Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: volumetric fog screens (existing and ideas for improvements)

  1. #1
    Join Date
    Jan 2019
    Posts
    1

    Default volumetric fog screens?

    Update: I had to remove post as this was just misinformation. Sorry if I got anyone interested in this project. My tests concluded the same as another research paper, that the Mie scattering angle is much higher for a true multiview fog screen to work.
    The researchers from the video weren't very honest with positioning of the individual video projectors. Because a single color character was displayed and camera capture wasn't great the high amount overlap between each view as the camera was moving around the setup wasn't very obvious. In real life it's unusable. Maybe you can get a new view each 60 degrees but then it becomes pointless.
    Last edited by caimgin; 02-24-2019 at 00:52.

  2. #2
    Join Date
    May 2007
    Location
    1 hr from everything in SoCal
    Posts
    2,753

    Default

    For good laminar flow, high pressure and high speed is bad. As airspeed increases, so does the Reynolds number. You want as low a Reynolds number as you can get. High volume at low speed is key. Having built my own fogscreen from scratch I can tell you, fog is probably not the best medium to use. It is super susceptible to air perturbations and it doesn't dissipate as fast as you would need if it were in an enclosure. Even with high quality fog transducers, there is still a LOT of water to deal with.

    Condensation is a major bitch. The fog blowing upward would be even worse as the condensation would drip down the straws and make a mess but even more so, would hinder the fog flow as the water drops collect on the walls of the straws, form a meniscus and destroy a lot of the laminar flow. I can speak from experience as I have had to battle with this.

    Even at 15fps, articulating fog is out of the question. With all of the issues with the fog itself and creating/keeping a laminar flow, mie scattering would the the least of your worries although, should be considered as another deterrent. Using fog as a projection medium in general is the wrong way to go, IMO. The only reason I use it is the novelty of being able to walk through it.

  3. #3
    Join Date
    May 2007
    Location
    1 hr from everything in SoCal
    Posts
    2,753

    Default

    Out of the box thinking, for sure. I agree with you on the multi-projector shortcomings although you could correct that by have multiple z angle projectors as will. I imagine that would really start to mottle the image with the stray scatter lighting up the water particles similar to rayleigh scatter. But yeah, we still have a long way to go to get holograms where we need them. The cool thing with trying out fog is, it is pretty inexpensive to knock out rough prototypes. Better do it soon though, the US is getting nearer to outlawing plastic straws!
    Last edited by absolom7691; 01-29-2019 at 12:21.

  4. #4
    Join Date
    Nov 2008
    Location
    Cleveland Ohio
    Posts
    2,599

    Default

    For a small volume, a few drops of milk in water in a fish tank works very well. I mean like 1ml milk in 50 gal water. You need very little and it lasts a long time

  5. #5
    Join Date
    Apr 2009
    Location
    North of Jackson Michigan USA
    Posts
    363

    Default

    Has anyone tried aerogel?
    Runs with Lasers

  6. #6
    Join Date
    Nov 2008
    Location
    Cleveland Ohio
    Posts
    2,599

    Default

    too expensive, too dense even as light as it is( in a thick cube), too hard to get or make, and you would be really amazing if you could make a piece as large as a laser screen.

    https://www.youtube.com/watch?v=X24np30GS2o

  7. #7
    Join Date
    Apr 2009
    Location
    North of Jackson Michigan USA
    Posts
    363

    Default

    Yeah, that was my conclusion as well; just wondered if anyone had tried it.
    Lotsa really dangerous and expensive chemicals involved.

    I was thinking of a ~2' cube on a pedestal, in an enclosure, lit with lumia from below.

    I will be proposing this to the UM School Art/ Chemistry as an art project.
    Maybe they can figure out how to do this.

    Cheers...Mike
    Runs with Lasers

  8. #8
    swamidog's Avatar
    swamidog is online now Jr. Woodchuckington Janitor III, Esq.
    Join Date
    Nov 2006
    Location
    santa fe, nm
    Posts
    1,545,752

    Default

    it's expensive and it tastes awful.

    Quote Originally Posted by clickamouse View Post
    Has anyone tried aerogel?
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

  9. #9
    Join Date
    Aug 2008
    Location
    UK
    Posts
    5,704

    Default

    Interesting, although isn't this just another take on Peppers Ghost? In which case there are better ways to achieve this:

    https://www.youtube.com/watch?v=1pjZ98p9k3c

  10. #10
    Join Date
    Nov 2008
    Location
    Cleveland Ohio
    Posts
    2,599

    Default

    I saw your post when you first put it up and read it as ghost peppers. I had absolutely no idea what you meant and moved on. On a whim I clicked the link today expecting something ridiculous. Opps. I sure read that wrong. Never heard of that method before and it is amazing. Thanks for sharing.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •