Dan Moore:: Drawing App & ofxMH871

The MH871-MKII Pen Plotter and Vinyl Cutter is an affordable Plotter/Cutter.  The MH871-MKII uses the HPGL (Hewlett-Packard Graphics Language) standard to drive the print head.MH871-MKII uses a limited subset of the HPGL standard:

  1. Initialize – IN;
  2. Pen Up command – PU
  3. Pen Down command – PD
  4. Pen Absolute to an X,Y point – PAX,Y

Using this knowledge I created an openFrameworks addon to directly drive the plotter from an openFrameworks application.  The openFrameworks addon can be found on my github page.


For my drawing app I created an application to generate drawings from images and draw them using the pen plotter.   I experimented with several openCV features to extract lines and contours from images.  My final app utilized coherent line drawing (CLD) and simple thresholding + blob detection to generate self portraits and portraits of others.  I combined several dithering and halftoning techniques to give the drawings more texture and depth.