This paper presents Camera Motion Graphs, a technique to easily and efficiently generate cinematographic sequences in real-time dynamic 3D environments. A camera motion graph consists of (i) pieces of original camera trajectories attached to one or multiple targets, (ii) generated continuous transitions between camera trajectories and (iii) transitions representing cuts between camera trajectories. Pieces of original camera trajectories are built by extracting camera motions from real movies using vision-based techniques, or relying on motion capture techniques using a virtual camera system. A transformation is proposed to recompute all the camera trajectories in a normalized representation, making camera paths easily adaptable to new 3D environments through a specific retargeting technique. The camera motion graph is then constructed by sampling all pairs of camera trajectories and evaluating the possibility and quality of continuous or cut transitions. Results illustrate the simplicity of the technique, its adaptability to different 3D environments and its efficiency.