[Mercer]

At my last session there was some discussion about whether or not the Chameleon Suit would work against Thermographic vision or whether that would be the Thermal Dampening armor mod.  We looked it up and as they say, that's when it got weird.

The Chameleon Suit give a -4 penalty to perception checks to spot the character.  We've always assumed that worked for all vision-based perception, thermo included.  But assume for the moment it doesn't, thermal dampening could easily be added to to a chameleon suit (or rather, would probably come standard as thermographic vision is pretty common-- roughly as common as low light).  But thermal dampening doesn't give penalties to the people looking for you, it gives you bonus dice versus those with thermographic vision.  So if you had a chameleon suit with thermal dampening 4, everyone looking for you visually would have a -4 to that check, and you'd have an extra 4 dice against those with thermographic vision.

It seems like getting bonus dice and giving a penalty gets weird, because if you're hiding from multiple people with different vision mods it can get fairly complicated.  For example:

*Full Darkness: Low light and normal observers are totally blind (-6), so it seems safe to assume they can't see anything.  Thero observers have a -3 from darkness and -4 for the chameleon suit which would be more than blind (although I could see capping it as -6, "Blind") and the thermal dampened suit would still get 4 more dice to roll against them.

*Partial Light: Normal and Thermo have a -2 from lighting, Low light has no penalty, so from the suit Therm and Normal end up with a -6, Low-Light with a -4, and the suit gets 4 bonus dice against the Therm. 

As you go down the list, against a thermal dampened chameleon suit, Therm comes in behind Normal vision on everything.  It has other advantages but it still seems weird to me.  It seems like either:

1) Chameleon suits don't work on thermal dampening, but you can add thermal dampening to them making it a wash (they don't get a -4, but you get a +4 against them).  Or,

2) Thermal dampening should be a penalty to thermo observers, and the chameleon suit is considered to have thermal dampening (4), making it a -4 to normal, low-light and thermo observers. 

Between the two the second seems the easiest to track because then you'd no longer have separate dice pools (and separate success tallies) depending on who was looking at you.

[Mirikon]

No, it works like you initially thought. Someone with a chameleon suit with thermal dampening 4 would get four extra dice against those with thermographic vision, and anyone trying to see them would take -4 to their Perception.

Honestly, you're overthinking things slightly. This is one of those situations where they kept things simple, in order to keep people from constantly rechecking mods. You have a chameleon suit? Everyone takes -4 to visual perception checks against you. You have thermal dampening X? Roll X dice extra on your Infiltration check. Apply other situational modifiers as normal.

[Halancar]

It's Thermal Damping, by the way.

And while the 2) might seem easier to track, by the rules it's actually 1), and it's even more logical if you consider real-world physics. It's at least theoretically possible to make a perfect chameleon suit, so you can take dice away from the Perception pool (which potentially reduces it to 0 dice); but heat has to go somewhere, so thermal damping can never be perfect (well, unless you are in a room at the exact same temperature as your body), so the idea is to make it less noticeable, which is an Infiltration test.

[Mirikon]

Not quite, Halancar. Unlike 1), you still get the -4 penalty to Perception checks to see you. It works on all visual perception tests. Again, a bit of simplification to keep things running smoothly. Thermographic is a type of visual perception, so you would still get the penalty. Likewise, Ultrasound would still suffer the penalty, since it is a type of visual perception. Astral Perception, however, would not suffer the penalty.

RAW, that's how it works. You can house rule differently in your game if you wish.

[Mercer]

I find it odd that the chameleon suit works against ultrasound, especially since ultrasound doesn't work against invisibility. 

The weird part of the chameleon suit/thermal damping is that you have different dice depending on who is looking at you, which is clunkier and more difficult to track than applying a penalty or bonus in one direction.  This isn't specific to this combo though, it's a problem that comes up a lot on perception tests and infiltration tests.  Say you have a runner team, some of whom are wearing chameleon suits and some regular armor with thermal damping trying to sneak up on sec guards who have  a mix of low-light and therm.  You end up with a situation where every guard and every runner have a different set of modifiers between them.  You either roll one perception check for each guard and track which dice are from which modifier (which is complicated on its own), or you roll separately for each guard trying to spot each runner.  Either way it's a headache.

[UmaroVI]

Chameleon suit is specifically against tests to see you, which Ultrasound is not because it isn't a form of vision.

[UmaroVI]

I do agree it is a huge headache. The right way to do it would be to have this sort of stuff increase PER thresholds by a static amount and you could probably hack that back on if you wanted.

[Crash_00]

Personally, I just disregard the surprise disclaimer on page 135 of SR4A and use that for my guards:

When an entire group of characters has a chance to notice something, the gamemaster can simplify matters by making a single Perception Test for the entire team, using the largest dice pool available + 1 per extra character (maximum +5).

Using this, you just roll for the highest DP and allow/disallow the Thermal Damping bonus based on whether the highest DP is using Thermographic or not. I always use individual rolls for the actual Reaction+Intuition part of the surprise check though.

Applying both as a penalty is simpler, but isn't quite as balanced when you get down to it (penalties are more powerful than bonuses, because they have a chance to auto-fail a target by reducing their dice to zero or less. This is really powerful against mooks that have a shared edge pool).

Chameleon suit is specifically against tests to see you, which Ultrasound is not because it isn't a form of vision.

It's a vision enhancement, and you do technically see the ultrasound map. In addition, you still suffer visibility modifiers when using Ultrasound. Personally, I don't feel that you should get hit with the full penalty, but I'd probably apply a -1 or -2 still.

[CitizenJoe]

Solution:  Chameleon suits don't work. 

The idea that you can use a camera to change a surface to show what is behind it is fine, except that surface has to be flat and the observer has to be at a specific point relative to the camera.  The observer similarly has to be viewing things with the same visual spectrum which the camera is using.  If you take a picture of a brick wall, then map it onto a sphere in front of that wall, the sphere can disappear if you're standing at just the right spot.  As you move away from that spot, the effects of perspective and angle of incidence change so that the pattern starts emphasizing the edges of the sphere.   When you look at the sphere from the side, it becomes very obvious since the camouflage pattern no longer matches the orientation of the camera.  Adding more cameras doesn't help, since you still only have the one surface to map the image. 

Now, if you can restrict the angle at which the observer can see the camouflage, then this becomes more feasible.

Note that active searches will tend to give away the subject as well.  A spotlight will not penetrate a chameleon suit, it will just show up as a white spot.

[Crash_00]

Out of all the questionable tech advances in SR I really don't think Chameleon Suits are the ones to gripe about. That said, the OP was asking a question on how they work in SR, not whether we can make them right now.

Give it sixty years and there will be advances in the field, even if it's not perfect. That said, chameleon suits are not perfect. They aren't invisibility. They are only 2/3rds as effective as invisibility. A midpoint between traditional camo and full blown you cannot see me. That leads me to believe that the chameleon suit doesn't map the background perfectly so much as mapping it as close as possible to match from all angles. Basically a dynamic camo that checks the background and displays a pattern to match as well as possible.

[CitizenJoe]

I can see them as programmable camo.  In that case, it acts as a camouflage suit appropriate to the environment, as opposed to locking in on one environment.  I can also see switching to active mode where you pick a observer location and it does the predator mask for that spot, but then you stand out to all other observers.    But they just aren't written that way. 

I think that the easier way is to where chromakey and then hack the cameras/eyes/AR displays to overwrite the background over that color.

[Crash_00]

I think you're horribly underestimating the ability for technology to advance over the course of the next 60 years. I mean we're talking the difference between the computer you're using now and the CSIRAC in advancements.

Popular Science had an article a year or two ago working on solving the perspective issue using a thick material with the pixels displaying at the base on the bottom side and a filter on the outer side that ran displacement algorithms to cause the picture to bend correctly when viewed from different angles.

They estimated within thirty years we could have relatively rigid semi-cloaking fabric (think poncho style). The actual physical science of it is way above my head (otherwise I would be considerably better off in life) but the main breakthrough was attributed to computer graphics advances.

[CitizenJoe]

All I'm saying here is that the Chameleon suits are borking physics so bad that if you want to use them due to Rule of Cool, then you should apply whatever else you want to them for the same reason and not look towards physics for any kind of help or sympathy.

So for the OP.  Chameleon suits by their description and by virtue of their Hollywood roots (Predator) do not provide thermal concealment (you can see the predator's hand through his thermal vision in one scene).  If you want to add thermal damping, follow whatever rules are written and don't think about how it works (because it doesn't).  It may involve the same restrictions as layering armor, it might not.  Just remember that when you open this can of rock worms that they too have the regeneration power.

[Murrdox]

All this is house-rule because I think RAW oversimplifies vision modifications, as other posters have already pointed out.

For an observer that is ONLY using Thermographic vision, such as a Thermographic camera, I would say that the Chameleon Suit does not work.  If the Suit has Thermal Damping, you get bonus Infiltration dice versus the camera.

For a living observer such as a Troll or Ork that has Thermographic vision but can also see normal visual spectrum objects, I would treat the Chameleon suit as a partial penalty of -2 instead of -4.  The Ork is going to have a little bit of a harder time detecting someone wearing a Chameleon Suit, since he can't see the visual spectrum, but he can still see the Thermographic bits.

The living observer modifier I could see going up and down depending on the situation.  If the Suit Wearer is in an empty warehouse with few heat sources, I'd probably only grant a -1.  The Thermographic signature of the wearer is going to stick out like a sore thumb.  However, if the Suit Wearer is outside, in warm weather, and there are multiple heat sources, such as other people, explosions, fire, animals, then I'd increase the penalty to -3.  Picking out the wearer's heat signature amongst all the heat sources will be difficult.

[Mirikon]

Murrdox's house rules are an example of why they simplified things. When actually running the game, it is much easier for everyone involved if the suit provides a static effect, instead of a changing one depending on the viewer and the environmental conditions, etc. When putting together these house rules, you should consider whether the additional complexity actually adds anything to the game, or whether it simply gets in the way of the fun. Does the 'realism' really add anything to your game? Or does it simply distract as you go looking up modifiers to fit the exact situation?