METHOD FOR MELT POOL MONITORING

A method of controlling a manufacturing process in which directed energy selectively melts material, forming a melt pool. The method includes: generating an image having an array of individual image elements, the image including measurement, for each image element, of two or more physical properties from the group including: color, emission frequency, and sheen, the measurements collectively indicating presence of: liquid phase, melting, or incipient melting; from the measurements, mapping a boundary of the melt pool, wherein for each of the measurements that indicate liquid phase, melting, or incipient melting, corresponding image elements are defined to be inside the boundary, and wherein for each of the measurements that do not indicate liquid phase, melting, or incipient melting, the corresponding image elements are defined to be outside of the boundary; and controlling at least one aspect of the additive manufacturing process with reference to the boundary.