The rules are described in the PC's race's traits.
e.g for Elves
Accustomed to twilit forests and the night sky, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.
for Dwarves, it is:
Accustomed to life underground, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.
You basically ignore dim light, but in darkness you have disadvantage on perception checks that use vision and can't see color.
That is it. Pretty simple.
Creatures without darkvision have disadvantage on perception checks that rely on sight in dim light, but can still see color, but are blinded in darkness.
The rules for Darkvision are in the Vision and Light rules of Chapter 9 of the PHB and are repeated for each race that has it.
"Darkvision
Many creatures in fantasy gaming worlds, especially those that dwell underground, have darkvision. Within a specified range, a creature with darkvision can see in dim light as if it were bright light and in darkness as if it were dim light, so areas of darkness are only lightly obscured as far as that creature is concerned. However, the creature can’t discern color in that darkness, only shades of gray."
In the same section:
"A given area might be lightly or heavily obscured. In a lightly obscured area, such as dim light, patchy fog, or moderate foliage, creatures have disadvantage on Wisdom (Perception) checks that rely on sight."
Also in the same section:
"Dim light, also called shadows, creates a lightly obscured area. An area of dim light is usually a boundary between a source of bright light, such as a torch, and surrounding darkness. The soft light of twilight and dawn also counts as dim light. A particularly brilliant full moon might bathe the land in dim light."
Combining these: A creature with Darkvision sees darkness as if it was dim light. Dim light is a lightly obscured area. When trying to see something in a lightly obscured area, creatures have disadvantage on perception checks that rely on sight.
These also have interactions with other rules like the Skulker feat:
---
Skulker
Prerequisite: Dexterity 13 or higher
You are expert at slinking through shadows. You gain the following benefits:
You can try to hide when you are lightly obscured from the creature from which you are hiding.
When you are hidden from a creature and miss it with a ranged weapon attack, making the attack doesn’t reveal your position.
Dim light doesn’t impose disadvantage on your Wisdom (Perception) checks relying on sight.
---
A creature using darkvision to see in darkness views dim light which is a lightly obscured area. This allows any creature with the Skulker feat to take the hide action even if they can be seen in the darkness because the area is lightly obscured to the creature using darkvision.
Another example could be the Wood Elf feature:
"Mask of the Wild. You can attempt to hide even when you are only lightly obscured by foliage, heavy rain, falling snow, mist, and other natural phenomena."
It depends on whether the DM considers darkness to be a natural phenomena. Personally, I would since darkness is a pretty natural phenomena and so a Wood Elf should be able to take the hide action in a dark area when trying to hide from creatures with darkvision.
I have recently become aware that we have been using darkvision wrong and want to fix this oversight.
Where in the source material is a breakdown of darkvision, and how it affects PCs in regards to vision, perception, etc(ie dice rolls, combat, etc).
Thank you,
Evan
The others covered this pretty ok, but it's worth noting that the core vision rules are a mess (some rules are missing, some contradict other rules, and some are just deeply confusing), so covering how darkvision modifies visibility may be insufficient for your needs if whatever is going on with how you've been messing up darkvision is connected to getting visibility itself wrong.
By way of my favorite example: the rulebook unequivocally states that darkness and opaque fog work the same way in-game, but because this is antithetical to how visibility works in the real world, many DMs (including me) house-rule this. It's not terribly useful exploring how darkvision modifies visibility in darkness until you've first committed to an answer on whether or not you actually want your darkness to behave like opaque fog.
I have recently become aware that we have been using darkvision wrong and want to fix this oversight.
Where in the source material is a breakdown of darkvision, and how it affects PCs in regards to vision, perception, etc(ie dice rolls, combat, etc).
Thank you,
Evan
The others covered this pretty ok, but it's worth noting that the core vision rules are a mess (some rules are missing, some contradict other rules, and some are just deeply confusing), so covering how darkvision modifies visibility may be insufficient for your needs if whatever is going on with how you've been messing up darkvision is connected to getting visibility itself wrong.
By way of my favorite example: the rulebook unequivocally states that darkness and opaque fog work the same way in-game, but because this is antithetical to how visibility works in the real world, many DMs (including me) house-rule this. It's not terribly useful exploring how darkvision modifies visibility in darkness until you've first committed to an answer on whether or not you actually want your darkness to behave like opaque fog.
I agree the rules for heavily obscured are broken. They really need to treat darkness, fog and foliage differently.
However, as far as darkvision goes - darkvision turns darkness into a lightly obscured area and has no effect on seeing in fog. So dealing with darkvision and darkness (even magical darkness since the spell says that darkvision can't see through it), doesn't really require resolving the issue with heavily obscured areas since those only apply when trying to view them with normal vision or viewing things outside of the range of darkvision. Inside darkvision range, darkness is a shadowy dimly lit region considered to be lightly obscured which prevents the issues with heavily obscured areas from coming up.
I agree the rules for heavily obscured are broken. They really need to treat darkness, fog and foliage differently.
However, as far as darkvision goes - darkvision turns darkness into a lightly obscured area and has no effect on seeing in fog. So dealing with darkvision and darkness (even magical darkness since the spell says that darkvision can't see through it), doesn't really require resolving the issue with heavily obscured areas since those only apply when trying to view them with normal vision or viewing things outside of the range of darkvision. Inside darkvision range, darkness is a shadowy dimly lit region considered to be lightly obscured which prevents the issues with heavily obscured areas from coming up.
Two more examples:
There's no actual RAW basis for Elven Darkvision not stacking with itself, turning Darkness within X feet (for most elves, 60) into Dim Light and then the Dim Light into Bright Light. We play as though Darkvision doesn't stack with itself but Skulker does stack with Darkvision by universal consensus, not because the RAW says so. I include this here because Darkvision has two definitions which don't agree: the general definition only upgrades Darkness to Dim, while every single racial version (including Elves) also upgrades Dim to Bright, and for no RAW reason whatsoever, we don't let the two racial rules stack with each other while allowing Skulker to stack freely.
Unlike Darkness, which works exactly like opaque fog, Dim Light, per RAW, only matters when the observer is inside it: you don't check the lighting conditions of the observed. I've literally never heard of anyone actually obeying this, because it is so very stupid: it means that when our Elf (with, presumably, non-stacking Darkvision) observes a creature while the Elf is in Dim Light but the creature is in Darkness, there is no Disadvantage, because the Elf's Dim Light counts as Bright (i.e. no relevance) and the creature's Darkness counts as Dim, which simply doesn't apply Disadvantage to the observer.
All comes down to what OP intends. Here's how I rule at my table, with annotations where I know at least a substantial minority of DMs disagree with me:
The definition of Darkvision is that it upgrades the observed's lighting conditions 1 step (Darkness -> Dim or Dim->Bright but not both) while the observed is within range.
Darkness and Heavy Fog work differently, which means there are two distinct kinds of Heavily Obscured: Darkness only checks the lighting conditions of the observed, while Heavy Fog blocks LOS in the same way as a wall (but both block LOS when they apply).
Per the text of Darkness, that particular spell and any spell with similar wording does work like Heavy Fog when the observer has Darkvision.
Other DMs and I disagree on what happens when an observer lacks Darkvision, but I have it work exactly the same way, like Heavy Fog.
Dim Light and Light Fog work differently, which means there are two distinct kinds of Lightly Obscured: both apply Disadvantage on an observer. Dim Light only cares about the lighting condition of the observed, while Light Fog is like wall: any of it between the observer and the observed (including in either one's grid space) causes Disadvantage.
Note that Darkness and Dim Light work like each other just to different degrees, and Heavy and Light Fog work like each other, just to different degrees, while lighting conditions and fog conditions do not work like each other.
Note that the only one of these four that works like it does RAW is Heavy Fog, and I have entirely abandoned the RAW on Lightly Obscured - I have no mechanics where conditions you are in affect you differently from conditions between you and the observed.
I agree the rules for heavily obscured are broken. They really need to treat darkness, fog and foliage differently.
However, as far as darkvision goes - darkvision turns darkness into a lightly obscured area and has no effect on seeing in fog. So dealing with darkvision and darkness (even magical darkness since the spell says that darkvision can't see through it), doesn't really require resolving the issue with heavily obscured areas since those only apply when trying to view them with normal vision or viewing things outside of the range of darkvision. Inside darkvision range, darkness is a shadowy dimly lit region considered to be lightly obscured which prevents the issues with heavily obscured areas from coming up.
Two more examples:
There's no actual RAW basis for Elven Darkvision not stacking with itself, turning Darkness within X feet (for most elves, 60) into Dim Light and then the Dim Light into Bright Light. We play as though Darkvision doesn't stack with itself but Skulker does stack with Darkvision by universal consensus, not because the RAW says so. I include this here because Darkvision has two definitions which don't agree: the general definition only upgrades Darkness to Dim, while every single racial version (including Elves) also upgrades Dim to Bright, and for no RAW reason whatsoever, we don't let the two racial rules stack with each other while allowing Skulker to stack freely.
Doesn't this get into the whole question of perception vs reality that someone seems to be arguing about endlessly in another thread?
Perceiving darkness as dim light doesn't change the fact that the creature is still surrounded by darkness. Darkvision lets the creature perceive darkness as dim light. It doesn't change the lighting to dim light. Similarly darkvision allows a creature to perceive dim light as bright light. It doesn't change the external condition to bright light.
From the Elf traits:
"Darkvision. Accustomed to twilit forests and the night sky, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray."
The "as if" is significant since this means it does not change the external lighting (which makes sense) so there is no way it can stack with itself since the external condition is either bright light, dim light or darkness and darkvision only triggers off the actual lighting not how it is perceived. Darkness and dim light are specific game terms that are defined in the vision section of the rules.
Unlike Darkness, which works exactly like opaque fog, Dim Light, per RAW, only matters when the observer is inside it: you don't check the lighting conditions of the observed. I've literally never heard of anyone actually obeying this, because it is so very stupid: it means that when our Elf (with, presumably, non-stacking Darkvision) observes a creature while the Elf is in Dim Light but the creature is in Darkness, there is no Disadvantage, because the Elf's Dim Light counts as Bright (i.e. no relevance) and the creature's Darkness counts as Dim, which simply doesn't apply Disadvantage to the observer.
I think what you are trying to get at here is the issue with the rules that we have already pointed out as making no sense so I am not sure why bring up an example using it. Most DMs house rule darkness and light to work how we think it should work and not the way the rules are written. As written, darkness by itself is a heavily obscured area so you can't see through it to a lighted region outside the darkness. Of course that makes no sense for most people and as a result most people house rule it.
However, since we already agreed that this makes no sense and that usually DMs house rule it so that a creature IN darkness CAN see a lighted area through the darkness then we can either discuss how the broken RAW would interpret it or how the DM might houserule it but trying to create an example in terms of understanding darkvision isn't effective since the issue has to do with seeing in darkness when a creature does not have darkvision.
In your example, if both creatures have darkvision, there is no issue since they can both see each other no matter what the lighting conditions. If the creature in the light has darkvision and the creature in the darkness does not then RAW the creature in the darkness can't see the creature in the lighted area but the creature in the lighted area with darkvision can see the creature in the darkness. Clearly this doesn't make any sense which is why most DMs run it more consistent with the real world and ignore the rules (which is exactly what a D&D DM should do when there is a rule whose interpretation is ambiguous).
All comes down to what OP intends. Here's how I rule at my table, with annotations where I know at least a substantial minority of DMs disagree with me:
The definition of Darkvision is that it upgrades the observed's lighting conditions 1 step (Darkness -> Dim or Dim->Bright but not both) while the observed is within range.
Darkness and Heavy Fog work differently, which means there are two distinct kinds of Heavily Obscured: Darkness only checks the lighting conditions of the observed, while Heavy Fog blocks LOS in the same way as a wall (but both block LOS when they apply).
Per the text of Darkness, that particular spell and any spell with similar wording does work like Heavy Fog when the observer has Darkvision.
Other DMs and I disagree on what happens when an observer lacks Darkvision, but I have it work exactly the same way, like Heavy Fog.
Dim Light and Light Fog work differently, which means there are two distinct kinds of Lightly Obscured: both apply Disadvantage on an observer. Dim Light only cares about the lighting condition of the observed, while Light Fog is like wall: any of it between the observer and the observed (including in either one's grid space) causes Disadvantage.
Note that Darkness and Dim Light work like each other just to different degrees, and Heavy and Light Fog work like each other, just to different degrees, while lighting conditions and fog conditions do not work like each other.
Note that the only one of these four that works like it does RAW is Heavy Fog, and I have entirely abandoned the RAW on Lightly Obscured - I have no mechanics where conditions you are in affect you differently from conditions between you and the observed.
In terms of lightly obscured - do you mean Disadvantage on perception checks relying on sight (you just say Disadvantage so I wasn't sure)? RAW, lightly obscured has no effect on attack rolls.
In terms of what I actually play with, I think I use rules pretty much identical to the ones you do (including treating magical darkness as a heavily obscured area) though I had not considered the case of light fog (though it makes sense), as would light foliage, in terms of causing a lightly obscured area. I also agree with viewing an area through an area of light fog or light foliage would be treated as lightly obscured as well since that also makes sense (whereas viewing an area of light through an area of darkness (whether with darkvision or not) would not be similarly obstructed).
Yep, the rules miss the difference between obscurement you can see though (normal darkness) and obscurement you can't see through (fog, foliage). This means that there is no clarity over which type magical darkness is (the "vantablack vs inkblot" discussion).
My attempt to simplify it.
To see an object or person, you only need to consider two factors.
(1) Is there any obscurement between you and the object or person? Yes: You can't see them. No: Go to question 2.
(2) What is the level of light where the object or person is? Bright: You can see them clearly. Dim: You can see them dimly - you have disadvantage on Wisdom (Perception) checks. Dark: You can't see them.
If you have darkvision and they are in range of it then the answers to question 2 become: Bright: You can see them clearly. Dim: You can see them clearly. Dark: You can see them dimly - you have disadvantage on Wisdom (Perception) checks and you can't see colours.
So from what I can tell no one has been using Darkvision incorrectly?
Because if Darkvision is Dim Light and Dim Light is Lightly Obscured and Lightly Obscured is just Disadvantage on Wisdom (Perception) checks only, then what are people getting wrong?
PCs and NPCs can still attack or cast spells as normal but detecting a stealthed enemy or a hidden trap is simply at disadvantage now.
The thing people most forget about Darkvision n darkness is applying -5 to Passive Perception.
.. And the fact that you can't see color - only black and white.
I have a group that was moving through the underdark using only Darkvision. This made it very challenging to properly hide their tracks (or see other tracks) because they couldn't see the small details very well since it was all in shades of gray. There was a group of drow following them who WERE using light sources since they realized how much easier it was to track someone that way (and they didn't care about their light sources being seen). Most habitation for creatures with darkvision in my worlds is typically at least dimly lit for the commonly occupied areas since it is so much easier and pleasant to see (and you don't need to worry as much about pesky gloomstalker rangers among others :) ).
In total darkness there is no light to see no matter how sensitive your eyes are, so you see nothing.
Darkvision is just a very unsatisfactory simplification of the old fashion rules on infravision and ultravision which were not great but at least had a modicum of logic to them.
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Hello.
I have recently become aware that we have been using darkvision wrong and want to fix this oversight.
Where in the source material is a breakdown of darkvision, and how it affects PCs in regards to vision, perception, etc(ie dice rolls, combat, etc).
Thank you,
Evan
The rules are described in the PC's race's traits.
e.g for Elves
for Dwarves, it is:
You then need to find the rules about what "dim light" and "bright light" mean. This can be found here, https://www.dndbeyond.com/sources/basic-rules/adventuring#VisionandLight (which also has a generic description of darkvision).
You basically ignore dim light, but in darkness you have disadvantage on perception checks that use vision and can't see color.
That is it. Pretty simple.
Creatures without darkvision have disadvantage on perception checks that rely on sight in dim light, but can still see color, but are blinded in darkness.
The rules for Darkvision are in the Vision and Light rules of Chapter 9 of the PHB and are repeated for each race that has it.
"Darkvision
Many creatures in fantasy gaming worlds, especially those that dwell underground, have darkvision. Within a specified range, a creature with darkvision can see in dim light as if it were bright light and in darkness as if it were dim light, so areas of darkness are only lightly obscured as far as that creature is concerned. However, the creature can’t discern color in that darkness, only shades of gray."
In the same section:
"A given area might be lightly or heavily obscured. In a lightly obscured area, such as dim light, patchy fog, or moderate foliage, creatures have disadvantage on Wisdom (Perception) checks that rely on sight."
Also in the same section:
"Dim light, also called shadows, creates a lightly obscured area. An area of dim light is usually a boundary between a source of bright light, such as a torch, and surrounding darkness. The soft light of twilight and dawn also counts as dim light. A particularly brilliant full moon might bathe the land in dim light."
Combining these: A creature with Darkvision sees darkness as if it was dim light. Dim light is a lightly obscured area. When trying to see something in a lightly obscured area, creatures have disadvantage on perception checks that rely on sight.
These also have interactions with other rules like the Skulker feat:
---
Skulker
Prerequisite: Dexterity 13 or higher
You are expert at slinking through shadows. You gain the following benefits:
---
A creature using darkvision to see in darkness views dim light which is a lightly obscured area. This allows any creature with the Skulker feat to take the hide action even if they can be seen in the darkness because the area is lightly obscured to the creature using darkvision.
Another example could be the Wood Elf feature:
"Mask of the Wild. You can attempt to hide even when you are only lightly obscured by foliage, heavy rain, falling snow, mist, and other natural phenomena."
It depends on whether the DM considers darkness to be a natural phenomena. Personally, I would since darkness is a pretty natural phenomena and so a Wood Elf should be able to take the hide action in a dark area when trying to hide from creatures with darkvision.
The others covered this pretty ok, but it's worth noting that the core vision rules are a mess (some rules are missing, some contradict other rules, and some are just deeply confusing), so covering how darkvision modifies visibility may be insufficient for your needs if whatever is going on with how you've been messing up darkvision is connected to getting visibility itself wrong.
By way of my favorite example: the rulebook unequivocally states that darkness and opaque fog work the same way in-game, but because this is antithetical to how visibility works in the real world, many DMs (including me) house-rule this. It's not terribly useful exploring how darkvision modifies visibility in darkness until you've first committed to an answer on whether or not you actually want your darkness to behave like opaque fog.
I agree the rules for heavily obscured are broken. They really need to treat darkness, fog and foliage differently.
However, as far as darkvision goes - darkvision turns darkness into a lightly obscured area and has no effect on seeing in fog. So dealing with darkvision and darkness (even magical darkness since the spell says that darkvision can't see through it), doesn't really require resolving the issue with heavily obscured areas since those only apply when trying to view them with normal vision or viewing things outside of the range of darkvision. Inside darkvision range, darkness is a shadowy dimly lit region considered to be lightly obscured which prevents the issues with heavily obscured areas from coming up.
Two more examples:
All comes down to what OP intends. Here's how I rule at my table, with annotations where I know at least a substantial minority of DMs disagree with me:
Doesn't this get into the whole question of perception vs reality that someone seems to be arguing about endlessly in another thread?
Perceiving darkness as dim light doesn't change the fact that the creature is still surrounded by darkness. Darkvision lets the creature perceive darkness as dim light. It doesn't change the lighting to dim light. Similarly darkvision allows a creature to perceive dim light as bright light. It doesn't change the external condition to bright light.
From the Elf traits:
"Darkvision. Accustomed to twilit forests and the night sky, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray."
The "as if" is significant since this means it does not change the external lighting (which makes sense) so there is no way it can stack with itself since the external condition is either bright light, dim light or darkness and darkvision only triggers off the actual lighting not how it is perceived. Darkness and dim light are specific game terms that are defined in the vision section of the rules.
I think what you are trying to get at here is the issue with the rules that we have already pointed out as making no sense so I am not sure why bring up an example using it. Most DMs house rule darkness and light to work how we think it should work and not the way the rules are written. As written, darkness by itself is a heavily obscured area so you can't see through it to a lighted region outside the darkness. Of course that makes no sense for most people and as a result most people house rule it.
However, since we already agreed that this makes no sense and that usually DMs house rule it so that a creature IN darkness CAN see a lighted area through the darkness then we can either discuss how the broken RAW would interpret it or how the DM might houserule it but trying to create an example in terms of understanding darkvision isn't effective since the issue has to do with seeing in darkness when a creature does not have darkvision.
In your example, if both creatures have darkvision, there is no issue since they can both see each other no matter what the lighting conditions. If the creature in the light has darkvision and the creature in the darkness does not then RAW the creature in the darkness can't see the creature in the lighted area but the creature in the lighted area with darkvision can see the creature in the darkness. Clearly this doesn't make any sense which is why most DMs run it more consistent with the real world and ignore the rules (which is exactly what a D&D DM should do when there is a rule whose interpretation is ambiguous).
In terms of lightly obscured - do you mean Disadvantage on perception checks relying on sight (you just say Disadvantage so I wasn't sure)? RAW, lightly obscured has no effect on attack rolls.
In terms of what I actually play with, I think I use rules pretty much identical to the ones you do (including treating magical darkness as a heavily obscured area) though I had not considered the case of light fog (though it makes sense), as would light foliage, in terms of causing a lightly obscured area. I also agree with viewing an area through an area of light fog or light foliage would be treated as lightly obscured as well since that also makes sense (whereas viewing an area of light through an area of darkness (whether with darkvision or not) would not be similarly obstructed).
Two massive discussions have already occurred in the last few days about darkvision. Do you really need to start another long lengthy analysis here?
We've answered the OP's question about where to find the actual rules about Darkvision.
Yep, the rules miss the difference between obscurement you can see though (normal darkness) and obscurement you can't see through (fog, foliage). This means that there is no clarity over which type magical darkness is (the "vantablack vs inkblot" discussion).
My attempt to simplify it.
To see an object or person, you only need to consider two factors.
(1) Is there any obscurement between you and the object or person?
Yes: You can't see them.
No: Go to question 2.
(2) What is the level of light where the object or person is?
Bright: You can see them clearly.
Dim: You can see them dimly - you have disadvantage on Wisdom (Perception) checks.
Dark: You can't see them.
If you have darkvision and they are in range of it then the answers to question 2 become:
Bright: You can see them clearly.
Dim: You can see them clearly.
Dark: You can see them dimly - you have disadvantage on Wisdom (Perception) checks and you can't see colours.
Does that look right?
So from what I can tell no one has been using Darkvision incorrectly?
Because if Darkvision is Dim Light and Dim Light is Lightly Obscured and Lightly Obscured is just Disadvantage on Wisdom (Perception) checks only, then what are people getting wrong?
PCs and NPCs can still attack or cast spells as normal but detecting a stealthed enemy or a hidden trap is simply at disadvantage now.
The thing people most forget about Darkvision n darkness is applying -5 to Passive Perception.
.. And the fact that you can't see color - only black and white.
I have a group that was moving through the underdark using only Darkvision. This made it very challenging to properly hide their tracks (or see other tracks) because they couldn't see the small details very well since it was all in shades of gray. There was a group of drow following them who WERE using light sources since they realized how much easier it was to track someone that way (and they didn't care about their light sources being seen). Most habitation for creatures with darkvision in my worlds is typically at least dimly lit for the commonly occupied areas since it is so much easier and pleasant to see (and you don't need to worry as much about pesky gloomstalker rangers among others :) ).
Its all a load of baloney anyway.
In total darkness there is no light to see no matter how sensitive your eyes are, so you see nothing.
Darkvision is just a very unsatisfactory simplification of the old fashion rules on infravision and ultravision which were not great but at least had a modicum of logic to them.