Light sources and vision question

[bocephus]

I haven't been able to find any reference or table to help me figure out distance modifiers for vision. Specifically how much 'no penalty' distance do you get with different light sources.

First all my questions are phrased based on the below being basically correct:

Outside, normal light, no specific mitigating circumstances - shooting a 'laser' (IE weapon that does not dissipate or have ballistic modifiers) with normal vision and no mechanical or other advantage (IE everyman). When do you start getting "vision/long range negative modifiers" stuff based on the person and not the weapon? The only table I have at the moment is in the long distance modifiers table for information spells (that's not it). There is a plethora of data that refers to ballistic weapons using the weapons stats. How far out can a caster ID a target and start aiming? The "weapon" is just sight and innate attack, in theory if the caster can see the target clearly he's just waiting for it to get where it needs to be in range of the spell. If that's not correct then its possible my questions will not make sense.

As to my question is how does the light source effect this? I will give a couple of reasons so it will hopefully make sense why and what I'm talking about.

1) Fireball Caster on an open field shooting a stationary man size target at max range (50) would be half damage but no penalty for anything vision related.

2) Underground cavern - no natural light

A) How far can the normal human see with a candle / torch / 'sunlight bright' flashlight? I assume the flashlight is just normal vision.

B) The "normal human" is blind, a char with Dark vision can see more or less normally to 60ft. Does a torch interfere with Dark vision? Can the Dark vision function simultaneously with a lesser light source without loosing the 60ft range of vision?

C) A caster has cast continual light on a, what ever, at 'candle light', how far can he cast a missile or the archer shoot without incurring a modifier?

D) Using a simple contraption that is more or less a 'no lens' bullseye lantern (basic idea was to keep the light projecting forward not in your face like a torch) and a 'sunlight bright' light source in what ways would you modify the vision for distance, to the sides, camouflage, etc?

Would the caster/archer be essentially at no penalty to see normally and target something as normal (assuming the light is shining on it).

Would you penalize natural subterranean creatures whose camouflage doesn't take into account natural light?

Lastly how would you rule an archer/caster that is shooting at a target in torchlight but the torch is 30 hexs away? IE there is a guard standing with his back to a wall with a torch behind him. The archer/caster is standing in a treeline in the dark with enough cover that he is not staring at the torch, would you impose any sort of vision penalty at all to hit?

[whswhs]

Of course there are modifiers for distance any time you go past 2 yards. But if something is in plain sight, like a man in high-visibility clothes standing up, or a black letter on a white page, you get +10 to spot it and +20 to examine it closely once you've spotted it (the latter is in GURPS Powers: Enhanced Senses, under The Mark One Eyeball, p. 14).

Light levels have separate effects. The most detailed rules for effects of illumination at range, based on geometry of the light source (sphere, hemisphere, or focused beam) can be found in GURPS High-Tech: Electricity and Electronics, under Light Levels (p. 20).

(I must confess that I am recommending my own books, as I wrote both of those, which is why I remember them!)

To look at one of your questions, torchlight gives -1 to vision within a basic 1-yard radius. This becomes -2 at 2 yards, -3 at 3-5, -4 out to 10 yards, -5 out to 20 yards, -6 out to 50 yards, and so on, until you reach the ambient illumination level (a light source will never reduce the light level!). If you're in total darkness, and you have any light source, the worst light level penalty will never be worse than -9.

However, in addition to whatever light level penalties apply, you must apply range penalties for apparent size of the target: -1 at 3 yards, -2 at 5, -3 at 7, -4 at 10, and so on.

So in the case of your archer, target, and torch, the torch appears to be right next to the target, so he's dimly lit for a -1 penalty. But the archer is 30 yards from the target, which is a -7 penalty. That's a total of -8.

I would rule that the target is "in plain sight," for +10 to spot, a net +2. Having the torch behind the target isn't going to let you see many details—all the well lit ones are on the wrong side; as a simple approximation I'd say you can make out the silhouette at a net +12. I don't think the surface facing toward you is "in plain sight," so it's at -8. Actually shooting at the target has -1 for light level and -7 for range is a base -8, to be adjusted if you take the time to aim, of course.

[Refplace]

I'll second the authors recommendation. IMO the best lighting rules are in GURPS High Tech: Electricity and Electronics which discusses shaping the light such as a flashlight or a open light.
Enhanced Senses is also good and there is some duplication (it came first) but it covers a lot of other senses useful for most settings.

One thing about GURPS books is they are written so as to require as few books as possible to play a game.
You need the Basic Set, but anything after that is more refinement and additional options for specific things. Rules and material are duplicated where appropriate so you dont have to buy every book just to make sure you have every little obscure option.

[bocephus]

whswhs:
Im going to separate the responses a little because I feel like either I didnt understand the answer or you might have misunderstood my question. Also I dont have those books, sorry not my genre. I dont know if you feel like I have the 'daylight' rules correct or are correcting that...


Of course there are modifiers for distance any time you go past 2 yards. But if something is in plain sight, like a man in high-visibility clothes standing up, or a black letter on a white page, you get +10 to spot it and +20 to examine it closely once you've spotted it (the latter is in GURPS Powers: Enhanced Senses, under The Mark One Eyeball, p. 14).

Of course... what modifier for going past 2 yards, do you just mean in the dark? I truly dont understand what your alluding to, unless your are just ignoring the bits I got correct and Im getting twisted up about nothing in my zest to understand this :) hehheh




To look at one of your questions, torchlight gives -1 to vision within a basic 1-yard radius. This becomes -2 at 2 yards, -3 at 3-5, -4 out to 10 yards, -5 out to 20 yards, -6 out to 50 yards, and so on, until you reach the ambient illumination level (a light source will never reduce the light level!). If you're in total darkness, and you have any light source, the worst light level penalty will never be worse than -9.

That is a perfect answer, and exactly what I was looking for in terms of how does variable light affect skills. I sort of think its scales wonky but I can use that, I dont think Im going to let them get that far out at -5 and -6 etc



I would rule that the target is "in plain sight," for +10 to spot, a net +2. Having the torch behind the target isn't going to let you see many details—all the well lit ones are on the wrong side; as a simple approximation I'd say you can make out the silhouette at a net +12. I don't think the surface facing toward you is "in plain sight," so it's at -8. Actually shooting at the target has -1 for light level and -7 for range is a base -8, to be adjusted if you take the time to aim, of course.

If I get this correctly your assessing a penalty to the archer for the darkness between him and the target? If your shooting at a silhouette and want a "called shot" Im on sort of board as you stated the wrong side is lit, but I just want center mass and I'll take what I get. I could see the minus 1-2 because of the lower light level at the target, but I dont track the -7 to range, I can "clearly" see the lit target.

Im still searching for a Daylight vision scale, as in Identifying a man size target at 25/50/100/150/200 .... or am I getting bogged in details?

[Refplace]

Originally Posted by bocephus

Of course... what modifier for going past 2 yards, do you just mean in the dark? I truly dont understand what your alluding to, unless your are just ignoring the bits I got correct and Im getting twisted up about nothing in my zest to understand this :) hehheh


Im still searching for a Daylight vision scale, as in Identifying a man size target at 25/50/100/150/200 .... or am I getting bogged in details?

I'll take a stab at your question here.
When looking at or for something you take a penalty for distance, see p. B358, specifically the Vision section in this case.
Roll against Per to see something with modifiers for Acute Senses, range, etc.
Darkness also gives a penalty which light can counter but this is where it gets tricky.
A source of light makes it easier to see but the light gets weaker the farther away from its source, different light sources will lose their effectiveness at different distances a torch is not as visible as a bonfire for example.
WHSH (Bill or William Stoddard) gave that drop off for a torch.
The torch will make it easier to clearly see a target but that is less helpful farther away so its bonus drops off over distance but will never be worse than the ambient light/darkness.
However there is a case for the high contrast so you can see a torch in darkness farther than it provides useful light.

[whswhs]

Originally Posted by bocephus

Of course... what modifier for going past 2 yards, do you just mean in the dark?

No, not at all. Refplace has pointed you at the correct place. There are range modifiers to both vision and aiming ranged weapons (spells, ranged powers, etc.): 0 for 2 yards or less, -1 for 3 yards, -2 for 5 yards, -3 for 7 yards, -4 for 10 yards, -5 for 15 yards, -6 for 20 yards, and each x10 range is another -6 (so for example, for 100 yards, 100 is 10x10, 10 is -4, and another -6 gets you to -10). This are IN ADDITION TO modifiers for low light; they apply even at high noon.

If I get this correctly your assessing a penalty to the archer for the darkness between him and the target? If your shooting at a silhouette and want a "called shot" Im on sort of board as you stated the wrong side is lit, but I just want center mass and I'll take what I get. I could see the minus 1-2 because of the lower light level at the target, but I dont track the -7 to range, I can "clearly" see the lit target.

Actually, no. I was talking purely about penalties to SEE the target in the first place. Under the conditions you describe, I figured three penalties:

The target is lit by torchlight, and is close enough to get the full benefit of the torch, which is a low light penalty of -1.

The target is 30 yards away, and that's 10x 3 yards, and the penalty for 3 yards is -1, so the penalty for 30 yards is -1-6 or -7;

If you are just talking about noticing that the target is there, I would say that the dark figure of a man standing between you and a circle of torchlight counts as "in plain sight," which is actually a bonus of +10; putting that with the two penalties is a net +2.

If you are talking about seeing the outline of the man's form, so you can tell details like tall or short, fat or skinny, naked or armored, or carrying a large weapons, that doubles the bonus to +20 for a net +12, but only for details you can make out from the silhouette.

Trying to shoot the target, you don't get either of these bonuses. Your modifiers are -1 for low light and -7 for range, for a net -8. But in that case you can take a second or two to get the aiming bonus for your weapon and possibly other bonuses that can compensate.

Im still searching for a Daylight vision scale, as in Identifying a man size target at 25/50/100/150/200 .... or am I getting bogged in details?

That's the one Refplace was pointing out.

[bocephus]

I found that chart, and I have to say thats just wrong, from any point of "realism". At least in so much as applying it to distance of a stationary man size target using a trained range weapon. I though that chart was only to determine movement modifiers (which I think it works wonderful well at).

If I understand the chart, basically its saying that I should have a -10 to shoot a target with a weapon that has an Effective range (the edge of the full damage range) because its 100yds away?

By the same token this same weapon is at a 0 modifier if I use it at 2yds? This is rhetorical but necessary for to follow the reasoning.

Im an archer, in real life (amateur archer and bow hunter) as well as for the sake of this exercise. I understand my skill but I have also introduced and helped train a fair number of beginners, I believe this qualifies me to speak about skill level10 Dex-1 (which I think is realistic) and has a 50% chance of hitting a target consistently.

Consider it this way. You take up archery as a young laddie and finally gain proficiency enough to say I am skill level "1" with a slightly above average dexterity of 11 I now claim as skill of 10 (or about 50% probability of success). At no point EVER in the history of ever have you fired an arrow at a target 2yds away. I dont mean that as alliteration, I mean to say if you ever did it you would be asked to leave any organized training cause well.... really. You can spit that distance theres no point to it.

I have never, not once ever trained to shoot a target at 2yds. Why would anyone intending to use this skill in combat / hunting do something so idiotic, I theorize a "charging animal drill" (but if your using a bow in that situation you have bigger problems) and such a thing doesn't exist for a dismounted archer. If you want to train with a bow you would do it at the ranges you would expect to use it, including training to use it for multiple ranges. All of this is represented in your skill at bow.

Why would my baseline for using a bow that has a max effective range of 150yds, and I train to shoot it between 25 and 75 yards, give me a skill of 10 (meaning I can hit a target the size of a plate 50% of the time between 25 and 75 yards) suddenly mean I can only hit a target 50% of the time at TWO yards? HUH? Now 100-150yds I see a modifier because it starts getting hard to see your target, but keep in mind we are training with a plate not a person size/shape target.

I whipped this up last night as it began to dawn on me that this was infact exactly what the "books say" so I wrote house rules that take the chart into account (I like the chart) but remove that crazy penalty for distance to a "Trained Archer".

Range chart (b550) applies to muscle powered Range weapons using 1/3 max effective range (the edge of the full damage) as the 0 point for a stationary target. Range modifiers after that point increment the same.
Example: An archer with Dex 11 and Str 10 and 1 point in Bow. Skill 10 in Bow (hits about 50% of the time).
Regular bow with an operational range of 150/200 (that's a HUGE stretch to realism,but I like 95% of GURPS the way it is so I leave that alone). 1/3 of that effective range is 50.
Standard arrow nothing special no flight mod.
At 50yds (50 on the chart) is your penalty is 0
Your range penalty scales at half so 50 is 0, 55 is -1, 60 is -2, 70 is -3, 100 -4, 150yds your at -5
Likewise you get a bonus for each double interval closer to you 20yds +1, 10yds +2, 5yds +3
Range Chart Movement modifiers apply as written.
Range chart size modifiers apply as written.

I will have to playtest this to see if I need to slide it one direction or another. I know from practice that hitting a 100m target with a bow is NOT a -8 difficulty, it starts getting small and hard to see really fast, but again its a plate not a torso with a head on it ... size matters. I like the sliding scale that increments like the bonus for short distance. Using b550 chart scale the distance at half the penalty, at 150yds your at -5, which feels ok... I would say you have a 50% of a 50% (around 5% chance) to hit a 150yd target at the far edge of your weapons capability if your only hitting at 50yds 50% of the time.

ST bonus would only apply if your weapon is built for it, extending your effective base distance without changing your chance to hit. Now we are moving into familiar vs unfamiliar weapons and and and... but I feel more comfortable with this than telling an archer that he has a -8 to hit a target bigger than he trained on, at a distance that he's trained at.... sorry but unless you just hate the idea of missile weapons existing thats just unfair in the extreme.

[whswhs]

Of course there is nothing to stop you from using any set of house rules you care to make up. But I wasn't attempting to comment on the validity of the existing rules; I was only attempting to make it clear how they work.

[bocephus]

No judgement on your interpretation of the rules, I just wasnt doing that and we need to have a common understanding so that we can discuss anything.

Also I wasnt aware that I was imposing rules "incorrectly" and no one ever called me on it so I was just sort of doing it, but never really understood why the system didnt seem to work for me (as in didnt address the mechanics of distance) was just because it doesnt seem to address archery really, its more focused on firearms (which I do as well hehheh).

I believe I have resolved the light situation based on what you gave me. I know have an actual mechanic for archery that makes sense for me.

This thread really was a good one for me and my players, and Im excited to talk to them about it. I suspect this is why my Medieval Fantasy group has always stayed away from range weapons, perhaps they understood someothing I didnt and just wrote it off.

[evileeyore]

Originally Posted by bocephus

If I understand the chart, basically its saying that I should have a -10 to shoot a target with a weapon that has an Effective range (the edge of the full damage range) because its 100yds away?

You're ignoring Acc, Aiming, and the bonus for being on a calm range not in combat, possibly the size of the target, and knowing the range.

The last two aren't bonuses laid out* in Basic because Basic is focused on stressful action and combat, not leisurely plinking away at practice.



* I mean they are, to a point, in that GMs are given the guideline of applying bonuses for easier actions.