The visible-spectrum gaze tracker (VSGT) provides better user experience than the traditional infra-ray (IR) based one. But the design challenge becomes considerably higher due to various projection shapes of the eyeball as well as illumination conditions. The accuracy/precision of the gaze tracker highly depends on the accuracy of the eyeball model and the corresponding model matching performance. In this paper, we propose a comprehensive algorithm for eyeball model construction and refine the matching equations. The experimental result shows the proposed algorithm significantly improves the overall eyeball matching performance.