Magical Light and Infravision

[gudmo]

What are your opinions on spells such as Light and Continual Light in regards to Infravision.

For example if some monster has only infravision (Not normal vision) do the Magical Light spells give off heat or only light.
Is it like heat = light intensity.

Another one is if beings with Dark Vision and those with the Dark Vision spell on can actually see light sources, or is the world all equally bright. I ask this because if a party is stealthing through a dungeon with continual light on and the monster has dark vision, would it see the light change ? It has dark vision and therefor I would guess that in it's eyes light and dark are equal.

[Kelly Pedersen]

Originally Posted by gudmo

For example if some monster has only infravision (Not normal vision) do the Magical Light spells give off heat or only light.
Is it like heat = light intensity.

This is ultimately going to be up to the GM, I'd say. It depends on how "realistic" you want magic to be, basically. In a completely-unrealistic setup, the light created by magic is "pure light" or something like that, totally unrelated to heat, the pure essence of illumination, and gives off no heat. In a moderately-realistic system, the light emitted could be 100% in the visual spectrum, and thus the source itself might not emit any heat, but as soon as it struck any objects, some of the light would be converted into heat, allowing a creature with infravision to spot the increased temperature. And in a fairly-realistic setting, the light source itself probably emits some wavelengths in the infrared spectrum, enough for a creature with infravision to spot it directly.

In a Dungeon Fantasy-esque game, I'd probably go with the middle option. Stupid Infravision Tricks are a genre trope in that sort of game, so giving the characters with infravision some option to spot the light source makes sense to me.

Originally Posted by gudmo

Another one is if beings with Dark Vision and those with the Dark Vision spell on can actually see light sources, or is the world all equally bright. I ask this because if a party is stealthing through a dungeon with continual light on and the monster has dark vision, would it see the light change ? It has dark vision and therefor I would guess that in it's eyes light and dark are equal.

I would rule otherwise - Dark Vision includes no notes about such problems, and the general guidelines with GURPS advantages is that they probably shouldn't seriously disadvantage you if they don't say they do. Also note that by default, Dark Vision is strictly monochrome, so the monster should be able to spot the fact that suddenly it's seeing in color.

[gudmo]

Just now bothered to read the introduction to the L&D College

These spells affect not just visible light, but also infrared and ultraviolet light. Spells that provide illumination will allow those with Infravision and Ultravision to see, while spells that block ordinary vision will also block those senses.

So in accordance to this any light spell affects any light oriented spell/advantage/disadvantage.

This would also include Dark Vision.

[malloyd]

Originally Posted by gudmo

For example if some monster has only infravision (Not normal vision) do the Magical Light spells give off heat or only light.

Another one is if beings with Dark Vision and those with the Dark Vision spell on can actually see light sources.

For Dungeon Fantasy I'd say yes and yes. After all the whole point of both magical light sources and those alternate vision modes is to let you ignore details of lighting levels.

For a setting that cared more about physics, it's a harder call - ideally you'd need the emission spectrum of the lights, the absorption spectra of the things they might be shining on, and the frequency response curves of the IR detector to answer the question about infravision, and a lot more information about how Dark Vision even works before you'd allow it into the same game as one that cared about that sort of thing.

[Hide]

Originally Posted by gudmo

What are your opinions on spells such as Light and Continual Light in regards to Infravision.

For example if some monster has only infravision (Not normal vision) do the Magical Light spells give off heat or only light. Is it like heat = light intensity.

Another one is if beings with Dark Vision and those with the Dark Vision spell on can actually see light sources, or is the world all equally bright. I ask this because if a party is stealthing through a dungeon with continual light on and the monster has dark vision, would it see the light change ? It has dark vision and therefor I would guess that in it's eyes light and dark are equal.

Oh I already had this dilemma. I will oversimplify stuff, and attempt to stick to a """scientific""" point of view...

There are 3 things which come into play when we talk about vision:

(1). Collecting stimuli
(2). Perceiving colors
(3). Adjusting to stimuli

I will focus on light as the stimuli; this means you have more than 1 way to see.

You should know that light is both "energy & matter", an exception, so to say. Everything is charged with energy, you, your computer, the floor, the ceiling, water, etc. sometimes, certain energy outputs result in what we perceive as "light we can see".

For example, the energy from the sun, is sun-light. Human eyes are adapted so we can see this kind of light (1), but we don't see just everything, just a few colors (2). And depending of the strength of this light, we adjust our eyes to collect as much light as we can (3).

If we don't have much light, we can't see and we cannot perceive much colors. Your retinas will open so you can gather more light, and your eyes will produce a certain chemical to allow you perceiving more colors. And we call this "normal vision". Normal vision is limited to a certain color spectrum or palette (this is directly related to the kind of light you can perceive).

Considering this, infra-vision is simpler.

The thing with infra-vision, is that you can perceive "other kinds of light", this is infra-red light and maybe near infra-red light (NIR).

This light is still present even if normal eyes simply cannot see it (heat-waves, NIR light, etc.). If you have infra-vision only, then you see a limited color palette, which is the colors of the infra-red spectrum (just as normal vision provides you with “normal colors”). Regardless, your eyes work almost in the same way... you need to adjust your vision to your environment in order to see and so on. It may be harder for a being with infra-vision to see under "normal light" conditions, but it's still possible… remember, you can only see certain colors with infra-vision and those colors are affected by the intensity of the light as a whole.

Finally, heat coming from your body is energy infra-vision perceives as light. Thus, you can see the prints of heat from warm subjects/objects. This might change the way you perceive the world. Some hi-tech cameras mix infra-vision with normal vision, this returns a vivid image under low-light environments. Let's imagine this is infra-vision with normal vision.

Dark-vision

Well, Dark-Vision is vision working without light. Depending on the approach, this could be a cinematic skill, IMO. As the book says: "you can use other means other than light to see”… I told you there are several ways to "collect light", so let’s part from this.

Think of Daredevil, the super hero. Basically, he employs sounds instead of light... Sound rebounds until it reaches his ears, and his super-senses allow him to shape the outside world with the power of his mind. His vision is near perfect, but limited to the sounds he perceive, and messing with the sound “dazzles” him. In this sense, he won’t be able to “see” what he cannot hear.

If we stick to the explanation (using light as matter), I would say that Dark Vision allows you to perceive matter as light and when you have +Color Vision, then it gives you color vision under the color spectrum of normal vision. To me, this means you cannot see infra-red or ultra-violet light, etc. but you can see everything else, as if there was sunlight because all matter in this world has an energy print.

Now I can reply to your questions, and this is my opinion.

Regardless of your type of vision you can see as much you can perceive. Since this is dungeon fantasy, I would say that “special types of vision” allow you to see as much as you can see with normal vision if your vision is an advantage. So the world is equally bright.

Also if you have several types of vision, they stack and provide you with more details of your surroundings. And, if your vision is a spell, I would say it lets you see within the specs of your spell. If there are no limitations, then it is the same as if it was an advantage.

When you cast a spell for infra-vision and make infrared light, you are creating a source of light and light. And if you don't hide it (using Obscure, for example), those with the proper vision will see it.

Finally, I am OK treating all visions in the sense normal vision works (more or less). I employ my penalty table from the basic book, and add other modifiers if the PCs or the NPCs are dazzled or obstructed:

Let’s assume normal vision itself is kind of passive but complex and convenient… You need a source of light, this light rebounds in objects… such objects reflect “residual light” which you perceive as color as soon as they reach your eyes. And all of this happens continuously at the speed of light! If all of sudden, you pass from a low light environment, to a high light environment, your eyes will be hurt. This is the effect of being dazzled. Basically, the chemicals produced in your eyes to see colors under a low light environment burns, and everything turns white (roughly speaking, you have a lot of light-sensitive chemicals that mix into white). If the opposite happens, then you cannot see properly because your retina is almost closed and your eyes have not produced enough chemicals to perceive colors.

In GURPS, if you don't want to suffer from this effects, you buy "Protected Sense: Vision". Regarding your depth of vision and “image definition” but put very simply: The reason you can or cannot see big or small objects or objects from afar is because light coming from other objects overlaps and you cannot gather enough light to see all the light sources. Telescopes concentrate light, and that’s the way you can see stuff from afar. If you have good eyes, then you can gather light more efficiently and tell more details about the stuff you see.

If you get technical, you will need other limitations that you will need to keep in check because you will have to think whether or not this or that interferes with your vision, whether or not you need to apply a penalty to this NPC or that PC… and so on…

For example… what happens if there’s no light? Basically you need another stimuli, if there are no stimuli, you cannot see. And light is the fastest stimuli around, so other stimuli will be slower and perhaps weaker. If we think about sounds, small sounds dissipate as they travel and also other sounds might interfere with it... Let’s imagine you have a Dark Elf with sonar-dark-vision… Everybody relies in your advantage because you’ve been told the enemy will arrive when it’s nightly… at a certain point your dark vision won’t provide you with the image of their ship arriving from afar because, maybe, the reach of your sonar won’t’ do. Or maybe you think it is a whale (Surprise!)… At such point I would feel very sad for you… Sometimes PCs think they will get a very cool ability, but reality serves another thing.

Hope this helps,
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