## 1 Introduction  
Due to advances in the Additive Manufacturing (AM) process, an increase in new manufacturable products and designs have entered the market at a rapid rate. AM has revolutionized manufacturing because of its ability to streamline production parts from computerized models to market, reduce waste, utilize a variety of materials for production, and print harsh complexity demands. The layer-by-layer process of producing 3D objects through computer-aided design (CAD) was developed in the 1980s and called \"rapid prototyping' [1]. It was originally intended as a means to create a specimen quickly as a prototype or basis model upon which further models would eventually develop towards a final product [2]. AM is a method currently best suited as a rapid prototyping technique due to engulfing issues of quality consistency, thermal stresses, and internal defects and distortions which cannot be seen from part surfaces [3]. Growth and demand in the AM area suggest a need to transverse AM into a mass production technique while maintaining its versatile production capabilities. Compared to traditional manufacturing processes (subtractive manufacturing, injection molding, etc. ), the AM research area is still relatively new and in need of in-depth investigation. The AM process possesses many advantages over traditional forms of manufacturing and can be a viable solution when conventional methods of manufacturing are not approachable. One major advantage AM has over traditional manufacturing methods is the use of designing and producing highly complex parts. As the complexity of parts increases, the price of manufacturing those parts with conventional methods increases in a similar fashion [4] however, this is not the case with AM. The cost to produce highly complex parts is drastically reduced when compared to conventional methods, such as AM produced jet engine manifolds [5]. In addition to reduced cost, AM processes have the potential to become fully automated. Research has demonstrated a strong desire to develop fully automated metal AM techniques with rapid modeling capabilities to reduce the potential of defects and ensure quality standards of parts is achieved [6; 7]. In [8], [PERSON] and [PERSON] highlight the ability of the metal AM process to produce complex designs including sudden overhang features (features that are perpendicular to the deposition direction or nearly horizontal features) without support material. The technique consists of re-orienting the workpiece and/or the deposition head upon every instance using higher order kinematics. The sudden overhang is identified from a CAD model and an orthogonal tool path is generated. While the variety of manufacturable products and designs has increased, Cyber Manufacturing (CM) systems have become a necessity for the success of Industry 4.0. The fourth industrial revolution merges both physical and digital technological concepts including analytics, robotics, additive manufacturing, artificial intelligence, advanced materials, natural language processing, high-performance computing, cognitive technologies, and augmented reality [9; 10]. As a result, AM has developed into a manufacturing technology fueling Industry 4.0 and in [11] a comparison of several popular processes is reviewed in detail. This interest has sparked a tremendous amount of research efforts to improve and develop new methods for monitoring and quality control of workpieces during AM building [12; 13; 14; 15; 16; 17; 18]. Manufacturing methods for AM vary in advantages and disadvantages which we direct the reader to [11] for a thorough analysis of the techniques. Directed-energy deposition (DED) is a technique where thermal energy is used to melt material during deposition [11]. During the DED operation, metal powder (or wire) is injected from the feedstock which is melted via a laser or electron beam and deposited on top of a substrate [19]. This particular method produces high-quality parts and possesses a high degree of controllable grain structure.