DESCRIPTION

Point your laptop web cam (or any streaming webcam) at a piece of paper (or an actual whiteboard) and the program will stretch the writable area over the whole screen.

Video demonstrating some of the new features available here.

REQUIREMENTS

• python 3
• opencv (with the aruco module), numpy
• to use a streaming webcam URL as the camera source (see help for example), opencv must be compiled with ffmpeg or gstreamer support

USAGE

Prepare paper

For camera aspect ratio 16:9 print:

• to_print/a4_16_by_9.pdf or to_print/a4_16_by_9.svg on A4 paper
• to_print/letter_16_by_9.pdf or to_print/letter_16_by_9.svg on letter paper

For camera aspect ratio 4:3 print:

• to_print/a4_4_by_3.pdf or to_print/a4_4_by_3.svg on A4 paper
• to_print/letter_4_by_3.pdf or to_print/letter_4_by_3.svg on letter paper

The small circle marks the top left part of the page. If the aspect ratio of your web cam is different from 16:9 or you want to use paper with a different size see custom page

Setup web cam

Tilt your web cam so that all 4 ARUCO markers are in it's 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 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
• "a" - smooth the image by calculating an average of recent frames on / off
• "i" - invert image on / off
• "d" - de-noise on / off
• "l" - de-noise with colors on / off
• "w" - warp camera image to ARUCO markers on / off
• "k" - apply sharpening kernel on / off
• "f" - full screen mode / windowed mode

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