Other Forms of Sight (DMG)

If the optional definition of infravision is used, the DM has set a precedent for using scientific laws to explain the ability. Some people, arguing that there are visual organs that can apparently see into the infrared spectrum (using infravision), will also argue for other forms of sight able to see into other ranges of the spectrum. These can be included, if the DM desires. However, before adding these to his game, the DM had best have a firm grasp of the rules and, maybe, of physics.
For example, just what would a character or creature with ultravision (the ability to see into the ultraviolet spectrum) see? Our eyes see objects because of visible light that is reflected off objects (except for a few objects, such as the sun, light bulbs, fires, etc., that emit enough visible light for us to see them). Infravision utilizes heat (infrared) energy emitted by objects, since almost everything emits infrared energy. The problem with infravision is that many objects, such as normal weapons and rocks, without internal heat sources, are at or very near the temperature of their surrounding and thus are nearly indistinguishable from those surroundings when using infravision. Ultravision (and vision utilizing x-rays, gamma rays, or radio waves) is useless since only stars and a few other celestial objects emit significant amounts of energy in these regions of the electromagnetic spectrum. All wold appear uniformly black with these forms of vision, except for a few objects in the sky.