Handheld device and positioning method thereof

A handheld device, comprising:

• an image capturing unit configured to capture images of frames containing a reference;
• a processing unit, coupled to the image capturing unit, configured to perform a positioning method for:
• obtaining a first image position of the reference;
• computing a first pointing coordinate according to the first image position and a first tilt angle indicative of a rotation angle of the handheld device;
• computing a second pointing coordinate according to the first image position and a second tilt angle that is rendered based on a movement of the first image position of the reference;
• computing a first displacement vector between the first pointing coordinate and the second pointing coordinate, and generating a unit displacement;
• obtaining a second image position of the reference;
• computing a third pointing coordinate according to the second image position and the second tilt angle;
• and
• obtaining an output pointing coordinate according to the third pointing coordinate and the unit displacement, wherein the step of obtaining the output pointing coordinate in the positioning method further includes:
• a) setting a number of calibrations as N, a compensation vector as C and a calibration coordinate, wherein the calibration coordinate is the third pointing coordinate;
• b) determining whether the first displacement vector is greater than a predetermined threshold;
• c) setting N equal to the first displacement vector divided by C when it is determined that the first displacement vector is greater than the predetermined threshold, wherein C is a predetermined compensation value;
• setting C equal to the first displacement vector divided by N when it is determined that the first displacement vector is less than the predetermined threshold, wherein N is a predetermined number of calibrations;
• d) computing a sum of the calibration coordinate and C to generate a compensated pointing coordinate;
• e) executing N-1 and determining whether N is equal to zero;
• and
• f) setting a fourth pointing coordinate to be the calibration coordinate and returning to step d) upon determined that N is not equal to zero;
• wherein the forth pointing coordinate is computed according to an image position of the reference and the second tilt angle.