In one example, a control process for additive manufacturing includes: forming an extent of unfused build material on a support; applying a coolant to unfused build material within the extent of unfused build material in a pattern of spots; capturing a thermal image of the extent of unfused build material with a thermal imaging device; mapping a pixel location in the thermal image to a physical location for each of multiple spots in the pattern; and based on the mapping, establishing a transform between pixels on the thermal imaging device and physical locations on the support.