Radiometric measurement device

An apparatus, comprising:

• a process metrology radiometric measurement device, the radiometric measurement device comprising:
• a number n of sensors, wherein a respective sensor of the number n of sensors is configured to generate associated sensor data, such that overall a number n of sensor data is generated by way of the number n of sensors;
• a measurement variable calculation unit configured to calculate a number m of process measurement variable values depending on the number n of sensor data on the basis of values of a number d of parameters;
• and
• a learning unit, wherein the learning unit is configured to calculate the values of the number d of parameters on the basis of training data, wherein
• the radiometric measurement device self-calibrates via the learning unit, and
• at least one process measurement variable is selected from a set of process measurement variables comprising:
• filling level of a material,
• positions and/or thicknesses of individual material layers of a material,
• material density,
• conveyed mass of a material,
• mass flow rate of a material throughput.