Omnidirectional Vision

Image Capture Equipment

Catadioptric sensors use a rotationally symmetrical mirror viewed along its central (rotation) axis by a camera. The catadioptric sensor consisting of a conical mirror and an ordinary perspective camera has the following advantages:

It is simple to set up and operate. The equipment is relatively inexpensive and the cameras are widely available.
The projection is the same regardless of its direction (isotropic).
It captures the entire scene in a single instant, making it well suited to analysis of dynamic environments and/or moving cameras.
The image resolution and distortion of the cone mirror are favourable in comparison with other shapes of catadioptric mirrors.

We are also using true fisheye lenses (field of view of at least 180 degrees wide, i.e. hemispherical), see the front page.

Omnidirectional Sensor	Image Registration	Isotropic	Dynamic	Image Resolution	Notes
Rotating camera	mechanical problems	only for the single central column of pixels perpendicular to the rotation	no, time delay	high when all columns are used	no good for dynamic scenes
Regular polyhedrons of mirrors and several cameras	complicated	no, combinations of mirrors are not circularly symmetrical	yes, when cameras are synchronised	medium	too many cameras
Catadioptric	ok, especially with single viewpoint	yes	yes	low	easily obstructed, potential mirror support and mirror registration problems
True fisheye	easy but the lens needs calibration/correction	yes	yes	very low at the periphery, medium to high in the centre	unobstructed hemispherical view

Computer Vision Science Research Projects

Designed and maintained by Dr Libor Spacek, 13th June 2009