Topic: A couple of queries re Invisibility

[Pat]

1) With Invisibility it says that the target can only be detected in certain ways or methods. One of these listed was body heat. I was wondering, if a character has Dark Vision could he "see" an invisible person? As far as I am aware, Dark Vision uses surrounding heat to determine shapes and surrounds so would a person with this ability be able to view into the invisible spectrum without penalty to attacks etc?

2) I'm assuming that the blind fighting skill would also remove the -100 to attack, if high enough, against foes using Invisibility. Is this correct? I'm also assuming that a person using this skil must be aware that an invisible person is nearby. (i.e. has been detected)

3) If Dark Vision can detect invisible subjects, would it also work for the spell Nightvision scaled to Improved Vision?

[Thom @ ICE]

Chapter 9 (page 75) has a section on invisibility, but to answer your specific questions (noting that this is my personl interpretation) -

1 - The description of Dark Vision has no mention of being impacted from heat of a torch or campfire, therefore I don't consider it as Infravision. I would not permit it to see Invisible beings.  In my interpretation it is simply like walking into a dark night club... it appears pitch black, but your eyes adjust to allow you to see pretty comfortably.  In the case of Dark Vision, the adjustment goes far beyond what humans are capable of, but it is still not related to body heat.

2 - Blind fighting will work against Invisibility, and I would also allow it as a Light Maneuver base (-80 instead of -100) because in the case of Invisibility only the target is invisble, while in Blind Fighting everything is. This allows the combatant some ability to expect certain moves and maneuvers by his foe or use walls or objects to block other moves.

3 - As I indicated Dark Vision could not, neither could Nightvision.

[Pat]

Thanks for the clarification. What you've said makes perfect sense,

[Thom @ ICE]

Now  that's something I don't hear often..... Thanks!

[RandalThor]

Now  that's something I don't hear often..... Thanks!

Yeah?!? Don't get cocky.

[RandalThor]

Now  that's something I don't hear often..... Thanks!

Yeah?!? Don't get cocky.

Holy-moly! I totally thought it would change it to Roostery!!

[GrumpyOldFart]

As long as it works for you, good... personally, it doesn't work for me. Nightvision provides for operating in the light of a full moon as if it were full daylight, and starlight only as being roughly equivalent to twilight, but it also notes that a character with nightvision is just as blind in "total darkness" as anyone else.

To me, that doesn't say your eyes have superior light gathering capabilities, it says your eyes are capable of detecting something outside of the "visual" RF spectrum... and the most common place to find "total darkness" in a fantasy RPG is underground, so you can't really assume vision in the UV range either.

That doesn't leave much. Pretty much the only choices left are IR vision or something that, in the sense of mapping incoming RF, isn't "vision" at all, it would have to detect a non-RF energy form.

[Thom @ ICE]

Actually, to me that says exactly that Night Vision grants the individual the ability to gather reflective light better than most people since they can act in the night with minimal light as well as someone in full daylight.

The Dark Vision is the tough one to explain....
If the tunnel is entirely dark (no light at all) then how can the individual see... None of the descriptions comment in any way about heat, infravision, ultravision, etc. The actual description refers to seeing by torch light without any mention of heat impacting it, which would greatly effect infravision.  And UV would not work underground either....

Effectively it is the ability to "see" in the dark without any other explanation.  You have four options -
1 - Assume it is Infravision and the example is just poorly written.
2 - Assume it is some form of Radar Vision (think Daredevil from Marvel Comics)
3 - Assume it is some special vision that does not have a scientific equivalent in our world
4 - Go with something else that I can't conceive of, but you may be able to offer up.

[GrumpyOldFart]

Exactly. Nightvision sounds like better light gathering, but Darkvision pretty much has to either be:

1. IR based.

2. Require the person seeing to be outputting the frequency of RF his vision "sees" (as radar does), or

3. A method of mapping some form of energy other than RF.

The thing that makes it really difficult to make sense of is that "Greater Darkvision" has a range of 20' or so in total darkness and a cost of 30 DPs. "Heat Vision" allows the character to see the world as a temperature mosaic, registering differences of a fraction of a degree, no maximum range given... for 25 DPs. I'd think that would work in total darkness as well, except in an environment at 0 degrees Kelvin, yet it's 5 DPs cheaper than "Greater Darkvision" with a range of only 20'.

 

[Thom @ ICE]

Now you are jumping to HARP SF.... And referencing the pre-final release version, because to the best of my knowledge no official HARP product included Heat Vision (though it may have been in one of the unofficial products since I didn't check all of those).

The final version of HARP SF does include Heat Vision, but it does not include Dark Vision.  Instead it includes a number of senses that are not found in HARP (water, heat, telescopic, electromagnetic, motion sensing, and still has night vision.... I may have missed a few).  This was part of the clean-up when the product had the playtesting applied by GCP.

Regardless, I would still hold to the idea that Heat Vision has limitations compared to the wide-open concept that Dark Vision portrays of sight without light or any other energy being perceived.  I personally like the "Radar" version of Dark Vision as it should be effective, even in utter darkness and would perceive invisibility (thus justifying the hefty price tag).

[GrumpyOldFart]

My only problem with "radar vision" is that it requires a "transmitter", in other words the body has to provide a source of that energy to be reflected back to the sensory organs.

Okay, so what, right? So that means that anyone else with the same sense can see you "transmitting" at roughly twice the distance you can see your own reflected transmission. It's the same reason why all sailors like passive sonar and only use active sonar when they have no other options.

"Without light or any other energy being perceived"? What is sensed then, if not an energy form?

[providence13]

Maybe it's gamma correction. 
http://en.wikipedia.org/wiki/Gamma_correction

[NicholasHMCaldwell]

Yup, Dark Vision was the one that looked suspiciously magical to me which is why I went with a more scientific "Heat Vision" for HARP SF and removed Darkvision from HARP SF.

Best wishes,
Nicholas

[Pat]

It could be that "Dark Vision" produces its own light source. By "light source" I mean a form of radiation or "light" that can not be detected within normal vision spectrums. This means that you need to have the skill to be able to detect and effectively use this energy.

I'm just assuming (since it's not heat based and there isn't any necessity to have any actual light source present for Dark Vision to work) that it could be possible for the Dark Vision user to be the source of the light as part of the skill. If the light is only detectable by Dark Vision users, it would remain undetected to all others.

Just a thought to get around how to handle Dark Vision......

[GrumpyOldFart]

It could be that "Dark Vision" produces its own light source. By "light source" I mean a form of radiation or "light" that can not be detected within normal vision spectrums. This means that you need to have the skill to be able to detect and effectively use this energy.

That was the thought behind "radar vision", that the body not only has a sensor in that range, but also a transmitter or source in that range. But once again, you run up against the problem of your target (if he also has Darkvision) being able to see your source at twice the distance you can see the reflection of your source returning from him, in the same way someone in darkness can see a torch much farther than the person holding it can see the reflected torchlight off his target.

Gamma correction helps with processing incoming energy, but "total darkness" implies a complete absence of incoming energy in most RF frequencies. Get more than 100' below ground and about the only ambient energy sources are heat, IR, and gamma radiation from radioactive decay. RF at the high frequency end, such as X rays and gamma rays, carries so much energy per individual photon that you'd reach a stage harmful to living tissue before you'd get enough photon density to generate a complete image (I've had this discussion before which is why I remember all this, I'm actually not an optics, radar or RF expert.)

[Pat]

It could be that "Dark Vision" produces its own light source. By "light source" I mean a form of radiation or "light" that can not be detected within normal vision spectrums. This means that you need to have the skill to be able to detect and effectively use this energy.

That was the thought behind "radar vision", that the body not only has a sensor in that range, but also a transmitter or source in that range. But once again, you run up against the problem of your target (if he also has Darkvision) being able to see your source at twice the distance you can see the reflection of your source returning from him, in the same way someone in darkness can see a torch much farther than the person holding it can see the reflected torchlight off his target.

My thought was that if 2 characters had Dark Vision then they would be self cancelling as they would both be producing the energy required. By this I mean that a character with Dark Vision would not effectively "see" anothers Dark Vision energy because the second character is producing his own visual energy which would over ride the first.

Gamma correction helps with processing incoming energy, but "total darkness" implies a complete absence of incoming energy in most RF frequencies. Get more than 100' below ground and about the only ambient energy sources are heat, IR, and gamma radiation from radioactive decay. RF at the high frequency end, such as X rays and gamma rays, carries so much energy per individual photon that you'd reach a stage harmful to living tissue before you'd get enough photon density to generate a complete image (I've had this discussion before which is why I remember all this, I'm actually not an optics, radar or RF expert.)

I would also theorise that the energy produced to create this feat may not be scientifically based. Rather than heat, IR, gamma etc it could be a magical form of energy that is granted through the Dark Vision skill. When in doubt, blame magic. 

[GrumpyOldFart]

My thought was that if 2 characters had Dark Vision then they would be self cancelling as they would both be producing the energy required. By this I mean that a character with Dark Vision would not effectively "see" anothers Dark Vision energy because the second character is producing his own visual energy which would over ride the first.

Whatever energy source you have for your senses to see the reflection of has to be fairly well hidden from your senses, otherwise the original source will blind you from seeing the reflected energy, in the same way you can't see anything the torch lights up without moving the torch out of the way.

But to continue the analogy, if someone else with a torch walks away from you, even after they are outside the radius lit by your own torch you can still see their torch and part of the area it lights. Long after they are too far away to see anything lit by their torch, you can still see the torch itself, even over the light of the torch in your hand.

I would also theorise that the energy produced to create this feat may not be scientifically based. Rather than heat, IR, gamma etc it could be a magical form of energy that is granted through the Dark Vision skill. When in doubt, blame magic. 

Which is what I meant by

3. A method of mapping some form of energy other than RF.

It may be "magical" energy... it may be magnetic fields, or gravity gradients, I don't know. But it wouldn't be "vision" in the sense of mapping incoming RF energy, so there would be no reason to expect it to follow the same rules.

[Pat]

Whatever energy source you have for your senses to see the reflection of has to be fairly well hidden from your senses, otherwise the original source will blind you from seeing the reflected energy, in the same way you can't see anything the torch lights up without moving the torch out of the way.

Possibly yes, however, the energy source does not necessarily have to be hidden from your senses. It could be as simple as the energy produced to "sense" your surrounds is reflected back along a different wavelength or energy signature. This would avoid any blinding affects as one part of your brain (eyes whatever) produces the identification energy while the reflection is, on another wavelength or energy band etc, is interpreted by another part of the brain.

But to continue the analogy, if someone else with a torch walks away from you, even after they are outside the radius lit by your own torch you can still see their torch and part of the area it lights. Long after they are too far away to see anything lit by their torch, you can still see the torch itself, even over the light of the torch in your hand.

How about this....What if the energy used doesn't conform to all laws of light? For instance "The angle of reflection is equal to the angle of incidence." What if the energy, instead of reflecting as per the laws of light, only reflects back to the users Dark Vision operator? This would mean that it couldn't be intercepted by other Dark Vision characters. (Mind you this does make one skill rather involved.)

Which is what I meant by

It may be "magical" energy... it may be magnetic fields, or gravity gradients, I don't know. But it wouldn't be "vision" in the sense of mapping incoming RF energy, so there would be no reason to expect it to follow the same rules.

Good pont.

[RandalThor]

My take on this is that nightvision is being able to take in more light so that less is needed. Darkvision, on the other hand, is an ability to see without a traditional light source, because of magic. Maybe it is a magical-vision, sort of like infravision, only seeing the natural magical emanations that everything (except a very few things) gives off. Either that, or it is sort of Hyper spectral vision that runs the gamut of the spectrum, merging it all to form a combined image - they are not able to switch between the types (infra, ultra, gamma, etc..), it is all one image to them.

[GrumpyOldFart]

Darkvision, on the other hand, is an ability to see without a traditional light source, because of magic. Maybe it is a magical-vision, sort of like infravision, only seeing the natural magical emanations that everything (except a very few things) gives off.

I'm okay with that, but the question arises...

...does it supersede the Sense Magic talent? I mean, if the energy it maps is local magic flow you'd think so, huh?

Either that, or it is sort of Hyper spectral vision that runs the gamut of the spectrum, merging it all to form a combined image - they are not able to switch between the types (infra, ultra, gamma, etc..), it is all one image to them.

I'm okay with that too, but when you're so far underground there's nothing but IR, it's still infravision for all practical purposes.