Saturday, August 9, 2008

dappled designs

image courtesy Edward Tufte

As sunlight passes through the crown of a tree, every small opening in the crown serves as the aperture of a pinhole camera that casts an image of the sun on the ground. These sun images vary in size and brightness and may overlap, forming shadows of intricate detail and rich intensity gradations.

Artists call this dappled light. As the sun makes its way across the sky, the shapes change relatively quickly (a property of the moiré phenomenon).

If we could carefully design a tree-shaped sculpture with precisely positioned twigs and leaves, we could make a sundial that marks the passage of times and seasons by casting intricately detailed transient shadow images. For example, a tree sculpture installation that casts shadow portraits of persons whose birthday it is on that day — every day of the year, at a specific time.

Wooden shadow mirror

The artist Danny Rozin has created "mirrors" that create shadow images of the viewer by actuating simple elements such as blocks or pegs.

Tuesday, July 8, 2008

looking for the right shadow renderer...

So far, I have done most of my modeling in Matlab and IDL, but for complex 3D scenes, I need a flexible 3D renderer that would allow me to create intricate 3D detail and cast realistic shadows.

As I am fairly comfortable with C++, I am drawn to one of the incarnations of Open Inventor, although it may be overkill. Any other suggestions?

Sunday, May 18, 2008

mesh-and-shadow sculptures

Randy Cooper uses copper mesh as his medium. The resulting figures appear somewhat like three-dimensional pencil drawings. Furthermore, the sculptures cast wispy shadows that often complement the overall composition.

Meshes are also an ideal medium for moiré synthesis. The moirés in this photo are probably an artifact of digital photography. However, the sculptures themselves can generate rich moiré patterns by interfering with themselves or their own shadows. The moirés could make the figures appear to move and shimmer as the viewer moves past them. Or, with a fair amount of craftsmanship, meaningful secret moiré patterns could be integrated in these figures visible only from a specific vantage point.

shadows on curved surfaces

Originally uploaded by alwasaga
Another interesting property of shadow sculptures that can be exploited in computer-aided sculpting to enhance the visual surprise is that shadow shapes depend on the geometry of the surface onto which they are cast and the viewing angle.

I liked the artistic touch: the book appears to be a dictionary opened on imaginary and imagination.

In this piece by Kumi Yamashita titled Landscape, the shadow is cast by a straight edge and the shadow is shaped by the surface.

shadows with multiple meanings (simplest)

Another interesting property of shadows is that their meaning can change as the light source moves, even without resorting to moiré patterns, as in this sculpture by Markuz Raetz.

... or in this God-Ego duality shadow sculpture by Fred Eerdekens.

With the introduction of moiré effects, the number of possible distinct meaningful shadows can quickly multiply. So far, I have not seen anyone trying this medium.

Saturday, May 17, 2008

Monstein moiré

I have just posted this video of a moiré pattern I described in an earlier post.



The two gratings encrypt the images of Albert Einstein and Mona Lisa, hence Monstein. I made the gratings in different colors from the opposite sides of the color wheel. Google compresses videos when you submit them, so this animation does not let you see very well how the green and purple lines overlap.