Big Wet Pixels 5 from Cassidy Curtis on Vimeo.
Bigger, wetter, more pixelated! Playing with different strategies for sub-pixel brushstroke planning. There are so many possibilities…Category Archives: video
Big Wet Pixels 3
Still exploring big wet pixels (originally inspired by the #genuary4 prompt) using my watercolor simulation in Unity. Now the pixels are actually pixels: given a random selection of pigments and paper, they try their best to match the color coming in through my webcam. Lovely glitches ensue.
To get this working, I had to go back and solve an old problem that’s bothered me for decades: given an arbitrary set of three pigments and paper, what combination of pigment densities will produce the closest match for any given RGB color? This is non-trivial, because the gamut described by three Kubelka-Munk pigments is non-linear, not necessarily convex, and might even not be an embedding! In our 1997 paper we addressed that problem in a really crude way, which I was never very happy with: quantize the pigment densities into bins, and find the nearest bin in RGB space using a 3d-tree search. So it gave me great satisfaction last weekend when I implemented a continuous solution, using gradient descent.
The curved RGB color gamut described by a trio of semi-opaque white, amber and green pigments on purple paper. The white sphere represents the RGB color we’d like to match. A smaller, colored sphere represents the closest approximation that can be produced within the color gamut. A thin, meandering line shows the path taken from the middle of the gamut via gradient descent.
Genuary 4: More Big Wet Pixels
Getting more aggressive with color and texture…
Genuary 4, 2024: Big Wet Pixels (and No Palettes)
It took me a minute to get going this year, mainly because my watercolor simulation code is a big pile of spaghetti that’s been artfully splattered across the walls and left to dry in place. I’ll have to do a bit of cleaning before I can have more serious fun with it. But I did at least manage to get my synthetic paper layer working, more or less. This video serves the prompts for both #genuary4 (Pixels) and #genuary2 (No Palettes). Happy #genuary to all who observe!
Garden Timelapse: Sugar Ann Peas
I’ve continued to shoot timelapse video of the various veggies we grow in the garden. Here’s one more from last fall, of some sugar snap peas. They grew so fast I had to shoot twice a day! I was blown away by the origami-like way each pair of leaves unfolds as the vines grow, and the branching tendrils that whip out and grab on to whatever they can find. You might also notice some sudden changes in early September: we had a brutal heat wave that almost killed the plants. Some quick thinking and an old kid-sized umbrella saved them from total destruction. Not all of the plants survived, but the ones that made it produced crunchy pods as sweet as candy. Will definitely grow these again!
“Believable Acting” video now online
ACM SIGGRAPH has posted the video of my April 12 talk about our team’s work on believable acting for autonomous animated characters. This was a really fun one to do. Most conferences limit you to 25 minutes for technical talks, but we’ve always had a lot more material than that! The San Francisco SIGGRAPH chapter’s talk format is comfortably open-ended, so I was able to spend a full hour and go a lot deeper without rushing through it, and still leave plenty of time for Q&A.
Huge thanks to Henry LaBounta and the SF SIGGRAPH organizers for inviting me, and to the audience for showing up and asking such thoughtful and interesting questions!
Homemade ink timelapse
My dear friend Eric Rodenbeck has been experimenting with creating his own homemade inks and paints from natural materials. Some of the inks mysteriously change in texture, and even color, as they dry. After months of looking at Eric’s paintings, I was intensely curious to see how these changes would look as they were happening. So, of course, I had to shoot some timelapse footage.
The inks I used here are hibiscus + lemon (pale red), hibiscus + orange peel (magenta), carrot greens + alum (yellow), and a sprinkling of sea salt for texture. Time span: about 1 hour.
If you pay close attention, something really strange happens about 11 seconds in to the video, when I added some yellow ink: wherever the yellow mixes with the magenta, the mixture turns a deep bluish green! What is going on there?
It turns out that hibiscus gets its color from a type of pigment called an anthocyanin, whose structure and color are pH-sensitive. In an acidic environment, it’s red, but when exposed to an alkaline it turns blue. Since the yellow ink is alkaline, it turns the red hibiscus blue on contact, which then mixes with the ink’s yellow pigment, becoming a lovely vibrant green.
Here are some more photos from the day. Hopefully this will be the first of many such experiments!
Impossible Paint: Asemic Writing
The Genuary prompt for day 14 is “asemic”, i.e. writing without meaning, which is something I’ve always loved. I thought it might be fun to try doing that with my watercolor simulation. Reader, I was not disappointed.
When we rerun the simulation with a different random seed each time, it comes to life in a different way. It turns out the Perlin noise that drives the brush movement isn’t affected by the seed, so “what” it writes stays the same, while “how” it’s written changes. The consistency seems to deepen the illusion of intentionality, which makes me super happy.
This isn’t my first time tinkering with procedurally generated asemic writing. That was in 1996, when I was working at PDI in Sunnyvale. There was a small group of us who were curious about algorithmic art, and we formed a short-lived club (unofficially known as “Pacific Dada Images”) that was much in the spirit of Genuary: we’d set ourselves a challenge, go off to our desks to tinker, and then meet in the screening room to share the results. The video above came from the challenge: “you have one hour to generate one minute of footage, using any of the software in PDI’s toolset”. I generated the curves in PDI’s homegrown script programming language, and rendered them using a command line tool called mp2r (which Drew Olbrich had written for me to use on Brick-a-Brac).
Impossible Paint: pigment studies 2
Now with randomized physical properties: staining, deposition, specific weight, granulation. This is starting to do things I don’t understand, which is always a good thing.
Impossible pigments for impossible paint
To make impossible paint, you need impossible pigments.