Image filters and source of illumination for optical navigation upon arbitrary surfaces are selected according to analysis of correlation during navigation
US6737636B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 3, 2003 |
| Grant date | May 18, 2004 |
| Priority date | — |
| Expiry date | Jun 3, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0317
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Optical navigation upon grainy surfaces whose orientation is inclined at about 45° to the X and Y axes of the navigation mechanism is enhanced by: First, detect that a spatial filter in use is inappropriate for the orientation presently occurring, and; Second, employ a different and more appropriate spatial filter subsequent to such detection. Two spatial filters have been developed that are respectively effective about the 45° and 135° inclinations of the Standard filter. The shape of a correlation surface used in the navigation process is tested for the presence of a transverse ridge in the correlation surface. This generates control metrics whose filtered excursions are tracked by a control system that changes the spatial filter in use. The control system incorporates a time constant to prevent thrashing and excessive sensitivity to isolated random variations. The direction from which illumination arrives relative to the X and Y axes affects the range of angles (relative to, say, the Y axis) that a filter is effective, by changing the apparent size and proportions of the highlights and shadows that are the perceived features ultimately navigated upon. Stable operatio…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.