Blindness and Dark Vision- please help me clear it up

[Xloth]

The blindness disadvantage (Basic p. 124) says the user can't see at all. But it only mentions other visual spectra, e.g. infra(p. 60)- and ultra(p. 94)-vision. It mentions how Scanning(p. 81)- and Vibration(p. 96)- Sense are allowed but nowhere is it stated about Dark Vision (p.47).

So the real question is, how does one define the Dark Vision advantage? As sight or as something a little different.

[mlangsdorf]

What would be the mechanical effects of someone with Dark Vision and Blindness? You're blind, but you can see in the dark? That doesn't really make sense.

If you can only see in darkness, and you can't see at all in light, I'd treat that as 0 point feature (much like 0 point Infravision or Ultravision). If you also can't see colors, you also have Color Blindness.

[Anthony]

Originally Posted by Xloth

So the real question is, how does one define the Dark Vision advantage? As sight or as something a little different.

It's sight -- it's affected by visual countermeasures other than darkness. If you want dark vision that isn't sight, you buy it as scanning sense.

[evileeyore]

Originally Posted by Anthony

It's sight -- it's affected by visual countermeasures other than darkness. If you want dark vision that isn't sight, you buy it as scanning sense.

In the past (for simplicity sake) I've allowed Dark Vision [Based on Sense X, +0%].


However I'd never allow that combined with Blindness.

[Skarg]

Originally Posted by mlangsdorf

What would be the mechanical effects of someone with Dark Vision and Blindness? You're blind, but you can see in the dark? That doesn't really make sense.
...

If I read that on a character, I'd think they had Dark Vision, and then got blinded, and I'd want to know how they were blinded, since if they ever get healed or something, they'd probably then have the Dark Vision. Until/unless they are healed, though, I'd say the Dark Vision is worth practically no points and would charge no points unless it's a setting where healing the blindness is fairly easy.

It's like having great hand weapon skills but your arms are missing... in some settings, it's just a flesh wound.

[Bruno]

Originally Posted by Anthony

It's sight -- it's affected by visual countermeasures other than darkness. If you want dark vision that isn't sight, you buy it as scanning sense.

Yep. If you want to be "blind" and have Dark Vision, skip blindness and just tack colour blind on the character.

If you want a character with Dark Vision with e.g. Mana Sensitive who becomes blind when they lose Dark Vision, that looks like this:

Dark Vision (Mana Sensitive, -10%) [23]
No Blindness (Mana Sensitive, -10%) [45]
Blindness [-50]
Net cost 18 points.

If you go with the "I'm always Colour Blind, not just in the dark" version I think it breaks down like this

Dark Vision (Mana Sensitive, -10%) [23]
No Blindness (Mana Sensitive, -10%) [36]
Colourblindness [-10]
Upgrade Colourblindness to Blindness [-40]
Net cost 9 points.

This is game-mechanically different from Blindness and a Scanning Sense because Scanning Senses have a hard range limit and even Para-Radar is kinda detectable. They also come with other side-effect mechanics that make them different from "Vision but with Dark Vision".

If your character never risks the penalties of Blindness, then what they have is Dark Vision and Injury Tolerance: No Eyes.

But if the idea is a character who can "see" the surfaces of things but has no real interaction with optical properties (can't see through glass, can't read computer screens), like I've seen some interpretations of D&D Dark Vision, that's not GURPS Dark Vision. I haven't found a satisfactory way to map that - the closest is a Scanning Sense but I don't like the game mechanical differences from Vision.

I think it's really a new kind of Bad Sight, probably in the -15 to -20 points range (and can't be corrected). Combine with Dark Vision et voilla.

[Phantasm]

For the more "hard science" character whose vision is shifted so that he can only see in the dark (say, using the far ultraviolet, edging on using gamma/X/cosmic rays) and is blinded outside it, unless he has special eyewear that blocks out all of the ambient IR/visual/UV spectrum, I'd go with the following:

Dark Vision (No Normal Vision) [0]
Blindness (Mitigator: Glasses, -60%) [-20]


Edit: Okay, it's kinda rubber-sciencey, rather than true hard science, but it's more scientifically plausible, even if not really probable or even possible, as far as we know.

[Flyndaran]

Originally Posted by Bruno

...
But if the idea is a character who can "see" the surfaces of things but has no real interaction with optical properties (can't see through glass, can't read computer screens), like I've seen some interpretations of D&D Dark Vision, that's not GURPS Dark Vision. I haven't found a satisfactory way to map that - the closest is a Scanning Sense but I don't like the game mechanical differences from Vision.

I think it's really a new kind of Bad Sight, probably in the -15 to -20 points range (and can't be corrected). Combine with Dark Vision et voilla.

Sounds kind of like impossibly high definition sonar only without a detectable emitted sound.

[Dalillama]

Another option would be reversing the vision penalties, so the character sees normally in full darkness, and -10 in full light, with intermediate penalties swapped the same way. Which I would call a feature probably.

[malloyd]

The points you get for Blindness are for you can't easily navigate unfamiliar areas, recognize things at range, and always have a serious combat penalty. If those are not true, you do not have Blindness, regardless of whether you can see anything in visible light or not (though maybe you could argue it should be worth -20 points rather than the -10 for Color Blind). If you do have them, then you can be Blind despite the fact you can still tell when the sun is up.

I suppose I'd let you take both Blindness and Dark Vision if you also take Not Blind (only in the dark -20%) as an advantage. I'd actually say much the same for Scanning Sense, though it has different limitations on the Not Blind advantage.

That would suggest the visual light only part, not negating the penalties, would be worth about the difference between Blindness and Blindness plus Not Blind (only in light), i.e. about that 10 points I think Color Blind is not covering.