how to get the data of hidden-surfaces ????

I use depth test to complete the hidden-lines and hidden-surfaces removal.Now I want to get the data of hidden-lines and hidden-surfaces from the depth_buffer.such as the information of vertexs , color ,etc.
Is there any good advice??

There is no information about the vertices in the depthbuffer, the depth buffer is just a 2 dimensional array of depth values nothing more.