Directed energy deposition (DED) is a very promising additive manufacturing technique for the fabrication of sizable key components. DED offers a wide range of advantages namely a high level of formability in the manufacture of complex features, which can meet the demands of large-scale parts and be suitable for rapid manufacturing [1–3]. Consequently, DED has witnessed a rapid growth in many industries including automotive, aerospace, biomedical, and energy [4–6]. The metal powder is melted by high-energy laser beam to the surface of the substrate to form a molten pool with high temperature, high brightness, small size and fast change rate. Everton et al. [7] have proved that the formation of the melt pool helped to determine the grain growth in the solidification microstructure and was one of the main factors determining the surface quality of the coating, so the monitoring of the melt pool state is crucial [8–10]. The monitoring of the temperature distribution and geometry of the melt pool has become a hot topic in recent years. A process-mapping controlling melt pool size in laser-powder was developed by Vasinonta et al. [11], and the impact of building aspect ratio was explored. He et al. [12] recorded the geometrical characteristics of a Ti6Al4V melt cell based on the parameters of laser power and scanning speed. Yeung et al. [13] proposed the interpreter which utilized sophisticated LPBF laser control commands to improve dimensional accuracy and consistency of part quality.