Integration of
Vision and Inertial Sensing
PhD 2003 – 2007
InerVis
Integrating Inertial Sensors with Artificial Vision
Human inertial sensor: The vestibular system
key contributions:
 a common framework for inertial-vision sensor integration;
 calibration methods for integrated inertial and vision systems;
 vertical feature segmentation and 3D mapping;
 ground plane segmentation;
 3D depth map registration;
 independent motion segmentation.
 at  
ωt 

 body
 v t 
 xt 


θt 




g
t

 world
INS calcs
Within the inner ear, the vestibular system measures tilt and angular acceleration
Data From Inertial Sensors
Inertial
sensors
Match features
across images
Camera
real world
Image
processing
Images
time
Dynamic 3D(t)
reconstructured
world model
 points 
opticalflow


 lines 


 features  time 
MEMs Inertial sensors
Xsens MTi IMU
Registering Stereo Depth Maps
Analog devices
ADXL202 dual axis ±2g accelerometer.
Analog devices ADXRS150 angular rate sensor
(gyroscope). (October 2002)
Sensor Calibration
• N static poses observing vertical target
– Full camera
calibration
– IMU↔CAM Rotation estimated
Independent Motion Segmentation
• Both sensors used to measure
the vertical direction
•N observations at different
camera positions
•Unknown rotation determined
Swinging pendulum sequence
•
Background subtraction
• 2N static poses with N rotations about IMU
1)Quantise registered point cloud to voxel space and
accumulate occupancy votes for all frames
2)Threshold to obtain background voxels (apply thinning
and growing transformation for noise filtering)
3)Intersect current frame voxels with complement of
background voxels to have voxels from moving objects
– IMU↔CAM Translation estimated
Raw voxels
•
=
background voxels
Seg. motion voxels
Optical flow consistency segmentation
1)Image optical flow (LK)
Images
2)Estimate optical flow from
3D data and reconstructed
camera motion assuming static
scene
3)Subtract and threshold to
Camera
motion
segment independent
motion
Depth
Map
selected publications:





•
•
•
Jorge Lobo and Jorge Dias, "Relative Pose Calibration Between Visual and Inertial
Sensors", International Journal of Robotics Research, Special InerVis Issue, in press.
Peter Corke, Jorge Lobo and Jorge Dias, "An introduction to inertial and visual sensing",
International Journal of Robotics Research, Special InerVis Issue, in press.
Luiz G. B. Mirisola, Jorge Lobo, and Jorge Dias, "Stereo Vision 3D Map Registration for
Airships using Vision-Inertial Sensing", In The 12th IASTED Int. Conf. on Robotics and
Applications, Honolulu, USA, August 2006.
Jorge Lobo, João Filipe Ferreira and Jorge Dias, "Bioinspired Visuo-vestibular Artificial
Perception System for Independent Motion Segmentation", In Second Inernational
Cognitive Vision Workshop, ECCV 9th European Conference on Computer Vision, Graz,
Austria, May 2006.
Jorge Lobo and Jorge Dias, "Relative Pose Calibration Between Visual and Inertial
Sensors", Proceedings of the ICRA 2005 Workshop on Integration of Vision and Inertial
Sensors - 2nd InerVis, Barcelona, Spain, April 18, 2005.
Jorge Lobo, Jorge Dias , “Inertial Sensed Ego-motion for 3D Vision”, in Journal of Robotic
Systems Volume 21, Issue 1, pp. 3-12, January 2004.
Jorge Lobo and Jorge Dias, “Vision and Inertial Sensor Cooperation, Using Gravity as a
Vertical Reference”, in IEEE Transactions on Pattern Analysis and Machine Intelligence,
PAMI, 25(12), pp. 1597-1608, December 2003.
Jorge Lobo, Carlos Queiroz, Jorge Dias, “World Feature Detection and Mapping using
Stereovision and Inertial Sensors”, in Robotics and Autonomous Systems, Elsevier Science,
vol. 44, Issue 1, pp. 69–81, July 2003.
Contact Person:
Jorge Lobo
Email: [email protected]
Mobile Robotics Laboratory
Institute of Systems and Robotics
ISR – Coimbra