In this paper, the relationship between the tilt angle and altitude of a PTZ camera and the 3D-to-2D coordinate
transformation is built. A vision-based approach is then proposed to accomplish the estimation of tilt angle and altitude
based on the observation of some simple objects lying on a horizontal plane, with known intrinsic parameters of the PTZ
camera. The patterns could be a circle, a corner with known angle, more than two corners with unknown but equal
angles, or more than two line segments with unknown but equal lengths. Furthermore, if we are given a few line
segments with known but not necessarily equal length, the estimation of tilt angle and altitude can also be achieved via
an optimization procedure. The impacts of parameter fluctuations are analyzed via computer simulations. Experimental
results on real images conform to our analysis and demonstrate the efficiency of this approach.