Wednesday, July 7, 2010

2nd Day of ISUVR 2010 - Invited Talk 1

Gehard Reitmayr gives a talk, entitled 'Panoramic Mapping and Tracking on Mobile Phones'.


He mentioned about the approach connecting the model generated by SLAM and the real space (using sensors, recognition techniques..).

PanoMT is a panorama tracking method running on mobile phones in 30 fps. It uses sensor data for camera's rotations in roll and pitch, while also usingfeature tracking on images in multi-scales.
Interesting features of PanoMT are :
  • Panorama correction: Aligning false panorama esitmation by correcting the cylinderical projection.
  • Loop closing: RANSAC matching is used to register the image over 360 degrees.
Sensors are noisy and calibration is required. For example, accelerometers and compasses have transient and local disturbances and thus sensor calibration is inevitable, whereas visual tracking provides accurate pose relative to a model. Hybrid tracking using both reduces errors in sensor values


Gehard discussed using maps instead of frame to frame detectioni/tracking, which is computationally expensive, is better : reducing redundency, less data, and slow changes. Template matching with Walsh transformation and NCC is used to map the selected template and the panorama.


As a last topic, he mentioned visualization issues, called image-based ghostings. Simple overlaying of virtual objects occludes the real scenes providing many visual queues. So the question 'which information has to be presented ?' comes here.
His solution to the problem is finding out clues from the image. Through image analysis and user interactions, the ghosting becomes possible. For better perofrmance panoramic remapping is used again.



He conclude the talk with future directions of the current work: extending to 6DOF tracking, object detection to link with applications.

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