How does laser scanning work?
A. A sheet of red laser light illuminates the object, painting a thin stripe onto it. A video camera looks at the object from the side. By analyzing the changing shape of the stripe as it sweeps across the object, we can compute the shape of the object, at least as seen from one side. The resulting data takes the form of a grid of points in three-dimensional space, sometimes called a range image. By connecting neighboring points, we produce a mesh of tiny triangles. By scanning the object repeatedly from different angles, and then combining the resulting range images, we produce a new, larger triangle mesh that completely describes the object, at least to the extent we can see it from the outside. Our triangles are about 1/4 millimeter on a side, small enough to capture the chisel marks of Michelangelo. After we’ve finished recording the shape of the object, we scan it a second time, this time illuminated by white light, and we use a second camera to record the object’s color. To see w
