Ways for Monsters to See in the Dark

[ericthered]

I'm working on a setting/scenario where Modern-Day Folks delve into a Dungeon Fantasy style under-dark. I'm looking into what sorts of vision the monsters and local inhabitants might be using down there, and I'm trying to go beyond just "magic vision". Thoughts so far:

• Echolocation sounds really neat, and I'm leaning towards tying my goblins thematically to bats.
• Infravision seems to have the downside that it doesn't allow you to see the tunnels, and while being able to freely target in combat is nice, its also nice to see stalactites hanging at face level. Am I reading this wrong, or would cave walls be visible?
• Feeling your way through seems possible, but I'm not sure. Would four foot antanna be enough to give vibration sense? Is vibration sense a good solution for an intelligent civilization that lives in the dark.
• Magical senses sound fun, though I think making them specific to things other than "what light would hit" sounds fun. The ability to detect where air is, turned into a scanning sense, for instance?

What are some varied ways to see in the dark to populate my underdark with?

[Varyon]

Vibrissae are useful for this, and are statted out on page 22 of Powers: Enhanced Senses as Sensory Hairs. Air currents can tell you a lot about the layout of an area, as well as anything moving through it, and you can directly perceive your immediate surroundings by moving your vibrissae over it. Ideally, you'll want another sense to help with hunting, but Sensory Hairs alone should be enough to navigate. Note that, statwise, they're basically just represented by Vibration Sense (Air).

An interesting option for intelligent creatures that have infravision is to create light by burning something that produces very little light in the visible spectrum, but plenty in infrared. Alcohols will do so, and while they won't last as long as oil lamps, I think ethanol lamps have decent longevity (as would, I expect, methanol lamps, which produce even less light in the visible spectrum). You could also posit some sort of fantastic fuel with similar properties but greater longevity (Essential Ethanol, although most of that ends up consumed by dwarves). Generally the humans will be able to see it in the dark, but only as a rather weak light - perhaps humans would be at -6 when the natives can see as well as humans see in daylight. As a bonus, if the humans do bring their own light sources, it will make the flames of the native's light sources functionally invisible, potentially resulting in a hapless adventurer walking right into a raging fire (although unless they're rather distracted, they'll probably notice the heat before they get dangerously close; smaller heat sources will actually be more dangerous, as you may not notice them until your hand has already gotten a bit crispy). You could also posit bioluminescent fungus that luminesces primarily or entirely in the infrared spectrum.

[Refplace]

Infravision would spot cave walls as they are going to be a different temp than the air. But you wont get much detail.
Vibration Sense is exceptionally useful below ground as your likely to have less wind.

[thrash]

Night Vision, while it does not work in total darkness, would enhance the effectiveness of any vision-based system.

Discriminatory Smell works well as an adjunct to vibratory senses.

if Dark Vision is too vague for you, you could refine the definition. For example, "Mana Sense" might allow vision based on mana levels, with mages, magic items, and other concentrations of mana standing out against the background -- especially useful for manavores, and for identifying the latent talents among the PCs. No Mana areas would be totally dark; Very High Mana areas would be blinding. "Clairvoyance" might allow a creature to simply "know" where everything is, similar to echolocation but not blocked by line-of-sight (with suitable enhancement to the point cost).

[Apollonian]

Originally Posted by ericthered

What are some varied ways to see in the dark to populate my underdark with?

Electroreception or psionic senses (Sense Minds) would be good for predators seeking prey, though they would probably have additional senses for navigating their environment.

[Shuckster]

Since vision is merely Detect (Visible Light, occasional) with the Precise, Restricted Arc and Analyzing modifiers (see "Compound eyes on page 26 of template toolkit II races) just replace visible light with anything you want and make it vison based, you might have a creature "see" the souls of beings, living or otherwise rather than see what's actually there, or be able to detect sapient minds and track them via seeing there thoughtforms.
I like the idea of using detect in such a way that the creature can see in the dark but might not be able to see everything, such as being able to detect living creatures but not unliving inorganic mater etc.

Active Electroreception is a form of vibration sense found on page 44 of template toolkit races that's [10] points. You can add (Cosmic: works both in and out of water +50%, Precise +100%) modifiers to make it function as good as vision.
Living things omits slight electromagnetic radiation and creatures like sharks, eels and even the platypus use these senses in water to detect prey and navigate dark or murky water.

Scanning Sense (Para-radar, Precise +100%) [80]
This is a more generic one but it always dose in a pinch.

You could also have the creature use a magical item or ritual that could be stolen or disrupted.

[whswhs]

Could they have Blind Fighting skill, perhaps in an instinctive version? Or could they have Dark Vision with the Hypersensory modifier (see GURPS Powers or GURPS Powers: Enhanced Senses)?

You might consider allowing a low-resolution sonar capability based on human-audible sound (clicking your tongue or tapping a stick on the ground) as a perk. It wouldn't spot things much smaller than a foot, but that would avoid most obstacles.

GURPS Underground Adventures offers the Cane Travel technique. A monster with Feelers (written up in Enhanced Senses) might be able to use this instinctively.

[The Colonel]

I like the idea of the undead using a sight that operates predominately by the "light" of souls and similar spiritual entities - pretty much the whole of the living world is thus dark, but a mortal soul stands out for miles.

[ericthered]

Thank you for all your responses, its some really good input. I'll try to respond to everyone here.

You've recommended stuff from Underground Adventures, Enhanced Senses, and Template Toolkits: Races. Apparently I need to read my Stoddard more!

Originally Posted by Refplace

Infravision would spot cave walls as they are going to be a different temp than the air. But you wont get much detail.
Vibration Sense is exceptionally useful below ground as your likely to have less wind.

Digging deeper into the recommended books, it looks like underground generally gives -2 to heat-vision... which isn't bad, all things considered. I could give night vision 2 to cancel that out if its really needed. I'm still curious why we don't see heat vision in nature if it works in the dark that well.... other than for snakes targeting warm-blooded creatures, which is a very different context.

It might be fun to vary that -2 in different locations to create some "lighting" effects.

Originally Posted by Varyon

An interesting option for intelligent creatures that have infravision is to create light by burning something that produces very little light in the visible spectrum, but plenty in infrared...

That is a nice technological trick. Light up your world! Thanks for pointing out that ethanol will do the trick.

Originally Posted by thrash

Night Vision, while it does not work in total darkness, would enhance the effectiveness of any vision-based system.

this is quite true. I'm still on the fence how much I want to use proper vision, but I might have a civilized species that just embraces using light and the consequent lack of stealth... the echolocators have detection problems of their own. Stereotypically, this would be gnomes or dwarves or some other traditionally "friendly" race, but I might subvert that.

I do want bioluminence of some kind, and I suppose that will help a lot of critters have sight of some kind at least, for the occasions when it comes up.

Discriminatory Smell works well as an adjunct to vibratory senses.

That's a really common combination in nature. I should probably consider it the standard baseline for monsters that aren't "people". Like giant velvet worms.

Originally Posted by whswhs

GURPS Underground Adventures offers the Cane Travel technique. A monster with Feelers (written up in Enhanced Senses) might be able to use this instinctively.

Originally Posted by Varyon

Vibrissae are useful for this, and are statted out on page 22 of Powers: Enhanced Senses as Sensory Hairs. Air currents can tell you a lot about the layout of an area, as well as anything moving through it, and you can directly perceive your immediate surroundings by moving your vibrissae over it. Ideally, you'll want another sense to help with hunting, but Sensory Hairs alone should be enough to navigate. Note that, statwise, they're basically just represented by Vibration Sense (Air).

Originally Posted by Shuckster

Active Electroreception is a form of vibration sense found on page 44 of template toolkit races that's [10] points. You can add (Cosmic: works both in and out of water +50%, Precise +100%) modifiers to make it function as good as vision.
Living things omits slight electromagnetic radiation and creatures like sharks, eels and even the platypus use these senses in water to detect prey and navigate dark or murky water.

Thank you for the references! I wasn't sure how grounded vibration sense was in existing creatures or how well it actually worked as written, but those entries help a lot. I think I'm on firmer ground for using feelers and hairs all over the place.

Originally Posted by Apollonian

Electroreception or psionic senses (Sense Minds) would be good for predators seeking prey, though they would probably have additional senses for navigating their environment.

Originally Posted by The Colonel

I like the idea of the undead using a sight that operates predominately by the "light" of souls and similar spiritual entities - pretty much the whole of the living world is thus dark, but a mortal soul stands out for miles.

Originally Posted by Shuckster

Since vision is merely Detect (Visible Light, occasional) with the Precise, Restricted Arc and Analyzing modifiers (see "Compound eyes on page 26 of template toolkit II races) just replace visible light with anything you want and make it vison based, you might have a creature "see" the souls of beings, living or otherwise rather than see what's actually there, or be able to detect sapient minds and track them via seeing there thoughtforms.

Feelers/vibration sense works well in combination with senses that zero in on food from afar. That's something good to remember. Also, a predator that's blind but can "hear" you think has a certain edge of horror to it.

Undead have a strong place in the setting and I was leaning towards them having their original senses, but having them able to see souls as well makes a lot of sense. The corporeal ones need to navigate underground, but a ghost that not only goes through walls but doesn't even notice them is interesting. Though there is also something fascinating about a corporeal undead who is as dexterous and agile as when they were alive, but can't see anything except the living. It results in some arcane and tragic behavior that just feels right for some undead. Including needing someone to lead them to the places where they can be properly dangerous.

I like the idea of using detect in such a way that the creature can see in the dark but might not be able to see everything, such as being able to detect living creatures but not unliving inorganic mater etc.

I like the idea too. Its just tricky to get the right ones that give you all the information you need.

if Dark Vision is too vague for you, you could refine the definition. For example, "Mana Sense" might allow vision based on mana levels, with mages, magic items, and other concentrations of mana standing out against the background -- especially useful for manavores, and for identifying the latent talents among the PCs. No Mana areas would be totally dark; Very High Mana areas would be blinding.

I am looking at an ecology driven by "Mana Blooms" where magical energy just shows up in an area for a while, either periodically or randomly. Sensing magic and things that interact with magic sounds useful... though I'd need to figure out how solid rock interacts with magic for that to be useful.

"Clairvoyance" might allow a creature to simply "know" where everything is, similar to echolocation but not blocked by line-of-sight (with suitable enhancement to the point cost).

As in sensing density... that might be the most useful sense to have. Might be interesting to make it active, just like echolocation. I'm looking at mages explicitly having extra senses they can use in connection with their field, and that one should show up there at least.

You could also have the creature use a magical item or ritual that could be stolen or disrupted.

It'd be a crazy civilization that lived that way... but I can see it. Especially if they're those night-vision people who must be cultivating some form of bioluminecence.

Originally Posted by whswhs

Could they have Blind Fighting skill, perhaps in an instinctive version? Or could they have Dark Vision with the Hypersensory modifier (see GURPS Powers or GURPS Powers: Enhanced Senses)?

Those are fairly similar in concept, aren't they? ... I sort of lean against it. Though doing something with the involved senses explicitly is on the table.

You might consider allowing a low-resolution sonar capability based on human-audible sound (clicking your tongue or tapping a stick on the ground) as a perk. It wouldn't spot things much smaller than a foot, but that would avoid most obstacles.

That's a useful comment. It sounds more like something one or two of the invaders would do than the original occupants, but the folks using night vision might pick it up.

[Anthony]

Originally Posted by ericthered

I'm still curious why we don't see heat vision in nature if it works in the dark that well....

It's hard to build a good biological infrared camera -- there's no commonly available biological material that can be used for lenses (water is opaque in IR) and the most sensitive options require cooled optics. Pit vipers are basically using a biological pinhole camera, and it's not a coincidence that there aren't any warm-blooded animals that have any noteworthy ability to detect infrared.