Turn your webcam into a black or white board using cam_board

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kacpertopol cam_board hackgence

Point your laptop webcam at a piece of paper and the program will stretch the writable area over the whole screen.

REQUIREMENTS

python 3
opencv, numpy

Project Repository

GitHub : github.com/kacpertopol/cam_board

https://raw.githubusercontent.com/kacpertopol/cam_board/master/to_print/a4.pdf

USAGE

Prepare paper

Print to_print/a4.pdf or to_print/a4.svg on A4 paper. The small circle marks the top left part of the page. If the aspect ratio of your webcam is different from 16:9 or you want to use paper with a different size see setting up the page with markers

Setup web cam

Tilt your webcam so that all 4 ARUCO markers are in its field of view.

IMPORTANT: To use the script with Zoom, Skype, MS Teams, … Disable the camera in these programs first, before running the script. Otherwise, a “camera busy” error will be thrown.

Run cam_board

In the terminal navigate to the cam_board directory.

To launch the script:

<USER> $ ./cam_board

To run in full screen mode:

<USER> $ ./cam_board -f

To run in full screen mode and invert colors:

<USER> $ ./cam_board -fi

To run in full screen mode, invert colors and apply sharpening kernel:

<USER> $ ./cam_board -fki

To run in full screen mode and white board mode:

<USER> $ ./cam_board -fd

To run in black board mode:

<USER> $ ./cam_board -di

To display command line options:

<USER> $ ./cam_board -h

Key bindings

“q” - quit
“s” - save screen to PNG files to create slide show
- the names are chosen automatically 0001.png, 0002.png, …
- by default the files are saved in the current working directory

Adjust the configuration file

Edit aruco_cam_config to change settings.

Custom page

You can make your own marker page with the markers from to_print/symbols. They should be placed in corners of a rectangle that matches the aspect ratio of your web cam. Careful: the orientation of the symbols is important and they might require rotation - see a4.svg for reference.

Conserve printer ink / toner

tape one printout with the 4 markers to desk surface (make sure the circle is positioned correctly and use tape that can later be removed from the desk surface without damaging it)
once the script recognizes the 4 ARUCO markers and stretches them to the whole screen place a blank sheet of paper over the taped printout
if the camera moves, remove any paper covering the printout and the program will recalculate how to warp the camera image

Better resolution at the bottom

laptop stands that allow tilting might help position the camera more perpendicular to the printout with markers resulting in better resolution at the bottom of the printable area
manipulating the position of the laptop might damage it, be careful :-)

Python version error

In some linux distributions python 3 is the default. If that is not the case on your system you can:

adjust the first, hashbang, line of cam_board or …
… run through python 3:

<user> $ python3 ./cam_board

MISCELLANEOUS

ArUco markers made using this
This is a simple script bodged togather from various opencv tutorials, here is a good place to start
Sharpening kernel see wiki and this