I was inspired after looking through the drawbots gallery on flickr, where I noticed a white-on-black vector drawing, and the lunar lander installation had used white on black colour combinations. I thought they looked really eye-catching, but I hadn't seen any 'regular' polargraph images attempted. I took the steps below and the results look fairly promising.

1. Get source image, and convert to grayscale, increasing contrast as necessary.

2. In photoshop, invert the image, making the white parts of the picture dark, and vice versa.

3. Plot on the polargraph using a white Gel pen on a black paper.

The results are nice - It's a small print, and I doubled the print at grid size 12 and 7 starting at different corner points. You still have to be a fair distance away to resolve the image, but I'll try again and plot a larger image with more range of contrast. (The starting image was very orange)

I'm presuming this will also work with the gold and silver gel pens just as well?

These drawings onto brown paper look really great. That's a good mix of subject matter, technique and material. But why do you think that line sorting, colour detection, pausing and restarting wouldn't be hard to implement? A queue of commands could incorporate a new command that causes an indefinite pause, but how would you restart it?

The solution is to use your SVG generation tool to layout separations, so you'd have your "fill" paths (white lines). Load the whites into the controller app, generate the commands and draw out your lines. Then change the pen, load your outlines (black lines), generate the commands and draw _those_ lines.

A second is to just use the "pause" button on the touchscreen to pause the motors, but you'll have to keep your eyes open and recognise when the lines are about to change!

sn

Put a frame around both source SVGs so they have the exact same outside dimensions - they'll align ok that way.

I had shied away from putting commands for the _controller_ itself into the command queue... I smell a bit of an opportunity for complexity there, but... why not!

sn

Looking good!