A novel depth estimation and occlusion boundary recovery approach for a single outdoor image is described. This work is distinguished by three contributions. The first contribution is the introduction of a new depth estimation model, which takes the camera rotation and pitch into account, thus improving the depth estimation accuracy. The second contribution is a depth estimation algorithm, in which we classify the standing object region with visible ground-contact points into three cases according to the information of vanishing point for the first time, meanwhile, we propose the depth reference line concept for estimating the depth of the region with depth change. Two advantages can thereby be obtained: improving the depth estimation accuracy further and avoiding the occlusion mismarked phenomenon. The third contribution is the depth estimation method for the standing object region without visible ground-contact points, which takes the mean of minimum and maximum depth estimation result as region depth and prevents the missing phenomenon of occlusion boundaries. Extensive experiments show that our works are better than previously published results.