Darkvision in D&D and GURPS, or How does Infravision work?

 Darkvision in D&D and GURPS, or How does Infravision work?

There is one ability that is present on most monster statblocks in D&D – darkvision. In my opinion, it is overused, as often there is even no justification for why would the creature in question ever need darkvision. For example, let’s check D&D 3.5 Monster Manual – I counted 377 monsters total, and do you know how many of them have darkvision? 239! That’s roughly 63% of all monsters. And you should keep in mind that the first Monster Manual contains many mundane animals, so for the other Monster Manuals this percentage is probably higher. But anyway, it seems to me that darkvision in D&D is not a special quality – the lack of darkvision is a special quality.

 

On one hand, I understand why there’s so much darkvision. It’s Dungeons and Dragons, after all, and most of the action transpires in the titular dungeons where usually there isn’t much light. If the only light the monsters would be able to see is light brought in by the adventurers, then they wouldn’t be able to survive on their own, obviously. From the standpoint of the player characters, light sources in D&D quickly stop being a problem. Even if your race does not have darkvision, you probably have to manage torches and sunrods on the first couple of levels – after that you are expected to find magic items, and most of them glow like torches. You probably remember that people used to call high-level adventurers Christmas trees.

 

On the other hand, it feels both gamey and lazy. In some cases, there is no justification for why a creature would even need darkvision. For example, the Pegasus – why does it need to be able to see in the dark? Or an angel who lives on the bright Upper Planes? The answer is simple – they need to be able to see in the dark so they do not get neutralized by a low-level darkness spell. Things like that make the game world less believable, in my opinion. Another thing I do not like about darkvision is that it is very difficult to interact with. The creature either has it or it does not. Sure, there are some rare alchemical items, such as ink that can only be seen with darkvision, but pretty much all alchemical items in D&D suffer from the same problem that I outlined earlier – the vast majority of them become useless after the first couple of levels.

 

All right, I got it off my chest, but let’s make it GURPS-related. How does darkvision work in GURPS? This is a trick question, because darkvision in D&D has undergone many changes across the years. While in Chainmail, D&D 3.0 and later editions it works closer to the Dark Vision advantage in GURPS with some additional minor nuances, OD&D and AD&D had infravision in place of darkvision. But even D&D infravision doesn’t work the same in all editions, and it doesn’t work like GURPS Infravision.

                When I was just starting out with GURPS, I used the Dark Vision advantage to represent D&D darkvision, but now most of the times I prefer to use Infravision. Dark Vision costs 25 points, and Infravision costs only 10 points, which makes racial templates significantly cheaper. I feel that Infravision is a much more nuanced advantage that can be interacted with in different ways. It creates interesting tactical situations for both the GMs and the players. However, there are some problems. First, there are three different Infravision advantages in GURPS. Second, GURPS doesn’t do a good job explaining how infravision works. This had been bothering me for a while, and once upon a time when browsing through my collection of Dragon Magazine pdfs, I found a very interesting article – Sight in the Darkness from Dragon Magazine #211. It describes how infravision works and all the implications of relying on infravision underground or on the surface. I found that article to be immensely useful in GURPS as well – I highly recommend giving it a read.

 

In GURPS, Infravision (p. B60) can be an advantage, allowing you to switch between normal vision or infravision, or just a feature, in which case you can only see in the infrared spectrum. First of all, this allows you to fight in complete darkness, but only against enemies that emit heat (this includes all living beings and most machines). Undead creatures and creatures with Supernatural Features (No Body Heat) will probably be in thermal equilibrium with the surroundings. According to GURPS Underground Adventures, most underground environments are in thermal equilibrium, so seeing most inanimate objects is at -2 because of low contrast, and I assume that undead beings fit right in - you will be able to fight them at -2. Also, aren't Cold-Blooded being always (more or less, at least) at the ambient temperature? They should not stand out and be at -2 to detect and fight too. Human beings and other heat sources often stand out: +10 to Vision rolls to detect them. In more normal conditions, such as outdoors during the day, this bonus is only +2. Infravision also gives you +3 to Tracking, if the trail is no more than an hour old. Also, infravision has low resolution - roll at -4 to distinguish details, such as faces or text read via reflected light. Sudden bursts of heat, such as explosions or infrared lasers may blind you. And you cannot see color.

Infrared light is reflected by most objects, so it can be used to navigate and detect everything. Realistically, you'd need very large eyes and a way to insulate them from your own body heat to use Infravision, but this is not a concern. Aboveground, objects such as large rocks usually are hotter than grass or leaves that lose their heat due to the wind, so rocks will be "brighter" to Infravision and will retain some of the glow at night. As the night falls, a character with Infravision will be able to see normally, as the terrain will radiate heat. As was mentioned, rocks will be brighter than trees and ground. While water is usually colder than the rest of the environment, it also loses heat more slowly, making it "glow" in the dark. Air is assumed to be invisible, unless very hot. Worn and wielded objects in contact with living beings will radiate some heat, and footprints, physical hits, and other friction-related phenomena leave heat marks. This is probably what gives you +3 to Tracking.

Fires emit a lot of heat, making it impossible, for example, to see a living being in front of a bonfire. I can imagine that there would be situations where you would need to know how far this blinding halo extends. I think it would be fair to invert the combat and vision penalties for heat-based light sources within their radius of illumination and halve the inverted values, rounding down, for a radius three times larger than primary illumination radius. For example, a torch illuminates a 2-yard radius, dropping the darkness penalties to -3. For an Infravision-using character, this would be -7 within that 2-yard radius and -3 within 6 yards. I'm not sure how to treat blinding effects of a fire-based attack (or an infrared laser), but I suggest the following - make an HT roll at -1 per full die of burning damage, and at +1 per yard of distance to the attack (any point along its path). If you fail, you get a penalty to Infravision-based tasks, including combat, equal to the margin of failure for margin of failure seconds. If you fail by 5 or more or fail critically, you are blinded for margin of failure seconds instead.

You should also remember that Infravision can detect the lack of heat. Thus, ice, snow, white dragons, and other cold-producing creatures would look very "dark". Also, apparently glass is impenetrable to infrared light, appearing like a mirror to those with Infravision. That's interesting.

So, when I convert D&D races and creatures, I usually represent darkvision with Infravision and, if the creature has light sensitivity or light blindness, Night Vision 5 (or more) as a feature. I often thought that this light sensitivity does not really impair them enough, that Infravision is a very good advantage to negate the darkness penalties, but after reading that article, I realized that it seems fair. For example, a drow would be able to live in the Underdark, mainly relying on Infravision. However, he would need to take extra time and risk when interacting with others, because it is very difficult to distinguish not only one drow from another, but a drow from, for example, an orc. I can imagine them using normal dim lights in places of social gathering and libraries. What about fighting an invader from the surface who is wielding a torch? They would be able to barely see and fight them off using Infravision, but they would still be penalized if they decide to switch to normal vision. Same thing for aboveground raids – there are some ways to foil infravision that would no doubt be known by the surface dwellers (because Infravision is very common in D&D worlds). And you will not even be able to look up, because the sun is absolutely blinding to Infravision! I guess that's why it is only 10 points compared to Dark Vision that costs 25 points.

Speaking of foiling Infravision. First, you can mask yourself with a heat source - sure you will stand out very obviously, but seeing any details will be almost impossible. Second, characters with Stealth might want to hide or sneak behind/in front of heat sources, such as fires, fresh piles of bodies, hot rocks, and avoid "cool spots". Third, one can just hide under a thick blanket as not to stand out against the background - but this is a temporary measure, as it will get warm in, let's say five minutes. A gelatinous cube might look like a black wall. Glass spells can create impenetrable barriers, and fire spells cause blindness or mask heat signatures. Covering yourself in mud or clay (that probably takes at least a minute) should also prevent you from standing out to creatures with Infravision. Spells, such as Cool, Warmth, Frost, Snow, can all affect Infravision. Get creative!

If you'd like to get tricky, you may adapt the rules for Light Adaptation (GURPS Tactical Shooting, p. 18) when switching between Infravision and normal vision.

Near Infrared Vision (GURPS Powers: Enhanced Senses, p. 8) works with frequencies close to the visible ones, improving resolution - there's no penalty to see facial features or print. However, living creatures do not radiate in this band and can only be seen by reflected near infrared light from the sun, very hot objects, or technological sources, such as active IR. Fire at 350°F emits a dull glow or a bright one at 1,350°F. When you have such sources, you gain the same benefits as from Ultravision (basically, +2 to Vision). You can also ignore up to two levels of Obscure (Vision) or equivalent penalties from natural conditions, such as murky water. You are blind in total darkness! Some fish have this trait.

Thermal Infrared Vision (GURPS Powers: Enhanced Senses, p. 8) doesn't actually require eyes, as it uses specialized organs. It works with longer wavelengths, including those emitted by living creatures. Resolution is too poor to read by reflected infrared. You detect warm-blooded creatures, or objects hotter or colder than the background, at ‑1 to your Sense (not Vision!) roll per yard of range. You can’t see color and have only a vague sense of shape, but you fight at no penalty even in total darkness against a target you can detect. You gain +2 to Vision to spot any such target, and +3 to Tracking for a trail no more than an hour old, but you are at ‑4 to Vision to distinguish similar objects. This is a trait that can be found naturally in some cold-blooded animals, such as snakes, and some bats.