Nadir Emissive Hyperspectral Measurement Operation (NEHMO)

A method for measuring spectral characteristics includes capturing spectral-spatial data that includes radiance measurements over spectrally flat, highly emissive surface portions of a sample material and heater at least two different heater temperatures for transmissive and/or emissive configurations. Temperatures of the sample material and heater are determined at the different heater temperatures for each configuration using, in each instance, radiance measurements taken after the temperatures of the heater and sample material have both stabilized. The transmissivity of the sample material is determined using the temperatures determined in the transmissive configuration and spectral-spatial data collected at selected points of interest over the sample material. The emissivity of the sample material is determined using the temperatures determined in the emissive configuration, the spectral-spatial data collected at selected points of interest over the sample material, and the transmissivity. The reflectivity of the sample material is determined using the emissivity and transmissivity.