Vision Rolls

[ScaredofScissors]

Hey all! I'm a long time fan of GURPS who finally is running a GURPS game <Transhuman Space even!>. A question about Vision rolls - how many people use the Range table modifiers with it? It seems like it makes spotting things even moderately far away rather difficult.

[NineDaysDead]

Originally Posted by ScaredofScissors

Hey all! I'm a long time fan of GURPS who finally is running a GURPS game <Transhuman Space even!>. A question about Vision rolls - how many people use the Range table modifiers with it? It seems like it makes spotting things even moderately far away rather difficult.

You remember you get +10 for looking at things in plain sight?

[whswhs]

Originally Posted by NineDaysDead

You remember you get +10 for looking at things in plain sight?

Yes, and if you do the math on eye charts, it looks as if once you've spotted something in plain sight, it ought to be +20 to make out fine details like differences between letters.

Bill Stoddard

[NineDaysDead]

Originally Posted by whswhs

Yes, and if you do the math on eye charts, it looks as if once you've spotted something in plain sight, it ought to be +20 to make out fine details like differences between letters.

Bill Stoddard

Letters on eye charts should probably get something like the +24 for Silhouetted*, and the +1 to +3 for contrast**.

*"In Space: +2 if the object is silhouetted against a larger celestial body, +24 if silhouetted against deep space. Note that this is cumulative with the plain sight modifier."
Spaceships 1, page 44.

**"Contrast provides +1 to +3 for moderate to high contrast between objects and background."
Mysteries Page 47.

[Anthony]

A standard Snellen eye chart has, for the 20/20 row, letters that are 5 minutes of arc, or about 1/700 of the range. That corresponds to a -17 to perception. It is, however, very high contrast. It should not get Silhouetted, however -- that only applies to a bright object against a black background, not a dark object against a bright background.

Silhouette against space is more extreme. Mars is fairly easily visible to the naked eye, and is a 7,000 km object at anywhere from 60-400 million km, depending on orbital position. Counting +2 for spherical, that's anywhere from a -21 to a -26, and corresponds to an apparent magnitude ranging from -3 to +1.4. Given how apparent magnitude works in general (+5 per x10 range), we can estimate spotting penalties as -24 - 1.2*AM, so for an object at the edge of visual detection (magnitude 6) we get a -31.

Note, however, that these limits are (a) essentially non-random for any given individual, and (b) completely uncorrelated with 'IQ'. The IQ/Perception part isn't the ability to see Mars -- it's the ability to know that that reddish dot is Mars.

[DouglasCole]

Originally Posted by NineDaysDead

You remember you get +10 for looking at things in plain sight?

Gratuitous link drop: In Plain Sight

[vicky_molokh]

Originally Posted by DouglasCole

Seriously, though, I have a hard time thinking of when you wouldn't just apply the +10 flat-out.

I've been wondering about when the +10 applies and when it doesn't, and eventually I got an answer from Kromm, in a roundabout sort of way:

Originally Posted by Kromm

There are none. To quote Active Sensors, p. B472: "They can sense objects out to their rated maximum range at no range penalty."

I would avoid most such complications. Our goal was to get away from the Third Edition model with range penalties and Scan ratings. That said, "in plain sight" appears to be nearly universal, and should apply to these senses. However, if the target is being even a little evasive, or if there's any cover – which is to say, in almost any combat situation – I wouldn't give this bonus. If a high-tech sensor shouldn't believably miss targets inside its range, that's what Acute Senses are for. Acute Radar and Acute Ladar are legitimate, and baseline Scanning Sense acuity assumes human perceptions, not technological ones.

No! By definition, camouflaged people or things aren't in plain sight.

The +10 never applies in hostile situations where one side would rather not be seen. It's specifically and exclusively for situations where the item of interest cannot avoid being seen . . . Thus, in most cases, using Camouflage or Stealth doesn't instantly give -10, because even someone without those skills would deny the +10 for "in plain sight" unless standing around like an idiot. I'd let any person avoid giving potential foes that +10 simply by asking, though they'd automatically be "up to no good" in the eyes of any cop or soldier (thus the "approach in the open with your hands above your head" order).

[Anthony]

My assumption is that someone who is trying to be sneaky and fails their roll gives a bonus, up to a maximum of +10.

[vicky_molokh]

Originally Posted by Anthony

My assumption is that someone who is trying to be sneaky and fails their roll gives a bonus, up to a maximum of +10.

That effect seems to be approximated naturally if handing Vision vs. Stealth as an honest-to-Kromm Quick Contest: since in a double failure, the winner is the one with a smaller absolute value of Margin of Failure, losing the roll effectively gives the enemy an advantage to see, but unlikely to be over an equivalent of 10 levels of bonuses except under the most unfavourable of circumstances.

[Classic Uncle Sam]

Originally Posted by ScaredofScissors

Hey all! I'm a long time fan of GURPS who finally is running a GURPS game <Transhuman Space even!>. A question about Vision rolls - how many people use the Range table modifiers with it? It seems like it makes spotting things even moderately far away rather difficult.

I have never used the range chart for something like this.

Often I will just fiat a yes or a no.

Sometimes a player will say they peak their head in to a room and want to know if they see Item X on a cluttered desk at the far side. I'll make a modifier depending on the size/distance at that point, but I have never gone by the range table.