PPCT

Study

Working question: can a boring calibration sheet make pen, paper, and plotter behavior easier to compare?

The thing is a printable and plottable A4 test target. It exists to make small failures visible before they ruin a larger plot.

The current page explains the target. The study note still needs the calibration record: what the sheet reveals, which tests matter, and how it changes later plotting decisions.

PPCT is a calibration sheet for pen plotting.

The name is longer than the tool: PlotPen Characterization Target. The idea is simple. Generate an A4 SVG, plot it with a specific pen on a specific paper, then keep the result with enough notes to make the next test comparable.

Pens lie. Paper lies. Plotter settings lie in more interesting ways.

A pen that looks fine in a quick scribble can dry out on a long path, blob at every pen-down, feather on one paper and behave on another. PPCT gives those failures a place to show up. Straight lines, tight spacing, hatching, curves, long paths, repeated pen lifts. Nothing clever. Useful is enough.

The current version has two ways to use it. The command line generator makes the SVG from Python. The web generator does the same in the browser, with a live preview and download button.

There is one small trap: text. The full SVG includes labels, dates, operator names, and notes. That is fine for fineliners. With thicker pens the small text becomes a mess. The web version has a geometry-only mode for that case: print the labelled template once on a normal printer, then plot only the calibration marks on top.

That is probably the right workflow anyway. Printer does printer work. Plotter does plotter work.

The first photographed run is already useful. A purple HEMA 0.4 mm fineliner made the lines, and it formed a blob of ink in the geometry reference. Good. That is the kind of small warning this sheet is meant to catch before a longer plot gets fed into the machine.

The second photographed run is a HEMA 2 mm marker. It is blunt for this sheet. Large geometry and flow still read well. Fine text gets ugly, dense hatching turns into blocks, and the stipple area becomes more about ink load than dot placement. The note on the page says it well enough: careful, yet maybe useful.

Source: github.com/utrost/PPCT · 0.4 mm test note · 2 mm test note · Web generator: simiono.com/ppct · GitHub Pages: utrost.github.io/PPCT

See also: From Pixel to Pen, Gantry, Generative Art, Tracer, Vectorize, CityPlot, VHS