In three-dimensional (3-D) video coding systems, depth maps represent the geometric information of a 3-D scene. Since depth maps are not displayed to viewers but to generate virtual views, the quality of depth maps needs to be measured by its effect on the virtual view quality, which is indicated by the virtual view distortion (VVD) in depth map coding. In this letter, a fine VVD estimation method is proposed based on the analysis of the VVD. Specifically, the depth distortion of the current pixel, the texture gradient of the colocated color video and the depth distortions of adjacent pixels are all taken into consideration to estimate the VVD accurately. Experimental results demonstrate that the proposed method can improve 13.1% bitrate saving compared with the sum of squared differences based depth distortion calculation method and can improve 1.2% bitrate saving compared with the VVD estimation method in three dimensional high efficiency video coding (3D-HEVC) reference software.