GURPS Powers: Enhanced Senses

[Flyndaran]

Originally Posted by Anthony

Most bees, ants, and the like have three receptors, like humans; most birds have four, a few birds and many butterflies have five. The tetrachromat version is a legit perk, but it's mostly for being a tetrachromat, not for being UV sensitive.

...

Okay, so that's where our disconnect came from. I assumed the mentioning of seeing UV being worth nothing referred to the addition of UV sight to Gurps basic 3 colors. Not UV replacing one of our three.

[vicky_molokh]

Originally Posted by Anthony

Normal Senses and Modifiers
Seems to be treating vision as 20p, hearing as 10p, smell as 2p, touch as 10p. Given that Blind is [-50], Deaf is [-20], No Sense of Smell is [-5], and Numb is [-20], those numbers are odd.

Probably as a matter of compromise, since it costs about [10] to get Infravision and apply some modifiers to it. And it costs [10] for a character with Infravision [0] to buy Normal Vision.

Originally Posted by Anthony

The Mark 1 Eyeball
The 20:20 letters on a Snellen eye chart are 0.35", not 0.07"; using a SM of -18 is equivalent to saying a human has SM -6 because his legs are only 6" wide.

Hmm. That might need recalibration, but the whole idea of getting more plusses for resolution of plain-sight details on a locked-on target seems on the right track. Making it official in some way.

[PseudoFenton]

The ability to detect UV is very good for spotting camouflaged predators in snow, which is why caribou have that sight advantage. I'm sure similar advantages can be applied to homogeneous landscapes, I'd think it'd be quite good at detecting urban-camo - although modern architecture insists on using metal and glass everywhere and I've no idea how much that'd mess things up.

[vicky_molokh]

Originally Posted by whswhs

In any case, I was able to rewrite Infravision because there are multiple bands of IR that can get through the atmosphere to different degrees, and that have different optical properties; the conventional GURPS treatment somewhat conflates the properties of very near IR with those of IR emitted by things like mammal bodies. UV has only one narrow band just above violet; higher frequencies don't get through the atmosphere—that's why they're called "vacuum ultraviolet." So I couldn't very well say "this is the version of the advantage that's limited to this narrower set of frequencies," because that narrower set of frequencies is what Ultravision is.

I suppose it was possible to rewrite the variant something like this:
Ultravision
Realistic Ultravision: [description of effects here]. [Cost of this variant here, if different]. Note: Ultravision from Basic Set can be used as a generalized UV sight advantage for a campaign with few scientific details.

[Flyndaran]

Originally Posted by PseudoFenton

The ability to detect UV is very good for spotting camouflaged predators in snow, which is why caribou have that sight advantage. I'm sure similar advantages can be applied to homogeneous landscapes, I'd think it'd be quite good at detecting urban-camo - although modern architecture insists on using metal and glass everywhere and I've no idea how much that'd mess things up.

Some birds detect UV so they can track rodents as urine shows up quite brightly.

[Refplace]

Originally Posted by Tiggurix

Inb4 someone declares they're making a mantis shrimp campaign now. :P

They already said that when GURPS Technical Grappling came out :)

[whswhs]

Originally Posted by Anthony

Normal Senses and Modifiers
Seems to be treating vision as 20p, hearing as 10p, smell as 2p, touch as 10p. Given that Blind is [-50], Deaf is [-20], No Sense of Smell is [-5], and Numb is [-20], those numbers are odd.

Yes, they are. But I examined the matter closely. In the first place, the precedent for this sort of thing is the rules for Extra Arms, about applying a modifier to the arms you naturally have. If, say, you take Short for one arm, the -50% modifier becomes a -5-point disadvantage, which implies that having an arm is worth 10 points (10 x -50% = -5). But One Arm is a -20-point disadvantage, so buying it off costs 20 points, not 10. Therefore the base value of the arm is not required to be the negative of the disadvantage of not having it. And the same can be true of the base value of sight, hearing, and so on.

In the second place, the rules for Scanning Sense make a 240° arc a +75% enhancement and a 360° arc a +125% enhancement; and they explicitly compare them to Peripheral Vision and 360° Vision. But those traits cost 15 points and 25 points. This implies an underlying value for Visible Light Vision of 20 points (20 x +125% = 25, for example). I thought it was desirable for all the other enhanced versions of human eyesight one might take to use the same implied value, for consistency.

I don't recall the details of how I got the point values for hearing, chemical senses, or touch, but if the use of a point value that's not simply the negative of the disadvantage for not having the sense is allowable for sight, the most important human sense, I don't see why it shouldn't be allowable for the others.

I wondered how long it would take before somebody brought this one up!

If we wanted to say that the base value had to be the negative of the disadvantage, then we'd have to change the Basic Set rules for modifying one or two arms; and, for example, we'd either have to make 360° Vision cost 62.5 points (Blindness is -50, and 50 x +125% = 62.5) or make Extended Arc, 360° a +50% enhancement (50 x +50% = 25). But either of those would change the RAW; my treatment does not.

[Anders]

Originally Posted by ErhnamDJ

Does it include rules for putting a maximum range on a sense, such as Dark Vision or Detect?

That's easy. No Roll Required allows you to automatically detect everything as long as Per-Vision modifier is 3 or greater.

[whswhs]

Originally Posted by Flyndaran

Okay, so that's where our disconnect came from. I assumed the mentioning of seeing UV being worth nothing referred to the addition of UV sight to Gurps basic 3 colors. Not UV replacing one of our three.

The Basic Set definition of the trait doesn't specify the number of receptor types. The fact that you get +2 for Ultravision does rather suggest that you might be getting a bonus for having more receptor types; I suppose you could parse it as +1 for tetrachromatism and +1 for extended spectrum.

[whswhs]

Originally Posted by Anthony

The Mark 1 Eyeball
The 20:20 letters on a Snellen eye chart are 0.35", not 0.07"; using a SM of -18 is equivalent to saying a human has SM -6 because his legs are only 6" wide.

That's true. But to read the charts, as opposed to seeing a bunch of blobs, you have to be able to make out the light and dark lines, which are necessarily narrower than the entire letter—the letter E, for example, has three dark and two light stripes. Dividing 0.35" by 5 gives 0.07" as the approximate width of each stripe.

And reading the line on the chart is what the optometrist asks for.