Locus smoothing method and navigation device using the same

A locus smoothing method, processing a current estimated displacement according to a predetermined number of previous output smoothed displacements, the locus smoothing method comprising:

• accumulating the predetermined number of previous output smoothed displacements to produce an accumulated displacement and recording a last output smoothed displacement;
• estimating a current estimated displacement;
• forming a digital filter according to the accumulated displacement, the last output smoothed displacement and the current estimated displacement;
• and
• processing the current estimated displacement with the digital filter to produce a current smoothed displacement.

A navigation device, which performs locus smoothing with a digital filter, the navigation device comprising:

• an image sensing unit for capturing images to produce a current digitized displacement;
• a processing unit forming the digital filter according to an accumulated displacement of a predetermined number of previous output smoothed displacements, a last output smoothed displacement and the current digitized displacement, and processing the current digitized displacement with the digital filter to produce a current smoothed displacement;
• and
• a storage unit for storing the accumulated displacement, the last output smoothed displacement and the current digitized displacement.