The short of it is stereovision using hyperspectral thermal cameras, but the long answer is a bit more interesting. The problem with doing stereoimaging with t

The short of it is stereovision using hyperspectral thermal cameras, but the long answer is a bit more interesting. The problem with doing stereoimaging with thermal radiation is that almost all objects are glowing due to radiation emission which blurs out the 3d texture of the object. The example they give is if you have a lighbulb with some texture, you can't see it when it's on(you might experiment with this in various 3d engines). This makes it difficult to do stereoimaging because everything is so blurry. To do this they develop a way to deconvolute the temperature, emissivity, and light reflected by the object(they call this texture). They assume that the much of the reflected light comes from a couple objects in the scene with known properties such as the sky and ground which allows them to get an estimate of surface normal and do something like inverse ray tracing to estimate the light reflected by the object. They also estimate the emissivity by comparing the spectra to a library of spectra for different materials. I think they use this as part a second step in their inverse ray tracing to work out reflected light and temperature of objects. Much of this is detailed in the supplementary information[0]. It's interesting because they have a passive sensor for depth which works at night, but also estimates what objects are made of. It may degrade when there are fires which may break some of the assumptions they make to estimate reflection or spills of IR absorbing substances. Gasoline, CO2, methane, and other gases can strongly absorb in the infrared spectrum. Which may interfere with temperature and material estimates. [0]https://www.nature.com/articles/s41586-023-06174-6#Sec24 https://www.nature.com/articles/s41586-023-06174-6#Sec24