Computer Vision Marker — Rendering and Recognition
Computer Vision Marker (CVMA) is a small Application Programming Interface (API) and Command-Line Interface (CLI) to render and recognize simple marker tags for Computer Vision (CV).
CVMA is a very opinionated and specialized solution, primarily intended for a special scenario only:
- CVMA is used to encode 1, 3, 5, 9, 11, 17, 20, 27 or 30 bit of payload data (usually representating an increasing page number and/or a page duration) into optical 2x2, 3x3, 4x4, 5x5 or 6x6 matrices of black/white pixels and render these matrices as marker tags in PDF or SVG format.
- These marker tags are then overlayed to the pages of a content document in order to tag the pages and let their optical occurence being automatically tracked.
- These document pages are then displayed on a tablet computer in a zoomed and shifted, but not perspectively distorted, fashion during a live-produced video session.
- During this video session the video stream of the tablet is continuously captured and the marker tags being recognized and decoded again in order to control a table of content and progress bar on a Head-Up-Display (HUD) and Teleprompter of the live video session.
The effect of this scenario is that a presenter can scroll to arbitrarily document pages on his tablet during the live video session while a CVMA-based application closely tracks the content position on the HUD and displays the amount of estimated presentation time on the Teleprompter.
PERFORMANCE NOTICE: the marker recognition currently is rather slow -- about 300-500ms. This means CVMA can only process a video stream with about 2-3 fps. For the intended scenario this is still sufficient, but for anything else it could be a real show-stopper, of course.
$ npm install -g cvma
The Unix manual pages for the API and the CLI contain detailed usage information.
FIXME
Copyright © 2020 Dr. Ralf S. Engelschall (http://engelschall.com/)
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