Blindsight and blindsence on objects

[alex1g]

Does blindsight/blindsense work on objects?

[liquidformat]

yes unless the monster entry says otherwise, read through Blind Sight and Blindsense (http://www.d20srd.org/srd/specialAbilities.htm#blindsightAndBlindsense)

[Particle_Man]

Tremorsense would usually not work on objects, because objects usually don’t move.

[liquidformat]

Tremorsense would usually not work on objects, because objects usually don’t move.

Neither RAW nor common sense agrees with you on this one. Please Refer to Tremorsense (https://www.d20srd.org/srd/specialAbilities.htm#tremorsense) anything touching the the surface you are using tremorsense on it will show up.

If tremor sense couldn't detect objects then moles would just be running into walls and random stuff all the time.

[Particle_Man]

Neither RAW nor common sense agrees with you on this one. Please Refer to Tremorsense (https://www.d20srd.org/srd/specialAbilities.htm#tremorsense) anything touching the the surface you are using tremorsense on it will show up.

If tremor sense couldn't detect objects then moles would just be running into walls and random stuff all the time.

So creatures have to move to be detected but objects don’t? A paralyzed creature cannot be detected but the life size statue next to them can? Where is the tremor to be sensed if there is no movement?

And what are the second and third paragraphs the tremorsense ability’s description, about creature movement, going on about if movement is irrelevant to being detected?

You didn’t just read the first sentence under the tremorsense description and stop reading, did you?

Don’t know about real life moles but possibly what they use is different from RAW tremorsense.

[Psyren]

So creatures have to move to be detected but objects don’t? A paralyzed creature cannot be detected but the life size statue next to them can? Where is the tremor to be sensed if there is no movement?

And what are the second and third paragraphs the tremorsense ability’s description, about creature movement, going on about if movement is irrelevant to being detected?

You didn’t just read the first sentence under the tremorsense description and stop reading, did you?

Don’t know about real life moles but possibly what they use is different from RAW tremorsense.

Technically it says creatures must be moving to show up. Objects are not creatures, so the first sentence is the only one that applies to them.

[liquidformat]

So creatures have to move to be detected but objects don’t? A paralyzed creature cannot be detected but the life size statue next to them can? Where is the tremor to be sensed if there is no movement?

And what are the second and third paragraphs the tremorsense ability’s description, about creature movement, going on about if movement is irrelevant to being detected?

You didn’t just read the first sentence under the tremorsense description and stop reading, did you?

Don’t know about real life moles but possibly what they use is different from RAW tremorsense.

I have always thought of it anything touching the ground shows up, but that is all, using tremorsense only you have no clue if the thing you are detecting is alive or not only that it is there. It does make sense a creature that can detect tremors can reasonably do it actively or passively, actively is letting to see what impediments are in your way of movement, passive is letting you detect the movements of other things there by identifying them as alive.

On the other hand objects that aren't touching the ground like say a chandelier you don't notice, objects on top of objects touching the ground would probably be at most identified as part of the object touching the ground not its own object.

[Crake]

I have always thought of it anything touching the ground shows up, but that is all, using tremorsense only you have no clue if the thing you are detecting is alive or not only that it is there. It does make sense a creature that can detect tremors can reasonably do it actively or passively, actively is letting to see what impediments are in your way of movement, passive is letting you detect the movements of other things there by identifying them as alive.

On the other hand objects that aren't touching the ground like say a chandelier you don't notice, objects on top of objects touching the ground would probably be at most identified as part of the object touching the ground not its own object.

Yeah, im gonna have to side with Particle_Man on this one. It's called tremorsense. You're sensing tremors. Nonmoving objects don't make tremors, however, if you had some kind of moving machine, like a steam engine or the like, then you would be able to sense that.

[Psyren]

I guess it's a moot point - I'm not aware of any monsters that only have tremorsense, and don't also have sight or blindsense/blindsight.

[Crake]

I guess it's a moot point - I'm not aware of any monsters that only have tremorsense, and don't also have sight or blindsense/blindsight.

Well, considering tremorsense ignores line of effect, there are plenty of times when it could matter, like, y'know, standing behind a wall.

[Psyren]

Well, considering tremorsense ignores line of effect, there are plenty of times when it could matter, like, y'know, standing behind a wall.

Right but how often does a monster need to find an object behind a wall though?
And blindsight/blindsense might also ignore line of effect depending on the sense involved.

[ShurikVch]

I guess it's a moot point - I'm not aware of any monsters that only have tremorsense, and don't also have sight or blindsense/blindsight.
Unseelie Fey template:



91-95
The creature lacks eyes but has tremorsense 30 ft.

[Crake]

Right but how often does a monster need to find an object behind a wall though?
And blindsight/blindsense might also ignore line of effect depending on the sense involved.

Well, perhaps not a wall, but lots of monsters with tremorsense also have a burrow speed, and thus find their prey from underground where they can't see anything.

[Darg]

Neither RAW nor common sense agrees with you on this one. Please Refer to Tremorsense (https://www.d20srd.org/srd/specialAbilities.htm#tremorsense) anything touching the the surface you are using tremorsense on it will show up.

If tremor sense couldn't detect objects then moles would just be running into walls and random stuff all the time.

Not to mention moving at half speed because they can't see and are therefore blind.


Yeah, im gonna have to side with Particle_Man on this one. It's called tremorsense. You're sensing tremors. Nonmoving objects don't make tremors, however, if you had some kind of moving machine, like a steam engine or the like, then you would be able to sense that.

Why can't it be a form of echolocation through a different medium? Unlike Blindsense, it isn't specifically called out that you retain blindness. So one would assume that you can see where you are going while burrowing. This means one would know if they are about to enter an underground cavity and prevent themselves from falling to their death.

[Particle_Man]

Bats have echolocation in real life and this is called blind sense in the game.

Real life moles have the ability to hear vibrations (like predators trying to dig for them) and an awesome sense of touch (allowing them to quickly eat their own prey).

Not running into man made objects is probably not something miles have evolved to counter yet. And I don’t think they burrow fast enough to give them a concussion if their digging leads to a wall or something. They would just have to turn.

[Psyren]

Well, perhaps not a wall, but lots of monsters with tremorsense also have a burrow speed, and thus find their prey from underground where they can't see anything.

I'm not talking about prey though - prey are creatures, and how tremorsense works with creatures is very clear. The question is what do they know about their surroundings if tremorsense is the only sense available.

The examples provided, e.g. eyeless unseelie fey, I don't think are intended to be just running into walls or tripping over loose objects over and over. And as for RAW, the first sentence in tremorsense appears to be the only one that applies to motionless objects.

[Darg]

Bats have echolocation in real life and this is called blind sense in the game.

And yet it is the description of blindsight that has echolocation in it. The difference between blindsight and blindsense is only in the degree of accuracy of the ability.

[Particle_Man]

And neither blindsight nor blind sense are tremorsense. So if you can detect things that are not moving (hence not making tremors) you need blind sense, blind sight, or real sight, or something that is not tremor sense. Luckily 3.5 has these abilities.

If you want to detect something with tremorsense, it needs to make tremors to be sensed. Hence some kind of movement, even if that is casting a spell with somatic components while remaining in place, or being a working multipart steam engine that remains in place I guess.

[Darg]

And neither blindsight nor blind sense are tremorsense. So if you can detect things that are not moving (hence not making tremors) you need blind sense, blind sight, or real sight, or something that is not tremor sense. Luckily 3.5 has these abilities.

If you want to detect something with tremorsense, it needs to make tremors to be sensed. Hence some kind of movement, even if that is casting a spell with somatic components while remaining in place, or being a working multipart steam engine that remains in place I guess.

That's not true. Blindsight and blindsense requires line of effect. While burrowing you wouldn't have that. Meaning you are considered blind, unless tremorsense allows you to see where you are going. If as you say that tremorsense only allows knowing the location of moving creatures and objects, then burrowing creatures can't orient themselves while always traveling at half speed. As I mentioned earlier, this leads to very dire consequences because they cannot know what (or lack there of) is in front of them (like a 200ft pit that is only 2 squares wide, but the creature is in range so they fall into the pit because they can't see where they are going.)

There is also discrepancy between the monster manuals and the DMG.


Tremorsense (Ex): A creature with tremorsense is sensitive to vibrations in the ground and can automatically pinpoint the location of anything that is in contact with the ground. Aquatic creatures with tremorsense can also sense the location of creatures moving through water. The ability’s range is specified in the creature’s descriptive text.

The version describing movement is the DMG. It is quite possible that the intent is the ability to pinpoint anything, but cannot detect if they are creatures unless they move. There is a difference between knowing the location of something and knowing what that is.

[ShurikVch]

That's not true. Blindsight and blindsense requires line of effect. While burrowing you wouldn't have that. Meaning you are considered blind, unless tremorsense allows you to see where you are going. If as you say that tremorsense only allows knowing the location of moving creatures and objects, then burrowing creatures can't orient themselves while always traveling at half speed. As I mentioned earlier, this leads to very dire consequences because they cannot know what (or lack there of) is in front of them (like a 200ft pit that is only 2 squares wide, but the creature is in range so they fall into the pit because they can't see where they are going.)
This never was a problem for earth gliding Earth Elementals (https://www.d20srd.org/srd/monsters/elemental.htm#earthElemental)...

[Particle_Man]

They won’t fall into a pit because they will stop burrowing. They can burrow blind because they can stop if there is a wall or a pit and then go around it. Or over it. Or under it. That is what I imagine actual burrowing creatures do. I don’t think they have magical powers. Are you saying that tremorsense should be treated like darkvision, the strange ability to see in complete darkness (albeit in black and white), usually up to exactly 60’?

[Squire Doodad]

Well, it doesn't work on coins, because then it'd be blindpence! :smallbiggrin:

[Darg]

They won’t fall into a pit because they will stop burrowing. They can burrow blind because they can stop if there is a wall or a pit and then go around it. Or over it. Or under it. That is what I imagine actual burrowing creatures do. I don’t think they have magical powers. Are you saying that tremorsense should be treated like darkvision, the strange ability to see in complete darkness (albeit in black and white), usually up to exactly 60’?

I blind person knows not to fall off a cliff because then they wouldn't be walking anymore? What you are describing is blindly feeling your way. Sounds more like a search check. IRL, burrowing critters don't have tremorsense anymore than a human does. They may feel tremors and learn to understand a general perception towards it, but that wouldn't be any different than an experienced miner understanding what tremors are dangerous and what are simply settling earth. Moles rely on blind digging and an extremely strong sense of smell to find food they come across. Tremorsense on the other hand is much more fantastical in nature, working as a sort of sonar that can bend around empty space for accurate perception of location.


This never was a problem for earth gliding Earth Elementals (https://www.d20srd.org/srd/monsters/elemental.htm#earthElemental)...

Earthglide mentions "as easily as a fish swims through water." I would assume it would also have all the perks a fish has in water like knowing what is around them that aren't hiding or moving too fast to notice. It's not burrowing.

[Particle_Man]

Ok if you think it is explicitly magical “do anything” ability and I don’t then we are going to disagree. I assume your version would be great for miners. I will stick to requiring tremors (ie. movement of some kind) for tremorsense to work. If that is wrong, then I don’t want to be right. :smallbiggrin:

[Darg]

Ok if you think it is explicitly magical “do anything” ability and I don’t then we are going to disagree. I assume your version would be great for miners. I will stick to requiring tremors (ie. movement of some kind) for tremorsense to work. If that is wrong, then I don’t want to be right. :smallbiggrin:

An extraordinary ability does not have to follow the laws of physics; hence the ability to pinpoint a target on the other side of open air as long as the distance through the ground to the target is equal to or less than the range. I just don't think tremorsense is supposed to be as weak as the motion detection only version makes it. I already pointed out the mechanical consequences for it.

And it's not a "do anything" ability. The ability doesn't give you any knowledge of what you are sensing. So you can't tell between a chair or an unconscious person. You only know something is there. If it moves, it's likely a creature so the assumption that it is one would be right 99 times out of 100.

[Particle_Man]

But then tremorsense is too close to blindsense. There is not much point in differentiating the two if tremorsense covers so much of the same, ah, ground.

[Darg]

But then tremorsense is too close to blindsense. There is not much point in differentiating the two if tremorsense covers so much of the same, ah, ground.

Blindsense requires line of effect. Tremorsense does not. Tremorsense also bypasses concealment. Blindsense does not. It also doesn't tread on blindsight either because it also requires line of effect and can work against things not directly touching the ground such as in second story room or a room above a basement. Floor =/= ground.

[Particle_Man]

So your interpretation makes tremorsense better than blind sense? Interesting. I will stick with my interpretation.