| 摘要 |
This invention discloses marker detectable by visual means comprising; a polygonal border having of at least four non collinear salient points. The marker has on it a pattern in binary digital code. The binary code data contains information data, checksum and error correction. The binary code data is on two levels; a first level of binary code readable at a first given distance, a second level of binary code readable at a second given distance, where the second given distance is less than the first given distance and the second level binary code is smaller in size than the first level binary code. The second level of binary code does not interfere with the reading of the first level binary code. It also discloses a method for detecting a marker comprising the steps of detecting an image, using an edge detector to detect an edge in said image, grouping more than one edge into a polygon having salient points, calculating homography from polygon salient points, generating a list of homographies, extracting binary data from input image having homographies, identifying and verifying binary data. |
