Pinhole sundials are just the sort of wonderful devices that one might find in a cathedral built during the Renaissance.
The sundial works by focussing the sun's rays into a bright spot on the church's floor. The movement of this spot marks the course of the day.
The interesting aspect here is that the shape of the spot is not simply due to the shape of the hole that it passes through. The hole is so small that it actually acts like a lens and what is displayed is really an inverted image of the sun itself. It works just like a giant pinhole camera.
This becomes more apparent when the spot is observed during a solar eclipse...
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Scientists in Sweden have developed a novel technique for making micromachines and demonstrated its potential by making a micro pinball table in which silicon cantilevers acted as the 'flippers', magnetic beads 150 microns in diameter were the balls, and the table measured 25 millimetres square.The table was tilted at an angle of 20 degrees to the horizon.
They found that the speed of a ball could reach up to 0.75 kilometres per hour - or 210 000 microns per second. This is equivalent to a football having an almost supersonic speed of 1125 km per hour (see a movie of the action).
"The pinball games are used for demonstrating this simple and easy process," says researcher Martin Bring. "It also demonstrates some of the effects that occur on the micrometer level, such as small apparent inertia."
I'm sorry but I just happen to think that this is really really cool.
Image morphing techniques can generate compelling 2D transitions between images. However, differences in object pose or viewpoint often cause unnatural distortions in image morphs that are difficult to correct manually. Using basic principles of projective geometry, this paper introduces a simple extension to image morphing that correctly handles 3D projective camera and scene transformations. The technique, called view morphing, works by prewarping two images prior to computing a morph and then postwarping the interpolated images. Because no knowledge of 3D shape is required, the technique may be applied to photographs and drawings, as well as rendered scenes. The ability to synthesize changes both in viewpoint and image structure affords a wide variety of interesting 3D effects via simple image transformations.Here is an animation of the complete rotation in 20 frames (64K MPEG). Those eyes really follow you around the room, don't they?[more]
A different side to Mona
You might also like to check out La Gioconda in 3D! This image was made by taking two adjacent frames from the animation and putting them side-by-side. You'll need to cross your eyes to get the three dimensional effect.
