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A point of view on Persistence of Vision

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Introduction

Persistence of Vision (PoV) displays have all become the rage these days, with many calling/marketing them holographic displays. These are generally LED displays which ‘shows’ images by displaying a section of an image at a given time, in quick rapid succession. The human brain perceives this as display of a continuous image. Display of successive images gives the perception of moving image aka video. This post would try to give a point of view on this class of displays.

Current state of the art

  1. Kino-mo Hypervsn:
    1. Features:
      1. 2D high density color LED rotary display.
      2. Can sync across multiple modules to create a bigger display.
      3. Can provide an illusion of holographic content.
      4. Remote management and deployment of content via WiFi or 3G. Push to multiple locations (See this demo video)
    2. Cost: Approximately 3000.00 USD according to this demo video.
  2. Holo2Go HoloBlade2:
    1. Features:
      1. Similar features as Kini-mo Hypervsn
      2. 19″ and 24″ displays available
      3. WiFi enabled
      4. Can hold up to 8 GB of content
      5. Have mobile apps and software for PC and Mac for control and update content
    2. **Cost:**842.00 USD
  3. voLumen:
    1. Features:
      1. 3D color LED rotary display.
      2. True 3D volumetric display (if you can accept PoV in this realm).
      3. Can take 3D animations made in software like Cinema 4D and playback.
    2. Cost:
      1. Not available. Was a Hackaday project sponsored by multiple companies.
      2. If one were to estimate to build a single display, the LEDs required by itself would cost about 160 – 170 USD (excluding shipping and customs). And easily a minimum of 4 to 5 months of development time.

Others

  1. Utorch FY3D – Z1:
    1. Features:
      1. Similar to Kini-mo Hypervsn, less the sync across modules capability.
      2. 42 cm diameter fan.
      3. Reviews – Youtube videoBudget Light forum.
    2. Cost:
      1. 319.99 USD (as on 16th May 2018) for Utorch FY3D – Z1 (no WiFi)
      2. 480.86 USD (as on 16th May 2018) for Utorch FY3D – Z2 (with WiFi)

Low cost | DIY

  1. Adafruit MiniPOV 4 Kit – DIY Full-Color POV and Light Painting Kit:
    1. Features:
      1. 8 pixel RGB linear PoV or Light Painting module
      2. Need to upload firmware to change design
    2. Cost: 24.95 USD
  2. A lot of builds can be found on HackadayInstructables, etc. Cost and time will vary from build to build.

Summary

  • There are a lot of ready-made decent to cutting edge quality PoV systems available to purchase from about 300 USD to 3000 USD. This is not withstanding the Chinese clones.
  • Almost all PoV systems require either video files or converted video files to run. Transmission via USB programming, SD card, WiFi, etc. There seems to be no version which just poses as a display output/screen.
  • Compared to proper displays, the resolution is going to be abysmal.
  • The only attraction is that not many people have seen such displays in action. After the initial novelty wears off, don’t know how much attraction it can retain. Especially considering that for 300 USD, you can get a 43″ 1080p display these days.
  • Mechanical issues could be a real problem as well as power/data distribution in medium to long term (Slip ring or brush systems can wear down).
  • There are safety issues with non-enclosed versions due to high speed spinning blades.
  • Need dark environment with black background to work the best. Many low brightness displays can have issues in well-lit locations.
  • Currently we have not found a display which can confirm streaming content in real-time or real-time control.

Recommendation

  • To consider such displays, one needs a well defined contextual use case for it to make sense.
  • Real-time display is difficult to implement due to the operating principle.
  • Not to be treated as a screen replacement.