| 摘要 |
<p>A target (10) for providing coded data readable by an imaging apparatus (30). Location marking means (20) enable location of the target by the imaging apparatus preparatory to an imaging operation, the location marking means having high visibility characteristics e.g. being of retroreflective material (11) to enable identification of the location marking means against a background. Code marking regions (13c-14c) of annular shape include circumferentially disposed code markings (12) containing coded data which are imaged by the imaging apparatus to enable recovery of the coded data from the target. The location marking means (20) is located generally centrally of the code marking regions (13a-14c) so that identification of the location marking means also locates the centre of the code marking regions. The location marking means (20) includes at least one concentric annular region (22) to enable fine location of the centre. The code marking regions (13a-14c) are rotationally dispersed relative to the centre.</p> |
