tweak minor dancer movements back in sync and help obscure a cut. Lighting might need to be the flattest, most even possible on the dancer. It can then be added for style in post to match the source of light in the virtual room.

  • Perhaps a half way solution between virtual and physical

    Construct a 'rocker' consisting of two sturdy plates at 90 degrees to one another and paint that green - literally what you would get if you took two adjacent faces of a cube and threw away the other four faces. It can be small - just enough space to for the footwork during the tip phase.

    I have seen plenty of acrobats and kids do something similar - jump with the leading foot onto the vertical face to start the tip whilst then placing the other foot on the face that is now rising, not sure how much a skilled acrobat could slow it down, I suspect you need a certain level of 'attack' to get the tip going past the point of no return.

    The dancer does not have to stay within the bounds of the device they can then dance off seamlessly once they have done the tip.


  • Anthony_VFX_CGI
    Anthony_VFX_CGI Posts: 56 Just Starting Out*

    Yes, @jonnie45! This is similar to what I was describing, and I'm intrigued enough by this idea of a simple "rocker" prop, used to approximate the 90-degree-wall-step, to test it out. 

    I am deliberating on how much space is actually needed. I agree you would not necessarily need much space; e.g., no need to unfold a 10x10 room across 40 feet. You could just green screen around your dancer, as well; no need for an expansive green screen set. I think this is especially true if you just want to capture the shift in planes, that 90 degree step. Once on the wall (or ceiling) you could cut as you see fit and adjust the dancer's position as necessary. But this is trickier if you want to maintain a constant camera shot, with no cuts, like in this Astaire piece. 


  • Triem23
    Triem23 Posts: 20,292 Power User

    One thing that's going to be tricky about shooting this greenscreen is going to be the lighting rig. Somehow the lighting rig is going to need to spin around to appear to move with the light's room sources. No practical solutions at this point, just the observation that  if the light direction isn't reasonably close to what the room would have, the composite won't work. 

  • Anthony_VFX_CGI
    Anthony_VFX_CGI Posts: 56 Just Starting Out*

    Thanks for your thoughts, @triem23. Ya got me giving it a think. I agree the lighting might be tricky in post, particularly if the lights must spin with the virtual room. However,  I’m not so sure we’d need a  virtual, rotating light rig if going for a recreate of this Astaire scene.   Not that you’re implying they did, but I doubt they built a rig to spin with the room.  The lighting is pretty harsh. It appears the key lights shine directly in the box, camera level, casting some strong dancer shadows.  The lamp lights are pretty exaggerated too. They were probably trying to get some backlight from them.  This was literally a box missing one wall. I bet there was little choice but to flood the room with light head on.  I suspect such lighting would translate into nasty spill with a green screen.  We’d have to do all the usually lighting to separate the subject from the background green screen; then light the subject evenly too; really plain vanilla.  If trying to recreate the Astaire scene, stationary lights might be what's needed. Perhaps just flood the virtual room with a key or two located near the camera? Then perhaps add some flare effects and masks parented to tracked lamps?