This is something that is almost insanely difficult to enumerate.

First off, people only leave hot little footprints if the temperature of the walking surface is substantially less than the 98.6F of the human body, and depending on the external temperature, the time it takes for the heat to dissipate may be all too quick for any tracking, unless you're just a few steps behind the target.

Honestly, I wouldn't allow for this kind of tracking unless the tracker was VERY close behind the target in terms of time, such as arriving a few seconds to a minute after the target has passed at the very most. Metal flooring would hold the heat of footprints best, a thin sheen of water would dissipate it almost immediately, and if the target was running, their feet may not be in contact with the ground long enough to transfer enough heat to last more than a few seconds.

I would love to be proven otherwise, but footprint-heat tracking is pretty much myth in my eyes. But, in the SR world we have magic dwarf eyes and super-high-tech goggles, so maybe it is possible.

The term "footprint" could be a generic term for any difference in heat left behind. But anything that is not of the same ambient temperature of the object is placed on will change the temperature when contact is made, and will show up as a different color until the heat balances out to the mean temperature again. It's actually pretty cool. A real life way to thwart thermal imaging is by placing glass between the imaging system and whatever it is you are trying to see. Glass just shows up as a "black" spot. I never really knew that till I got to mess around with an Thermal camera system at our local Science museum. But since they never wrote that into the game, it's "movie" thermal.

You're also forgetting one more thing...shoes.

Unless you're running after somebody that's barefoot, they're unlikely to change the surface's temperature at all, let alone enough that you could see it with thermal imaging.

So my answers to your questions are:

How do you guys play this? I laugh in the face of such munchkining.

Do you allow runners to see the footsteps of people? Hell no. (not the "thermal residue" of a footprint anyway)

If so, how long does the heat imprint last? N/A

That out of the way, I do believe:

I'm glad to see you guys agreed with my assessment. I quite literally laughed when a player tried to tell me you could track footsteps with thermographic vision. Then he showed me the text and I wasn't so sure.
I told him, that I wasn't going to allow it until I looked into the matter some. It's a player new to Shadowrun in general and that is the only reason I didn't just flat out say no.

Well, with real world infrared cameras it is possible to see footprints. But only after the person leaving the prints stood in one place for some time on his bare feet. The effect of glass on the image depends on the heat isolating capabilities of the actual material you are trying to look through. Window panes will be opaque.

So, what IS a heat footprint, exactly?

Read the First Post in the Tricks For the Criminals in training thread.

If they can do it now, they can probably do it then, but in both situations, its probably pretty easy to fool.

Well, it's not an unbiased report or anything, but ThermovisionTM claims that you can see footprints on carpet with thermographic vision. And that's with a crappy early 21st century hand-held unit. I can only imagine that actual Dwarves and Trolls would be a crap tonne better.

-Frank

Yah, I stand by my earlier post, but shoes are usually not the same temperature as a floor, so there would be a transfer in heat that would be visible to a sensitive enough system. But unless you have a physics degree and know the heat transferance capabilities of any material that someone may walk on you would just have to make a GM call. No one has tried to do it my game yet, but given the advanced sci fi technology of Shadowrun I don't see it out of the realm of possibility to track someone who has just walked on a surface a few minutes earlier. But generally, I can't think of anything that would still retain that small of a heat transference for anything longer than a couple of minutes, definitely not hours later.

Gawd, all this stuff is makes me shudder as I start having flashbacks to what I've learned in my heat transfer class years ago...

A person does not heat up a section of floor much by heat transfer when they walk on it with insulated shoes. However, a 75 kilogram man who runs across a room has actually put a considerable amount of force against each section of floor.

Force = Pressure = Heat. You remember your gas laws, right? By putting enough force on the ground to launch yourself into the air via equal and opposite reaction, you've definitionally put a considerabl amount of energy into the floor. Some escapes as sound, the rest is heat.

-Frank

My personal house rule is Threshold 2 + ( 1 per minute).
Of course, that's just me

Here's a random question only slightly related to this thread - does thermographic vision see through walls? I'm not terribly sure, as a member of our group seems to think yes, and I was inclined to believe him until I heard here that glass will stop thermo (and, according to certain pictures, so do heavy clothes?). Anyone have any information regarding this? Thanks.

Stealing from a certain drow in FR (D&D), sometimes when I am playing, we all get thermographic goggles, and our stealth specialist will leave heat hand print patterns telling us which way to go.

Rubber soled shoes pretty much kill the idea of heat foot prints though. If someone touches a wall long enough, that might give you an idea of the size of at least one person that was there.

A note on thermographic vision:

IR does not see "heat". It sees light. Low intensity light, but light. Things emit light all the time, and the more energetic they are, the higher the frequency of the light they admit. You can see this in action by taking a metal object and holding it in a fire (use tongs). As the metal heats up, it becomes more energetic and releases higher and higher frequency light.

As the metal gets hotter, it will eventually start releasing light so energetic that you can actually see it - and the object will glow red (then orange, then white, then blue if you get it hot enough). It was glowing before, but was doing so in the "Infra Red" spectrum and you couldn't see it. The IR spectrum is called "thermographic" because in general things that are on Earth tend to emit light in those frequencies rather than visible spectra.

Old glass used to be just as transparent to infrared light as it is to visible light. But in the twentieth century they figured out that they could keep houses from losing energy by making windows that were opaque to IR but transparent in the visible spectra, and that this wouldn't bother anybody because humans couldn't see that light anyway. Of course, in Shadowrun, you have nearly 10% of the population who can see that light, and for whom looking through an IR opaque window would be like tinting the window blue. So you can bet that in Shadowrun, a lot more windows are going to be IR transparent than they are in 2005.

Now, exterior building materials are generally opaque to infra red light for much the same reason that they are opaque to other light. Letting light escape the building is bad for energy efficiency, as well as privacy. Interior building materials less so, but are still ofen opaque. Office cubicles, for example, are sometimes translucent to IR.

-Frank

just to nitpick Frank, but isnt it orange-red-blue-white?

So when, in the movies, you see thermo looking through walls... it's completely farcical, or is it just something that's not IR/thermo?

Basically, is there a way to see through walls with any manner of vision enhancement? I know that we currently have scanners that can see through/into walls (I guess by some manner of ultrasound?) but the sensor has to be physically against the wall. Is there something that works from a distance to detect things through walls, or no dice?

The problem with magical Hollywood vision is that often there's a projector component that you wouldn't get in real life. Superman's x-ray vision being the perfect example. Our x-ray scanners work by having an x-ray gun on one side of something, and the film on the other. The gun blasts the rays through the target and into the film. There are not enough x-rays just bouncing around on the middle of the street for something like that to work. (And thank God, or else we'd all be dead of cancer from that much radiation.) Ditto for the magical scopes on the magical rail-guns in Eraser that could just see through houses and skin to target a person's heart.

Infra-red vision is especially problematic for us, because we're warm-blooded. Our bodies pump out waste heat 24/7. Know what that means? We're shining beacons of infrared. Every inch of us. Even our eyes. Imagine trying to see if your eyes were glowing like flashlights. I'd kinda bet that you wouldn't see anything at all past the hellish glow that never went away, even with your eyelids shut. Thermographic vision must be magical in nature for dwarves and trolls, because it just wouldn't work naturally for warm-blooded animals. And cybernetic thermographic vision would need some sort of cooling element to keep body heat from 'contaminating' the sensor, or some way to filter out the fact that the person the sensor is in is radiating infrared light.

Millivision millimeter radar does work. I saw a demonstration of it at the local airport. I definitely see uses of it. For example one could thoroughly check Nadia Daviar...