How does ultrasound work, in game mechanics terms? Options

[Ranger]

Ultrasound is described as being "...perfect to “see” textures, calculate exact distances, and pick up things otherwise invisible to the naked eye (like people cloaked by an Invisibility spell)..." (SR4A, 333). Descriptively, this makes it sound like you can walk around with your eyes closed or in a completely dark room without any problem. It also sounds like you can detect any invisible person without a problem.

However, the Visibility Table on page 152 of SR4A includes dice pool penalties for ultrasound when you are in less-than-ideal lighting conditions, which implies that ultrasound does not let you see perfectly in total darkness, or even partial darkness for that matter, and by extension implies that you also wouldn't be able to see invisible people with perfect clarity.

So, just how well does ultrasound allow you to "see"? Can you see invisible people without making a Perception Test if they aren't otherwise trying to hide? If you can see invisible people, do you suffer any penalty to hit them in combat, including needing to use Intuition instead of Agility ("Blind Fire", SR4A, 150-151)?

[Mongoose]

Ultrasound vision is basically "radar" imaging that uses sound instead of radio waves. I tend to envision Unltrasound output as being a fairly low-res image that is mostly black and white, with some false color (or other simsense overlay) to indicate doppler shifts caused by moving objects.

This image would over-lay or be "mixed in" (as edge enhancement, etc) with your normal vision, which is why Ultrasound vision systems would work better in lit Environments than in the dark. You certainly COULD walk around with your eyes shut, or in the dark, but you'd miss out on a level of detail, and might miss certain items (ones transparent to high frequency sound, which isn't to many things) or have trouble making sense of what you see as easily as you would with your normal vision senses mixed in.

As far as detecting invisible people goes, consider this; Ultrasound can't see through glass, because noise bounces off glass pretty well. To ultravision, a window looks like a flat panel of opaque material. Same with a computer display, or poster. Holos and trid probably don't show up either, and camoflauge (unless heavily textured) and Ruthenium stealth suits would look just like normal clothing.
One "explanation" for invisibility is it basically makes you transparent, with the same index of refraction as air. Or, for a more rules based explantion, the Invisibility spell is an illusion that doesn't have any auditory component. So yeah, they are gonna stand out pretty good. I'd expect most vision systems would be specifically configured to highlight anomolies like this, so if something shows up in ultrasound but isn't there in normal vision (or vice versa) it might REALLY stick out.

[Mercer]

How do Silence spells affect ultrasound? Does it knock it out or is it a penalty based on the force or hits or what?

[Mongoose]

IIRC, a silence spell basically creates a big Ultrasound "blackout zone" for its area of effect. Ultrasound can't see anything inside that zone, but it can see that there's a big noise absorbing "wall" there. Not sure if the force of the spell / hits have any meaning for this purpose- I suppose if the Ulatrasound has a rating, you might use an opposed contest to see if / how well it can "punch through".

If you had a non-area silence spell (one that affected only an individual) it would be pretty wierd looking to ultrasound. The effect would be much like looking at somebody who reflects absolutely no light; you'd see a siloette of their shape. Would make judging distance and motion harder, and you'd be at a loss to tell what they were holding, etc. Ultrasound might be a bit better because you could judge how far away they were by pinging the distance to the ground under their feet.

[Ranger]

Thanks, Mongoose. To re-ask my final questions: would someone with ultrasound vision suffer a dice pool penalty to attack an invisible enemy? Would the character need to use the Blind Fire rule?

To answer Mercer, I would rule that a silence-type effect is the same to Ultrasound as Invisibility is to regular vision. Thus, the character with ultrasound would need to resist the Silence spell before being able to detect the other person.

[Karoline]

I'd noticed that too about how ultrasound takes lighting penalties. My guess is that the penalty represents the fact that ultrasound isn't how a person is 'used' to seeing. It can't be accounted for by low resolution, because it has good enough resolution to pick up textures, which would indicate an absurdly high resolution (less then a mm most likely).

This suggest that the difficulty is with the fact that when looking only through ultrasound (like you would in total darkness or with your eyes closed) it is different enough from what you are used to to cause a penalty. Seems like a bit of a weak excuse, because then what happens if someone uses it all the time and gets used to it, but it is the only real reason I can imagine that there would be any trouble with seeing with it.

As an added advantage on an AoE silence, you could have the ultrasound track the center of it, which might be where the mage is, and just shoot for that.

[Ranger]

...
This suggest that the difficulty is with the fact that when looking only through ultrasound (like you would in total darkness or with your eyes closed) it is different enough from what you are used to to cause a penalty. Seems like a bit of a weak excuse, because then what happens if someone uses it all the time and gets used to it, but it is the only real reason I can imagine that there would be any trouble with seeing with it.

"Weak excuse" is right. (IMG:style_emoticons/default/smile.gif) I have an adept in my game with the Enhanced Sense (Ultrasound) power, so I would think she'd be quite accustomed to using ultrasound.

Unless someone suggests a better idea, for firing at an invisible enemy, I'll go with the same penalty as firing in full darkness: a -3. I'll also skip making the character use Intuition instead of Agility.

Even though such a penalty seems odd considering how great ultrasound seems to be based on the description, I'll go with it since I don't want ultrasound to be the end-all vision type that everyone takes because it's the best of the best.

[Mongoose]

Well, at 100Khz (about what diagnostic ultrasound uses) sound has a 3mm wavelength. My impression is you can't typically build an active imaging system that offers finer resolution than the wavelength of the probing signal, but there's (calculation intensive) tricks that allow it (synthetic aperture radar does exactly that, for example) which might be practical in a Shadowrun setting. And "textures" can mean many things; you'd be able to tell office carpet from bare concrete based on how much and in what manner sound bounced off it, for example, without resorting to artificially enhanced resolutions.

The penalty for using Ultrasound in the dark (or only using ultrasound) might be appropriate even to expereinced users. The bulk of the human environment is oriented around visual cues. Echo-location simply is not equally useful, and a blanket penalty (instead of lots of situation specific ones) seems the easiest way to handle that.

A wierd tip on the textures thing- because the wavelenghts are similar to those of rather common real world physical features, its theoretically possible to construct an "ultrasound hologram". To normal vision, it might look just like a stucco wall, but hit it with the right freq of ultrasound and it bounces back a full 3d ultrasound image, or is just really confusing. If you had specially designed clothing with a very rough, sound reflective surface texture, it might be able to use this effect to confuse your ultrasound image enough that the user couldn't peg your actual location / body shape. If we actually had such senses, you might even see "paintings" done in such a fashion, the artist working in plaster with a set of "combs" with various tooth shapes / spacings. Pretty sure I read a sci-fi story once that had such an artform in it.

[Ranger]

If a person is standing behind a pillar that completely blocks line of sight to him, would someone with ultrasound vision be able to "see" him by using only ultrasound?

[Karoline]

If a person is standing behind a pillar that completely blocks line of sight to him, would someone with ultrasound vision be able to "see" him by using only ultrasound?

No, because the ultrasound can neither go around nor through the pillar. Thus the person would be quite hidden from ultrasound.

[Mongoose]

No. Not unless the pillar is made of something sound can pass through. MAYBE you could see a "mirror reflection" of what's behind the pillar off a very smooth, hard nearby wall surface.

You'd mostly just see through things you already expect noise to pass through- mesh, screens, thin hanging cloth, paper walls, etc. And even then, high frequency sound doesn't pass through stuff as easily as normal sound- that's the whole reason its good for imaging!

Just treat it like normal vision that can't see images or through windows, and you'll save your GM a lot of headachey "what if" situations.

[Ranger]

Thank you, Karoline and Mongoose. I understand a lot better how ultrasound works. Or at least how it could work in a reasonable fashion in the game.

For the record, I am the GM, which is why I'm wondering all of these things so that I know how to rule on them. (IMG:style_emoticons/default/smile.gif)

[Draco18s]

Ultrasound vision is basically "radar" imaging that uses sound instead of radio waves.

Perhaps something akin to sonar and echolocation?

[Ol' Scratch]

That's exactly what it is.

[Doc Byte]

Even though such a penalty seems odd considering how great ultrasound seems to be based on the description, I'll go with it since I don't want ultrasound to be the end-all vision type that everyone takes because it's the best of the best.

It's not the best of the best. Ultrasound becomes quite useless for tracking moving targets at distances beyond about 170 meters due to the sound velocity of 343 m/s and the signal delay.

[Draco18s]

It's not the best of the best. Ultrasound becomes quite useless for tracking moving targets at distances beyond about 170 meters due to the sound velocity of 343 m/s and the signal delay.

That's probably where the vision mods are really coming from: signal delay. At short distances things will be close to where they were, but I could still see that fractional second difference mattering when you fire a gun.

[3278]

And "textures" can mean many things; you'd be able to tell office carpet from bare concrete based on how much and in what manner sound bounced off it, for example, without resorting to artificially enhanced resolutions.

This. The detection of textures with ultrasound is not wavelength-dependent, because the diffraction of the longer wavelength pressure wave by the small details of the surface are what produces the information used to detect the texture, in the same way that a big wave hitting little rocks will produce lots of small waves, not a monolithic reflection of the large wave itself.

The penalty for using Ultrasound in the dark (or only using ultrasound) might be appropriate even to expereinced users. The bulk of the human environment is oriented around visual cues. Echo-location simply is not equally useful, and a blanket penalty (instead of lots of situation specific ones) seems the easiest way to handle that.

I would certainly agree with this assessment, provided the ultrasound were being processed as echolocation: in other words, as an auditory sense [the way the blind navigate]. However, isn't the ultrasound system - as well as the Radar system - in Shadowrun simply taking the information from the echolocation and producing a wireframe overlay which is processed visually?

I also agree with what was said upthread about using differences in visual input and ultrasound input to highlight possibly invisible objects. This could be done in "hardware" or "software," and should have some additional cost, but would quickly just become part of the standard package, as optional features tend to do.

[Karoline]

Perhaps something akin to sonar and echolocation?

Think bats, man. (IMG:style_emoticons/default/wink.gif)

[Draco18s]

Think bats, man. (IMG:style_emoticons/default/wink.gif)

My point was that sonar is a word for "like radar, but with sound."

And not just bats, but dolphins, most whales, shrews, and a few species of birds.
(Note: megabats don't have echolocation, except the genus Rousettus)

[3278]

(Note: megabats don't have echolocation, except the genus Rousettus)

...which does its echolocation in a somewhat idiosyncratic way. Rousettus has been a great asset in studying both convergent evolution and echolocation. Nice reference.

[Ascalaphus]

If you had specially designed clothing with a very rough, sound reflective surface texture, it might be able to use this effect to confuse your ultrasound image enough that the user couldn't peg your actual location / body shape.

Well, so an anti-ultrasound stealth sound is possible; either by looking confusing, or absorbing more sound than normal.

[3278]

The effects of Silence and similar spells on ultrasound used to be clearly spelled out. Is this no longer true?

[hahnsoo]

The effects of Silence and similar spells on ultrasound used to be clearly spelled out. Is this no longer true?

It looks like this was taken over by the "Sound Barrier" spell on p171 in Street Magic. I can't find a rule that allows Silence/Hush to affect Ultrasound. It might be buried somewhere. *shrugs*

Sound Barrier: "A variant of the Silence spell (p. 202, SR4), Sound Barrier creates a perimeter of silence around the area of effect (rather
than creating a mass area of silence). Those inside cannot hear outside noises but can hear sounds within the globe and vice versa. Only sounds crossing the border are affected, in the same manners as the Silence spell. This spell also affects technological devices, infrasound, and ultrasound."

Still, even using a "common sense" ruling, a mage using a Silence spell would probably show up as a blank spot in the ultrasound. The fact that there's an area that appears as a dead zone in the visual overlay might look suspicious, depending on the sophistication of the ultrasound system.

[Stumps]

Ultrasound for a metahuman naturally would probably look something like this:
http://209.85.12.231/670/83/upload/p3438696.jpg
(Original Version of the photo: http://209.85.12.231/670/83/upload/p3438699.gif )

It would probably not look like Dare Devil's interpretation (which I think many runners think of it as in some way, even without thinking of DD):
http://www.awn.com/files/imagepicker/1/hou...vil_shadoww.jpg

That said...some kind of future-tech equipment that using computed ultrasound imaging would probably look something like long-range versions of what we see today as 4D ultrasound in utero imaging:
http://www.3d-4d-ultrasounds.com/images/ga...efore-after.jpg

Basically...something that looks close to clay in shades of bronze with some really dark odd black spots where the sound isn't picking anything up quite right, and probably a little worse than the last image due to range. But if it's future-tech, it wouldn't be that much worse.

However, natural ultrasound would probably look worse and much more like the first image, but possibly with a 3 dimensional depth and feel much more like the 4D imagery (the last link).

[Brazilian_Shinob...]

I've always thought of ultrasound vision just like the screen shown on those pregnant women ultrasound device. You can see shapes, but hardly any detail.