Method and system for detecting elliptical objects
US4618989A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jan 19, 1984 |
| Grant date | Oct 21, 1986 |
| Priority date | — |
| Expiry date | Jan 19, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06V10/48
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In order to define the contour of an ellipse, it is necessary to determine five unknown parameters in the general equation representative of centered conics. When directly applying Hough transformation method to the above equation, since a five-dimensional space is required, it is practically impossible to detect an ellipse because a long processing time and a great amount of memory capacity are inevitably required. To overcome these problems, the geometric properties of an ellipse are determined separately on three parameter sub-spaces obtained on the basis of edge vector field: two-dimensional center histogram and two-dimensional (H, B) histogram, one-dimensional C histogram. A peak value on the center histogram represents a group of ellipse having the same center locations; a peak value on the (H, B) histogram represents a group of concentric ellipse having the same eccentricity and axis slope; a peak value on the C histogram defines a single ellipse. By sequentially selecting these peaks in the three sub-spaces, it is possible to define geometric properties of an ellipse under practical processing conditions. In order to define a plurality of ellipses efficiently, several novel…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.