Project Straylight

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Contents

Goal

To build a $500 educational project to display and demo at the upcoming EDExpo (late February 2015)

Plan

Build a portable, RaspberryPi based Lightboard for recording lessons/lectures/demos. A lightboard allows the instructor to write on a whiteboard in front of them while facing the camera. See: Northwestern Lightboard for examples

Demo videos: [Youtube|https://www.youtube.com/watch?v=ZsAPPUVK-DY&list=PLqATPiC_Bcl-t8vrzZlnGi3HTurs9Yuf3]

Status

The basic lightboard is assembled and working.

The RaspberryPi and camera is set up to automatically boot into camera preview mode with the image flipped horizontally.

Project Description

A lightboard allows an instructor to record educational material to be presented online (either streaming live or after additional post processing and editing) in a natural manner. Notes and diagrams are easily written directly on the transparent board between the presenter and the camera, without the need for the presenter to turn their back to the virtual students (as in a traditional classroom setting with a whiteboard behind the presenter).

The presenter writes and draws naturally in their own handwriting as the camera handles flipping the image horizontally before the student views it. The real-time preview screen aids in the presentation. It is like watching oneself in a mirror instead of a traditional studio monitor that is inverted left to right. Additionally the text drawn on the lightboard is seen immediately in the same orientation as it will be viewed by the students.

The edge lighting of the transparent dry erase board creates an effect of bright, clear letters easily viewable that appear in midair in front of the presenter and the black background. The dark solid background also allows for easy insertion of images using post production video editing software, or through a hardware video mixing board.

Project Straylight is built using commonly available aluminum extrusion sections holding a sheet of ¼” acrylic, RGB LEDs for edge lighting, and a RaspberryPi single board Linux based PC with an inexpensive HD camera. The backdrop is heavy black canvas fabric on a PVC frame. In a studio environment, the back wall could be painted a matte black finish instead.


Budget

RaspberryPi Recording

  • RaspberryPi B: $35
  • RaspberryPi Camera: $30
  • Monitor with HDMI input: $100
  • Powered USB Hub: $10
  • USB sound card for recording: $10
  • Microphone: $15
  • HDMI and misc cables: $20
  • RaspberryPi Mount: $0 (3D printed)
  • VESA Mount to monitor: $0 (Laser cut from scrap acrylic)
  • Software: $0 (all open source)

Lightboard

  • 3x6" .220" thick Acrylic: $100
  • 25mm extruded aluminum frame: $80
  • LED lighting strip and power supply: $25
  • Neon EXPO dry erase markers: $15
  • Black canvas for backdrop (2.75 yards): $10
  • PVC for backdrop stand: $15 (estimate as this was scrap)
  • Baskets for markers: $5
  • Misc screws and brackets: $25

Total: $495

Todo/Version 2

Software

  • Video mixer to be able to overlay images into the background in real time
  • Experiment with the RaspberryPi cameras settings for white balance, image stabilization, etc for optimal recording
  • Script that automatically starts and stops recording of video and audio on a trigger
  • Script to mix the audio and video into a single file for easier post-production
  • Auto-mounting of a USB thumb drive at boot time and set this as the default location for recordings, or post-mixing drops to eliminate users from needed access to the RaspberryPi

Hardware

  • Give the presenter a remote control to start and stop recording from behind the board. Keyboard or mouse would be fine.
  • Redesign the floor mounts of the board to be sturdier and to allow for a heavier board
  • Use tempered glass instead of acrylic for better long term durability (current budget wouldn't allow for this at approximately twice the cost, plus twice the weight)
  • Edge light with solid white LED strip instead of RGB strip (RGD was available so was used although not necessary)
  • Add a second RaspberryPi/monitor/45degree piece of acrylic in front of the camera for a teleprompter
  • On-air light: Add a red LED to the VESA mount, hooked into a GPIO on the RaspberryPi, that can be turned on and off via script. This will edge light the mount with a red glow when the Pi is recording.
  • Add WiFi and set up Network Time Protocol (NTP) or add a real time clock (RTC) to the Pi so the time stamping of files is accurate.
  • If Lightboard is set up in a semi-permanent location (The podcast studio?) set up better ambient lighting for optimal recording
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