Every now and then, requests for simulating different spectra than the default visible light pop up, notably thermal imaging. I implemented a quick hack for simulating thermal cameras as described here on ROS Answers and available in hector_gazebo_thermal_camera, but that clearly only works for some scenarios. This ticket is for discussion and tracking any effort towards simulating thermal cameras. I do not have the time to work on this, but maybe someone else steps in.
Issue #550 about arbitrary model properties is related to this one as implementing those could be a proper path towards thermal imaging simulation.