[vicky_molokh]

Sense Rolls, Stealth and Camouflage

Originally Posted by Kromm

This is a long response, so I've had to split it in two to avoid the character limit for a PM. Note that this took a lot of time to write, so I simply can't justify follow-up comments. I hope these answers will suffice!

I'd go with the 1/4 yard implied by High-Tech, p. 158 if the person is truly stalking. The Stealth skill gives -5 when Moving faster than Move 1, however, which is functionally equivalent to +5 to Hearing, making the distance 8 yards at Move 2+. That's too coarse-grained, so I'd prefer to say that base distance equals the stalker's Move. Thus, any combat movement (Move 1+) is audible at full Hearing at one yard; sneaking to within stabbing distance is a simple Quick Contest of Stealth vs. Hearing; and the High-Tech case assumes someone moving at Move 0.25.

That -2 is more for "surrounding noises" (p. B358) than for distance. It's also a simplification; note that neither the distance nor speed of an unseen attacker affects this Hearing roll. I wouldn't attempt to rationalize this. If you must, then use standard distance = Move and apply an extra -2 in a fight, so that someone running at Move 5 is heard at -2 at 5 yards, -1 at 2 yards, no modifier at 1 yard. Just stepping a yard means he's heard at -2 at 1 yard (which is the most usual case in combat).

Vision rolls get +10 for "in plain sight." Those use a progression where every -6 is ×10 – i.e., Vision gets an effective x10^(10/6), or about ×50, range in unchallenging situations. The equivalent for Hearing would be +5 or +6. I'd pick +5, as it's easy to remember and gives ordinary conversationalists a Hearing roll of 15 at 1 yard or 14 at 2 yards, which allows for the occasional "Sorry, what was that?" moment that happens in real life.

That's more a research question than a rules question. As a rough guide, call it -4. That way, Discriminatory Smell's +4 cancels it out. Ordinary people would be rolling against 6, which seems believable given our atrophied olfaction. If the objective is to spot an impersonator, I might give a bonus of +1 to +4 if the person rolling is intimately familiar with the subject – say, +1 for a friend, +2 for a best friend, or +3 for a lover, and another +1 if you've lived with the subject.

That has never been established. I'd apply standard range modifiers, a separate bonus or penalty for windspeed, bonuses for large sources (say, equal to SM) and strong smells, and up to +5 (for "extra time") for persistent sources. Thus, a huge factory (SM +10) that's a mile away (-18), spewing a foul smell (+4) constantly for days (+5) would be detectable at Smell+1, or possibly Smell+2 or Smell+3 with the right wind. A human (SM 0) a yard or two away (0) wearing strong perfume (+1) in a still room would be detectable at Smell+1 when she walked in, or Smell+2 if she had a lot of perfume on – and you'd add up to +5 after she'd been in the room for a few hours. So don't try Stealth if you like perfume!

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).

That -1 is for a blurry outline vs. ranged attacks. Anything more serious would require advanced tech or superhuman abilities. Obviously, smoke could do it with fairly low tech, but that is unsubtle concealment, not camouflage per se.

Canonically, Sense rolls are free actions and not subject to time modifiers. If you fail, you can't retry until something changes to improve your Sense roll: the range decreases, the target turns on bright lights or sounds a horn, whatever. I can't think of a fair modifier that wouldn't be a free bonus for everyone outside of combat, though I might be nice and grant someone who's exclusively scanning and doing nothing else the same +2 that Aim would give after three seconds.

Originally Posted by Kromm

Stealth prevents being seen and being heard. Its main uses are hiding from sight behind concealment or in shadow, and treading lightly. However, very little in the way of gear gives a bonus in that situation; mostly, the more gear you have, the harder it is to hide, thanks to encumbrance. Dan was describing equipment bonuses, not skill effects.

Camouflage only prevents being seen. Its main use is hiding from sight by breaking up outlines and disguising oneself as part of the environment. A lot of gear gives a bonus in that situation. Again, Dan was describing equipment bonuses, not skill effects.