August 28, 2013
MIT 3D Mapping Algorithm Solves Pesky ‘Drift’ Problem
[ Watch The Video: Deformation-Based Loop Closure For Large-Scale Dense RGB-D SLAM ]
Lee Rannals for redOrbit.com - Your Universe Online
In the film Mission Impossible: Ghost Protocol, characters Ethan Hunt (played by Tom Cruise) and Benji Dunn (played by Simon Pegg) break into a highly secure room in the Kremlin with the help of an animated wall that mimicked their surroundings in order to make a highly secured hallway look empty. This Hollywood fantasy technology just got a step closer to reality with the latest algorithm from MIT.
Researchers have created a new mapping algorithm capable of creating a highly detailed and accurate 3D map of indoor and outdoor environments in real time. The team took a low-cost Microsoft Kinect camera down the halls and stairways of MIT's Stata Center and applied their mapping technique to the recorded video. The algorithm was able to quickly stitch images back together to help "close the loop," conquering a problem many scientists in the robotic mapping community have faced.
Previously, scientists attempting to create 3D maps have struggled with the problem commonly known as either "loop closure" or "drift." This occurs when a camera pans across a room or travels down a corridor, introducing slight errors in image alignment that add up to a shifted wall or doorway. This problem eventually leads to a disjointed map that features misplaced walls or stairways.
MIT's new mapping technique determines how to connect a map by tracking a camera's pose, or position in space, throughout its route. As a camera returns to the place where it began, the algorithm is able to determine which points within the 3D map to adjust.
“Before the map has been corrected, it’s sort of all tangled up in itself,” said Thomas Whelan, a PhD student at NUI. “We use knowledge of where the camera’s been to untangle it. The technique we developed allows you to shift the map, so it warps and bends into place.”
Whelan says that their new technique could eventually be used to help guide robots through potentially hazardous or unknown environments.
“I have this dream of making a complete model of all of MIT,” says John Leonard, a professor of mechanical engineering at MIT who is also affiliated with MIT's Computer Science and Artificial Intelligence Laboratory. “With this 3-D map, a potential applicant for the freshman class could sort of ‘swim’ through MIT like it’s a big aquarium. There’s still more work to do, but I think it’s doable.”
In Ghost Protocol, the two IMF spies used a camera attached to an iPad to create a 3D map of a hallway so that they could project it onto a screen and make it appear as though the hallway was empty. Cruise and Pegg's characters hid behind the wall and moved it forward in order to get to a doorway so they could steal a highly-secured document, all while a Russian security guard was keeping watch on an "empty hallway." While some of the technology used in this "Mission Impossible" scenario remains far-fetched, algorithms like the one created by the MIT team inch it ever closer to reality.