IR vision and Smoke...

[SirViss]

I just had one of my players ask me a question:

"You mean IR vision doesn't penetrate smoke?":nonp:

 

Smoke Grenades (as HERO equipment) is built as CE PER penalties to Sight Group. I don't know how good real smoke (from a smoke grenade) or tear gas is at stopping IR radiation from being perceived by the appropriate sensors. I was just wondering if anyone had an idea.

 

As of right now, to follow the dramatic feel that you often see in comics and action flicks, I am building "normal" smoke grenades with PER penalties to Normal Sight, and more advanced version to Sight Group, but I am just curious what people think about this.

[Guest Black Lotus]

Re: IR vision and Smoke...

 

I just had one of my players ask me a question:

"You mean IR vision doesn't penetrate smoke?":nonp:

 

Smoke Grenades (as HERO equipment) is built as CE PER penalties to Sight Group. I don't know how good real smoke (from a smoke grenade) or tear gas is at stopping IR radiation from being perceived by the appropriate sensors. I was just wondering if anyone had an idea.

 

As of right now, to follow the dramatic feel that you often see in comics and action flicks, I am building "normal" smoke grenades with PER penalties to Normal Sight, and more advanced version to Sight Group, but I am just curious what people think about this.

 

IR vision penetrates smoke.

[MitchellS]

Re: IR vision and Smoke...

 

That is, of course, just one type of smoke grenade. It could be built as thermal hot specks [which then block IR vision]. You can just as easily build one that only blocks normal sight.

[SirViss]

Re: IR vision and Smoke...

 

That is what I expected. I remember in on of the GURPS Tech Guides that they had Thermal Smoke to stop IR.

 

It's just that it gave me pause when I saw the build, and I had to think then how IR has been used in different media. In more than one instance, I remember the words:"Can't see them. Switching to IR... There they are!"

 

The main thing, in the end, was I was curious how smoke generally behave in "real" life.

 

Actually, how good is fog at stopping IR?

[Guest Black Lotus]

Re: IR vision and Smoke...

 

That is' date=' of course, just one type of smoke grenade. It could be built as thermal hot specks [which then block IR vision']. You can just as easily build one that only blocks normal sight.

 

"Thermal hot specks"? That a technical term?

[MitchellS]

Re: IR vision and Smoke...

 

"Thermal hot specks"? That a technical term?

It seems technical to a layman like me.

[MitchellS]

Re: IR vision and Smoke...

 

That is what I expected. I remember in on of the GURPS Tech Guides that they had Thermal Smoke to stop IR.

 

It's just that it gave me pause when I saw the build, and I had to think then how IR has been used in different media. In more than one instance, I remember the words:"Can't see them. Switching to IR... There they are!"

 

The main thing, in the end, was I was curious how smoke generally behave in "real" life.

 

Actually, how good is fog at stopping IR?

I have no idea how good it is. I could see it stopping IR due to the cool nature of fog [or at the very least distorting what you are seeing a great deal [possibly requiring additional PER modifiers]].

[Dr. Anomaly]

Re: IR vision and Smoke...

 

I just had one of my players ask me a question:

"You mean IR vision doesn't penetrate smoke?":nonp:

 

Smoke Grenades (as HERO equipment) is built as CE PER penalties to Sight Group. I don't know how good real smoke (from a smoke grenade) or tear gas is at stopping IR radiation from being perceived by the appropriate sensors. I was just wondering if anyone had an idea.

 

As of right now, to follow the dramatic feel that you often see in comics and action flicks, I am building "normal" smoke grenades with PER penalties to Normal Sight, and more advanced version to Sight Group, but I am just curious what people think about this.

Well, just remember: one of the main determining factors in EM "penetration" is the particulate size vs. the wavelength of the radiation. IR, being a longer wavelength than the visible spectrum, has better "penetrating" power than the visible spectrum because it takes a large particle size to block it, and the larger the particle size, the less likely you are to encounter them. Even in the visible spectrum, red light tends to be visible at a much longer distance than the same intensity of blue light. So for "normal" smoke, IR tends to penetrate where visible light doesn't. (Side note: that's one reason that a lot of deep-sky astronomy uses radio waves. Being even longer wavelength than IR, they penetrate clouds of gas and dust much better, and thus allow astronomers to "see" what is hidden by layers of gas and dust.)

 

If the smoke grenade is written up to block the sight sense group, I'd assume it's got "something for everyone" in its make-up; in other words, a component include to block each range of frequencies, including those outside of the normal visible spectrum.

 

(Further tending-toward-off-topic side note: Something that "Christmas tree rustlers" -- yes, Virginia, there really are [or were] such things -- would do would be to put a toggle switch in the electrical lines leading to their truck's tail lights / brake lights. The reason for this was they did their thefts as night, and the red lights from the truck's tail lights would be easily visible from a long way away, even through trees. By placing a switch in an inobvious location [such as under the back edge of the dashboard, behind the steering column], they could switch off their taillights before going on a "raid", but have them work normally for standard legal driving, vehicle inspections, etc.)

[SirViss]

Re: IR vision and Smoke...

 

Ah, a reply with a technical touch to it. I like those, thank you!

 

This seems to imply that fog probably isn't very good at blocking the IR part of the spectrum either. I'll have to remember that.

 

As to:

If the smoke grenade is written up to block the sight sense group, I'd assume it's got "something for everyone" in its make-up; in other words, a component include to block each range of frequencies, including those outside of the normal visible spectrum.

 

The only smoke grenade I remember seeing in HER is written with the Sight Group penalised. Why this is, I don't know. It just maybe that it is pretty cheap to do that way, and the fact that most HERO games involved superheroes, so IR sight/specks tend to be fairly common, so the average smoke grenade might effective vs that part of the spectrum because it is often encountered. Could be a simple oversight.

 

I just wanted to give the character that has the IR vision a little bonus because he actually bought IR vision. The thing is, that same player often gets hung-up on what would "really" happen. So, I am boning up on my knowledge of the subject before the next game, so I can tell the player(s) any changes I bring to the background. Like in this case, your average smoke grenade is going to be transparent to the IR spectrum.

[MitchellS]

Re: IR vision and Smoke...

 

The only smoke grenade I remember seeing in HER is written with the Sight Group penalised. Why this is' date=' I don't know. It just maybe that it is pretty cheap to do that way, and the fact that most HERO games involved superheroes, so IR sight/specks tend to be fairly common, so the average smoke grenade might effective vs that part of the spectrum because it is often encountered. Could be a simple oversight. [/quote']

I think it stems from the fact that Steve likes to give all his mercenary villains both IR and UV so he needed a grenade that can stop it all.

[prestidigitator]

Re: IR vision and Smoke...

 

Smoke is mostly transparent in the infrared spectrum, but opaque in the ultraviolet. Fog is generally not transparent to either, although there are a few wavelengths in the microwave and ultraviolet that penetrate through the atmosphere pretty well. Water in general is transparent only in the visible spectrum (here is a pretty good chart of absorbtion vs. wavelength; note that transparency at the low end starts in the radio band--quite a ways below infrared).

[zornwil]

Re: IR vision and Smoke...

 

These situations can definitely be difficult. The way I mostly handle them is to go ahead and pause, since it's usually situation-critical, and ask the player their understanding and if they're basing it on reality or genre or both (no wrong answer here but it helps to understand), plus consider the character's skills/experience/intelligence. Then go from there. Generally, I'll defer to the player so long as there's a reasonable rationale and it has no wider game or character ramifications (such as it essentially results in a free ability - e.g., if the guy said "my IR can go through hot air..." then I'd say, "well, okay, for the moment, but now you need to buy not IR but another ability to really do this, no matter how you think IR 'should' work".)

[Zed-F]

Re: IR vision and Smoke...

 

I would tend to think that IR would not work well in fog due to the water absorbing the radiated heat energy. Water particles can be fairly large by EM radiation standards. Microwaves are even longer than EM waves, and water generally stops them nicely.

[SirViss]

Re: IR vision and Smoke...

 

prestidigitator & Zed-F: Good to know (Note to Zed-F: check the link that prestidigitator posted. Definetly supports what you just said )

 

zornwil: Yes, that kind of situation can be difficult. Unfortunately, this game suffers enough tangential discussions without my encouraging it. Heck, I' m probably the worst of the lot when it come to that.

 

I am usually flexible enough to impliment a small adjustment for the particular situation to make it fun for the players, but in this case I was TOO prepared for the session. I had gone over everything that was going to be used by the bad guys, and had noted how the smoke grenades where built. So when the question came up as to IR and the CE, I said "no".

 

Another contributing factor is, unless I am given good reason, if i use something from the book I stick to it (K.I.S.S. principle). The player has his say, if he wishes, I ponder it for a few moments, then I make a decision. If the player doesn't agree with the decision, he can argue his position after the game. In this case, I would probably have caved fairly easily, but the player (one of my best) didn't present his thoughts on the matter, so the game resumed with no changes. And we still had fun!

 

At least, next time some similar situation will come up, I will be ready. (Riiiiight... )

[Sean Waters]

Re: IR vision and Smoke...

 

Hmmm. Hot air will effectively block IR vision, I'm afraid, so if the smoke is created from, say, a fire, and is hot then it will block or at least interefere with IR vision - you can't see heat through heat. In a room at body temperature, everything is giving off radiation in the wavelength of IR and humans are invisible, even if you can see them fine with normal vision. Mind you IR coiers quite a range of wavelengths....

 

Smoke doesn't block IR anywhere near as much as it locks normal vision, and firefighters use IR equipment, so even my 'hot air' comments are only partially true. Mind you I daresay you could create a smoke grenade that had particles the right size to interfere with IR.

 

The answer then is this: if it is built to block the whole sight group, it blocks IR, if it is built to block normal vision it doesn't.

 

This is worth reading...and it specifically mentions the effect of smoke.... http://en.wikipedia.org/wiki/Infrared

[Sean Waters]

Re: IR vision and Smoke...

 

To widen things a bit, it is not just smoke that IR can see through - it can see through foliage, thin walls and all kinds of stuff that can block normal vision. We have police helicopters in Dorset that are absolute mustard at this sort of thing. Moreover, if you sit in a chair then get up the chair will still register your (fading) presence for a while in some bands of the IR spectrum, so it can usefully be used for tracking in some situations (especially if barefoot and/or against a thermally contrasting matrix), or at least telling if someone was in the room within the last few minutes. If sensitive enough you can also tell which buttons were pushed on a keypad, and, by intensity, in which order, although, if you were to allow that in-game I'd requie some really impressive PER rolls.

[prestidigitator]

Re: IR vision and Smoke...

 

Hmmm. Hot air will effectively block IR vision, I'm afraid, so if the smoke is created from, say, a fire, and is hot then it will block or at least interefere with IR vision - you can't see heat through heat. In a room at body temperature, everything is giving off radiation in the wavelength of IR and humans are invisible, even if you can see them fine with normal vision. Mind you IR coiers quite a range of wavelengths....

 

Smoke doesn't block IR anywhere near as much as it locks normal vision, and firefighters use IR equipment, so even my 'hot air' comments are only partially true. Mind you I daresay you could create a smoke grenade that had particles the right size to interfere with IR.

Those things are like saying you can't see something that is close to a lightbulb, or someone wearing white in a white room with a lot of ambient light. To be sure those things can make it more difficult, but the (Discriminatory) human eye is a pretty accurate device.

 

The answer then is this: if it is built to block the whole sight group, it blocks IR, if it is built to block normal vision it doesn't.

Yeah. If using real equipment in a heroic campaign, I would probably be more inclined to redefine the power the equipment is based on (when specified) if it is supposed to model something IRL that the current build does not reflect (so I might say, "Oops. That smoke grenade should have a -1/4 on the Darkness/Change Environment that excludes the IR Vision sense"). If it is a Power that has been paid for by a character, I'd be more inclined to add to the SFX a little ("This advanced smoke grenade emits particles that are specifically designed to scatter IR as well as physical light"), unless the character wanted to change the power to be a little more limiting in order to represent the desired RL effect.

 

This is worth reading...and it specifically mentions the effect of smoke.... http://en.wikipedia.org/wiki/Infrared

Cool. I didn't stumble into that one. Sometimes I forget about Wikipedia; it is such a great resource!

[prestidigitator]

Re: IR vision and Smoke...

 

To widen things a bit' date=' it is not just smoke that IR can see through - it can see through foliage, thin walls and all kinds of stuff that can block normal vision. We have police helicopters in Dorset that are absolute mustard at this sort of thing. Moreover, if you sit in a chair then get up the chair will still register your (fading) presence for a while in some bands of the IR spectrum, so it can usefully be used for tracking in some situations (especially if barefoot and/or against a thermally contrasting matrix), or at least telling if someone was in the room within the last few minutes. If sensitive enough you can also tell which buttons were pushed on a keypad, and, by intensity, in which order, although, if you were to allow that in-game I'd requie some really impressive PER rolls.[/quote']

Thin foliage (grass, light density shrubbery) and really thin walls, and all these effects require a pretty darn sensitive sensor! But yeah, such effects could probably be a great SFX basis for Discriminatory, Tracking, etc.

[zornwil]

Re: IR vision and Smoke...

 

To widen things a bit' date=' it is not just smoke that IR can see through - it can see through foliage, thin walls and all kinds of stuff that can block normal vision. We have police helicopters in Dorset that are absolute mustard at this sort of thing. Moreover, if you sit in a chair then get up the chair will still register your (fading) presence for a while in some bands of the IR spectrum, so it can usefully be used for tracking in some situations (especially if barefoot and/or against a thermally contrasting matrix), or at least telling if someone was in the room within the last few minutes. If sensitive enough you can also tell which buttons were pushed on a keypad, and, by intensity, in which order, although, if you were to allow that in-game I'd requie some really impressive PER rolls.[/quote']

Yeah, that reminds me of a player in the prior campaign who thought he should see through walls with IR due to realism...almost forgot.

[Sean Waters]

Re: IR vision and Smoke...

 

Senses are often difficult to administer. If I lean against a wall on a cold night, when I leave it will retain my heat print for a while. If I lean there long enough then you will be able to see my heat print from the other side.

 

Being able to see a heat print doesn't identify a person though. You may be able to guess species from the general outline - or you may not - but the discriminatory potential is limited where there is this sort of 'indirect' observation of IR: you know SOMEONE is leaning against the wall, but is it a guard or a hostage?

 

RoboCop has a lot to answer for

[SirViss]

Re: IR vision and Smoke...

 

Well, Senses ARE difficult to adjudicate, but I try to keep it "game Logical". at least.

 

Sean: Most of what you mention, I had some passing knowledge of, at least (gotta love Discovery, and other such channels ). The main things I wasn't clear on was smoke and fog.

 

I would like an example of a "thin wall". Ply wood?

[Sean Waters]

Re: IR vision and Smoke...

 

Well, Senses ARE difficult to adjudicate, but I try to keep it "game Logical". at least.

 

Sean: Most of what you mention, I had some passing knowledge of, at least (gotta love Discovery, and other such channels ). The main things I wasn't clear on was smoke and fog.

 

I would like an example of a "thin wall". Ply wood?

 

Depends. Basically anything that either doesn't stop IR or that you stand near enough to to heat up with your body. Often it is about thermal contrast, so IR often works rather better at night when it is colder and there is less ambient IR anyway, but it still works during the day and can sometimes be more effective than normal vision even during daylght.

 

http://www.dorsetpolice.org/operations/airsupport/equipment.shtml

 

As for seeing through walls, well you can certainly see through, say a tent, and basically anything thin enough to conduct heat through it. Thin wooden walls, so long as the person inside was not moving around too much. You are not going to get anything other than very basic information though (a 'hot spot'). Mind you if someone was inside a wooden hut/portacabin for any length of time it would start to heat up, so it may be obvious there is someone there even if you can not say exactly where...

 

Try this page too:

 

http://www.auroratactical.com/thermal-imaging.htm

 

IR vision covers both night vision and thermo-imaging. Of course you can go quite mad trying to recreate reality in game terms. My advice would be to simply agree what a particular sense can and can't do and not let players come up with...'but IR vision CAN do that...!'

[prestidigitator]

Re: IR vision and Smoke...

 

IR vision covers both night vision and thermo-imaging. Of course you can go quite mad trying to recreate reality in game terms. My advice would be to simply agree what a particular sense can and can't do and not let players come up with...'but IR vision CAN do that...!'

Some night vision. A lot of night vision applications simply use light amplification in the visual range (some do both). I just learned something: the 2000 Cadillac DeVille had a thermal imaging system for nighttime driving! It is the first (and so far only) such system to go into production. They discontinued it, though.