Infravision

[Flyspeck23]

Right -- but mirrors don't work in darkness. They work by reflecting light.

Eyes do work pretty much like mirrors on that regard, nevertheless darkvision helps seeing in the dark. So what?

I'm just thinking that darkvision was introduced in part because there seemed to be so many differing interpretations of infravision. If there's more than one interpretation of what darkvision can do, then what's exactly the point?

It is more straight forward. At least in my group.

that's from the entry on dwarves, right? Well, the 3.5 DMG entry on darkvision does not have the phrase "otherwise just like normal sight".

But it doesn't contradict it either.

Reading is debatable, admittedly. I personally prefer the idea that the physical shapes of objects are revealed in black and white, but you recieve no information as to their coloration - along the lines of radar or sonar information, rendered as a greyscale image. Meaning you could tell the thing is a book by the shape, but the color information differentiating the writing from the page is lost. Gives dwarves a good reason to like all that carving and engraving, I think

Then take a look at the sample "Mind Flayer in darkvision" illustration. Clearly there are greyscales with many different scales, indicating a relation between the color and the greyscale.
One might introduce books in her campaign which can't be read with darkvision because the color of the page and the color of the ink would relate to a pretty similar greyscale, but the books would've been made that way, it wouldn't be a default "feature".
Your idea of a "radar sense" is appealing... but would lead to similar problems as infravision: characters could do things with it they shouldn't accomplish that way.

As for mirrors - well, they work by reflecting light. Darkvision functions when there's no light. How on Oerth can Darkvision see reflected light that isn't there?

How on Oerth can there even be such a thing as darkvision?


[Edit: Mixed up colors. Sorry. I guess it wouldn't be a problem if we all had darkvision... guess I shouldn't have said that...]

 

[Umbran]

Then take a look at the sample "Mind Flayer in darkvision" illustration.

Sorry, but I'm not about to use flavor-illustrations as a guide to how I think the rules should work. I have exactly zero confidence that those things were vetted for rules-correctness. If I go by such illustrations, halflings have brown noses, beholders have 18 eye-stalks

Your idea of a "radar sense" is appealing... but would lead to similar problems as infravision: characters could do things with it they shouldn't accomplish that way.

Well, you'll note that I did not say that it *works* like "radar sense". I merely used that as a similie to give an idea of the image formed. I could also have said, "along the lines of seeing the scene as if it were a sculpture made from a plaster cast (which preserves form, but not surface color or original lighting conditions)", and gotten much the same idea across.

 

[Ferret]

Heatvision-You can see the heat inside people, not anything else.

Munchkin tight.

 

[tarchon]

Care to be more specific? Which arguments do you think don't hold water?

It's really the fundamental argument that fails, the idea that infravision doesn't work because of its mechanical complexity. Most of the examples he gives of supposed interpretive difficulty apply equally well to Darkvision, but I don't really see them as being that difficult to resolve.

For example:
"Displacement: Shouldn't infravision negate this, too? Even if the target's radiating heat is displaced, the target is also heating the air and ground, which shouldn't be displaced."

Thermally emitted light is still light. A torch in hand doesn't have any weird effects on <i>Displacement</I> with normal sight, so if your hand <b>is</b> the torch, it's not any different. All spells based on illusion should not be affected one iota by viewing the scene in the infrared. Light is light. Most of the arguments miss this simple fact, which makes the interpretation obvious if one keeps it in mind.

The physical explanation of thermal imaging misses the important points too, and the whole thing about the "air curtain" is just wrong. A heat plume certainly does form over warm bodies, and it can be detected from thermal emission (though usually you detect it by other means), but the thermal emissivity of air is so low that the emission from the body overwhelms the air plume signal by orders of magnitude. The analogy to heat rippling is false as well, since the heat rippling effect comes from pronounced density variations in turbulent rising hot air.

There are two simple facts that make thermal vision in humans and similar creatures highly unworkable physically:
* The background light from the retina, eyeball, skull etc. will be thousands if not millions of times more intense than the image of a distant object falling on the retina.
* Aqueous tissues are quite absorptive in the middle and far infrared. This means first that the eyeball as a thermal IR optic works as well as a ball filled with rootbeer and second that the eyeball is a powerful thermal IR emitter itself. It would be like trying to look at something through a mass of luminescent gel.

So, I'd say it has the right conclusion for all the wrong reasons.

 

[tarchon]

I can see 4 basic ways to do it:

1. Thermal vision - images based on thermal emission
+ Based on real physics, so if you know real physics, it's easy to figure out what it will do
- Can't work for hot or warm-blooded organisms or organisms with water-based eyeballs of any significant thickness

2. "Darkvision" - arbitrary magic vision
+ You can define it to do what you want it to do
- Hard to interpret in unusual situations since it doesn't have any clear underlying theory - calls for a lot of fiat rulings

3. Life sense - you can detect living things
+ Fairly easy to interpret in most cases
- Hard to see how it would be that useful for underground-dwellers

4. Active near infrared vision
+ Easy to interpret based on real life experience. Your eyes are flashlights that emit light only you and others like you can see.
- Begs the question: "why don't their eyes just emit visible light?"

 

[Gnimish88]

Out of curiousity, why not just assume that seeing with darkvision is pretty much like looking at a black and white movie? I realize that there is visible light issues regarding mirrors and such, but, since this is magic, why not?

 

[dcas]

Out of curiousity, why not just assume that seeing with darkvision is pretty much like looking at a black and white movie? I realize that there is visible light issues regarding mirrors and such, but, since this is magic, why not?

But it is "magic"? Dwarves have darkvision and they aren't magical beings. I would argue that "darkvision" is a natural ability that can be replicated by magic (the darkvision spell).

I never did like the explanation that "it's magic." If that's the explanation then may as well stick with infravision.

 

[Umbran]

Out of curiousity, why not just assume that seeing with darkvision is pretty much like looking at a black and white movie?

To be honest, because that's so simple it's boring. I'd personally prefer an interpretation that adds minimal complexity, while still making Darkvision slightly different in a flavorful manner.

 

[Gnimish88]

To be honest, because that's so simple it's boring. I'd personally prefer an interpretation that adds minimal complexity, while still making Darkvision slightly different in a flavorful manner.

Hmm... Well, if you really want more complexity...

Frankly, I would rather have such a basic portion of the game well spelled out and leave the complexity for the magic system. ;-)

The only real sticking points that seem to exist with the mechanics of darkvision is how transparent/reflective surfaces work with it and if you can read with it.

As far as transparent/reflective surfaces, if we use the physics explaination of darkvision, the only real question I see is whether or not the wavelength of radiation that darkvision uses is affected by the surface in question. I am afraid I don't have the background in physics to argue much on this point.

As for reading, my understanding of color is that we percieve it due to a color's absorbant qualities regarding different wavelengths of radiation. It seems to me, if that is the case, that you will still have some ability to distinguish between a highly reflective surface (pale paper) and a highly absorbant colored medium (black ink) using darkvision.

If you want to go by the magic explaination, then you can toss all of that out the window (assuming you can see through it) and simply say what it does and doesn't do.

 

[Ferret]

I had always assumed Dark vision picked up on lines. Also how did ultravision work? And thinking about Ultravision, why not have them (underroundy folks) have a ultrasound radar, that picks up on a sound only created in the underdark. It's dark ennough to not matter for invisibility, you can silence it for a "darkness" spell, clocks can ring with it etc.