Improper thermal camera operation in smoke.

[profdc9]

Describe the bug

Thermal cameras are used to image through smoke because the longer wavelength of infrared light is scattered less by small smoke particles. This is practically used by firefighters when entering smoky areas. Currently, the thermal camera (in the game "pair of infrared goggles") in CDDA does not see through smoke unlike their real counterparts. The scattering of small particles is called Rayleigh Scattering:

https://en.wikipedia.org/wiki/Rayleigh_scattering

The amount scattered varies with the fourth power of the wavelength, and so if the wavelength is halved, the scattering is reduced by 1/16. Since visible light has a wavelength of 0.4 to 0.8 micrometers, and thermal infrared sees 8 to 12 micrometers, there should be a reduction in scattering by a factor of 10,000 or more.

Attach save file

N/A

Steps to reproduce

In the collapsed tower with the "Gangrenous crawler", when a crawler is killed there is smoke released, if one is viewing with infrared goggles, one can not see through the smoke / poison gas released by the death of the Gangrenous crawler. It is not certain if this smoke is intended to be like other types of smoke, that is, composed of tiny scattering particles that scatter visible light, but scatter infrared light less.

Expected behavior

Smoke should not prevent viewing through thermal goggles, unless the smoke particles are on the order of the size of the wavelength of light, 8 to 12 micrometers.

Screenshots

No response

Versions and configuration

Linux, CDDA version 0.g

Additional context

No response

[PatrikLundell]

Thermal goggles are also useless against smoker zombies.

This issue has been discussed before, but that (those?) report is probably killed off by the stale-bot. In the previous discussion it was mentioned that modern military smoke generators provide opacity agaist IR as well as optical light. However, I failed to see any convincing argument for why zombies (and other monsters) should produce military grade smoke.

[epsimpson]

If the smoke is hot you won't see through it. If the smoke is cold you won't see through it. Why? Because scattering is only one part of EM transmission equations.

Smoke doesn't last long in cdda. By the time it equilibrates thermally, it's gone.

[github-actions[bot]]

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