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Hoverlay II

open hardware interactive midair screen

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This project was created on 02/26/2014 and last updated 5 days ago.

Hoverlay II is a low-cost, interactive, modular, open source vapor screen. It allows projection of images, videos and games right into midair and comes with it's own selection of interactive applications.

Even though one Hoverlay II unit is still quite handy (326 mm wide), up to 5 units can be plugged together to form a badass big 1,63 m wide, floating screen of > 1 m height. Bigger screens are possible by choosing larger wire diameters and power supplys.

See it in action here:
With interactive visuals:

First test:
Project page:

Humble beginnings:

Short explained, the box creates a thin, stable film of vaporized water, travelling upwards in a laminar flow, which then acts as a magical rear projection canvas. A Kinect sensor and a custom cyber-glove are used for the interactive stuff.

Vaporisation is done by ultrasonic atomizers, air is moved by an array of pc case fans, laminar flow is formed by 3d printed flow formers (used to be a large array of drinking straws). Rear projection works with any kind of video or still image projector.

  • 1 × AC power supply 24V AC 350W (for up to 5 Hoverlay units)
  • 8 × pc case fans 12V DC, approx. 40 CFM each
  • 1 × PVC hardfoam plates good material for building enclosures, easy to cut, easy to glue
  • 4 × ultrasonic atomizer 24V AC, approx. 14W each
  • 1 × DC power supply 12V DC 500W (for up to 5 Hoverlay units)
  • 12 × female power connectors 3,5 mm gold plated rc power connectors female
  • 6 × male power connectors 3,5 mm gold plated rc power connectors male
  • 1 × tons of screws size depends on your build
  • 1 × plastics glue
  • 1 × double sided adhesive tape

See all components

Project logs

View project log

Build instructions
  • 1

    Get the BOM list from the project page:

  • 2

    Download the CAD files for the parts from the GitHub repository:

  • 3

    add the atomizers to the vat, prepare wiring

See all instructions


Gabriel wrote 7 days ago null point

Does the air speed have influence on image quality?

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iamnotachoice wrote 7 days ago null point

I tested different flow rates by pwm'ing the fans down, finding out that a high flow rate of air results in a better image. Though, increasing the flow rate means decreasing the fog density (thus perceived brighness of the image) and needs to be compensated by adding more foggers (increasing fog density again).

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Rocket501 wrote 8 days ago null point

Awesome project! I am interested in making this. How much does it cost? Do you recommend any of the ultrasonic atomizers?

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iamnotachoice wrote 7 days ago null point

Thanks! My recommendation would be: use the strongest and most rugged foggers you can find or afford for this application. I honestly cannot recommend the ones I used, still looking for better ones. Will be glad to see another build, feel free to contact me if something's unclear.

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Adam Fabio wrote 16 days ago null point

Hoverlay is looking better and better every time I see it! Thanks for submitting it to The Hackaday Prize! Your superstring video is just incredible! Don't forget to keep the updates rolling in for the contest - you might just find out how well hoverlay works in space!

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iamnotachoice wrote 16 days ago null point

Thanks a lot! Be assured I keep you guys updated!

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anfractuosity wrote 2 months ago null point

Very cool! I'm curious if you could use multiple projectors somehow to get 3D?

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iamnotachoice wrote 2 months ago null point

There is a nice effect you can get with this by shooting onto the screen with two projectors from back and front. That setup could at least show you an object from --- wait for it :) -- back and front. I also tested shooting in there with two projectors from slightly different angles. That however does not yield good R/L channel separation for the spectator (actually you wouldn't call that "channel separation" anymore), the fog is just too diffusing. Using a regular 3D projector with active shutter glasses gives good results though.

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Mike Szczys wrote 4 months ago null point

Early prototype is fantastic! Can the ultrasonic atomizers be used continuously for long periods of time?

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iamnotachoice wrote 2 months ago null point

Depends on your definition of "long periods of time". It works for many hours (gets warm though). The membrane wears out due to mechanical stress and scale sooner or later, but can be replaced in most foggers.

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akohlsmith wrote 5 months ago null point

Trèz cool. Is the top of the laminar flow distorting due to the ambient air not being still? I don't know enough about laminar flow to know the limitations.

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iamnotachoice wrote 5 months ago null point

Thanks! The quality of the fog wall is best in still air. Though the laminar flow is quite robust against slight ambient air streams, it's steadiness will decrease a little, but it still works good enough for getting a picture.

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