The present disclosure is directed to devices and methods for synchronizing capturing of spectral images with the capturing of thermal images. A thermal imaging device of an aerial vehicle captures a sequence of thermal image of thermal images. Capturing of spectral images by a spectral imaging device of the aerial vehicle is synchronized with the capturing of the thermal images. Irradiance data indicative of a background temperature is sensed. A digital surface model of an area of interest is generated based on the sequence of spectral images. An emissivity of a target is estimated and a temperature of a pixel of the digital surface model of the target is estimated based on the sequence of thermal images, the irradiance data indicative of the background temperature and the estimated emissivity of the target.