Two-way semi-automatic registration in augmented reality system

Abstract

Augmented reality (AR) system is a virtual environment that overlays the computer generated graphics on real-world view. A typical AR system consists of optical motion tracking and capturing. The main problem in such a system is minimizing error of mapping the movements of the actor in real domain to the virtual model. To do that, the position of markers attached to the actor needs to be carefully selected and mapped to the virtual counterpart. This one-to-one mapping process is called registration. In this regard, virtual and real domains should be aligned correctly. Any minute error in registration of these two domains results in degrading of the realism e.g. wrongly registered objects floating through each other. Current registration method for optical motion capture systems requires time-consuming and tedious manual processing. To overcome this problem, we present two-way (virtual object to real domain and real domain to virtual object) semi-automatic registration method. With our method instead of priory determining positions of markers on the physical object, we determine markers' positions (extreme points found by our application) on the virtual object and then locate markers at the approximate positions on the real object. By tracking the markers in the following step, we get markers' positions in real domain and change virtual domain's markers' positions accordingly to reduce error. Results show that our system solves the registration problem and prevents unrealistic jittering and flickering effects due to misalignment.