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Smile for the robot's camera

Tired of those shoe boxes full of bad snapshots, where half the people have their heads chopped out of the picture?

Meet Lewis, the world's first robotic photographer, a machine that may take pictures better than you do.

The 300-pound, trash-can-sized robot rolls around a room, detects faces and takes photographs based on classic composition rules. Lewis debuted last month at a conference in St. Louis.

"You can think of it as a computer on wheels," said Bill Smart, an assistant professor in computer science at Washington University. He created the robot with his wife, Cindy Grimm, a fellow assistant professor in the department.

Lewis moved slowly and haltingly through the crowd of about 90 scientists and science writers at a reception at the Ritz-Carlton Hotel. It didn't really need the name tag its handlers had attached to it.

It snapped pictures of the partygoers, drinks in hand, and of other photographers who were there to shoot it. Snapshots were taped to the wall for the scientists to review.

"It looked like it did a pretty good job," said Michael Smith, a nuclear astrophysicist at Oak Ridge National Laboratory in Tennessee. "I've botched enough pictures in my day that I know it's easy to do."

Smart and Grimm didn't set out to build the perfect automated photographer. The project was simply a good way to meld Grimm's work in modeling and computer graphics with Smart's research in robotic navigation and artificial intelligence.

Taking photographs gives Lewis a fun, practical task that captures the imagination of students and the public, Grimm said. "You don't have to have a deep technical understanding of what we're doing. You say, "Oh, it's a wedding photographer,' " Smart said.

The project cost about $70,000. Undergraduate students programmed the robot at Washington University's Media and Machines lab.

Lewis is the latest example of a robot designed to perform everyday tasks. Robotic lawn mowers and vacuum cleaners do household dirty work; robotic dusters are on the way.

"The technology is durable and fast enough now that it's a good time to be working in robotics," Smart said.

"Robotics now is like the car industry at the turn of the century. Soon we're going to get into mass robotics, and it's going to revolutionize the whole field."

Lewis was named for Meriwether Lewis of Lewis and Clark fame because of its propensity to roam as a photographer. It looks like a red trash can with two cameras mounted on top. Four car batteries and two Pentium processors power the robot, which stands about 4 feet tall.

Lewis uses laser range finders to move around a room without bumping into anything. One camera lens scans the room for skin-toned patches _ regardless of race _ about the size of a face. Lewis tries to confirm that the face belongs to a body by checking to see if an object _ presumed to be legs _ is standing beneath it.

Lewis then frames the picture according to composition's rule of thirds. If the picture was folded into thirds both horizontally and vertically, the faces should be where the lines intersect. A second camera snaps the image.

It doesn't always work perfectly. At a computer graphics conference in San Antonio this summer, Lewis "took a lot of pictures of a red poster hanging from the ceiling," Smart said.

But Lewis did pretty well overall, Smart said. The robot took 5,000 pictures at the conference and beamed them to computers nearby where participants could scroll through the images. About 2,000 of the pictures were good enough to be printed or e-mailed home, Grimm said.