Method of sensing coded data on a surface
A method of sensing coded data on a surface is disclosed. Images of the coded data on the surface are captured using a sensor of a sensing device. The coded data is formed from tags, with each tag encoding a unique identity of a region of the surface and the position of the tag within the region. A perspective distortion of the coded data is estimated and compensated for when detecting data elements in the tags. The unique identity of the region from the images is determined, and the position of the sensing device within the region from the position of at least one tag in at least one image captured by the sensor is determined.
1. A method of sensing coded data on a surface, the method comprising the steps of:
capturing images of the coded data on the surface using a sensor of a sensing device, the coded data comprising a plurality of tags, each tag encoding a unique identity of a region of the surface and the position of the tag within the region;
estimating a perspective distortion of the coded data;
compensating for the perspective distortion when detecting data elements in the tags;
determining the unique identity of the region from the images;
determining the position of the sensing device within the region from the position of at least one tag in at least one image captured by the sensor.
2. The method according to claim 1 , comprising the further step of:
determining movement of the sensing device relative to the surface.
3. The method according to claim 2 , comprising the further step of:
communicating the unique identity of the region, the at least one position of the sensing device within the region, and movement of the sensing device relative to the surface to a computer system.
4. The method according to claim 1 , wherein each tag has four possible orientations relative to the surface and wherein each tag orientation contains one codeword placed at that orientation.
5. The method according to claim 2 , wherein the coded data further includes periodic elements, the movement being determined using at least one of the periodic elements.
6. The method according to claim 5 , comprising the further step of:
estimating a distance of the sensing device from one of the determined position or periodic element.
7. The method according to claim 1 , comprising the further step of:
sensing an orientation of the sensing device relative to the coded data.
8. The method according to claim 1 , wherein the movement includes acceleration of the sensing device relative to the region.
9. The method according to claim 8 , wherein the acceleration includes at least two substantially orthogonal components of acceleration.