From Fri Mar 15 00:51:49 2002
Date: Fri, 15 Mar 2002 00:49:45 -0500
Subject: RI Seminar, TODAY, Hans Moravec
From: David Tolliver 

3D Grid Maps for Mobile Robot Perception

    Hans Moravec 
    Principal Research Scientist
    Robotics Institute
    School of Computer Science
    Carnegie Mellon University

Time and Place
    1305 Newell-Simon Hall
    Refreshments 3:15 pm
    Talk 3:30 pm 


Vector lists offer a compact representation of simple diagrams, and all
early computer displays drew point-to-point vectors. The size of vector
lists grows unboundedly with image complexity, however. Today, all computer
displays are raster based. A raster represents any image at all at fixed,
albeit high, cost. Rasters became compelling when computer memories grew
large enough to hold them and speeds high enough to fill them rapidly.

Most sonar-based research robots of the 1980s built 2D vector maps of their
world. Walls, doors and major obstacles were compactly represented, but maps
became unwieldy and unreliable in cluttered regions. Today most mapping
robots use 2D grids, which can represent arbitrary layouts in shades of
occupancy at fixed cost.

Recent computer speed and memory gains enable robot mapping in 3D.
Surface-based descriptions dominate, and are efficient for simple scenes,
but strained in clutter. Since 1992 we've been developing a 3D grid approach
that loves clutter. Our latest maps, with 16mm grid cells filled with
occupancy evidence weights from trinocular stereoscopy, occupy hundreds of
megabytes. 1,000 MIPS produces them in near real time. They acquire the
original scene's colors as a side effect of a learning process. Simulated
run throughs of the color grids can be mistaken for camera imagery of the
real scene. We think the technique can guide commercial robots this decade.

Speaker Biography

Hans Moravec received his degree from Stanford in 1980, but still works on
his robot mapping and navigation thesis. The maps were sparse 3D point lists
in the 1970s, coarse 2D grids in the 1980s, plain 3D grids in the 1990s and
colored 3D grids in the 2000s.