Perception [Spellbound]
Posted: Thu Nov 11, 2021 5:14 am
First, if anyone knows of past relevant threads that deal primarily with perception (or spot / listen) please link them. Often the den seems to fixate on stealth, and very little is said about perception, but I could be missing important contributions made previously.
Perception is sort of the Ur-skill, even in games without any sort of perception related skill, everyone must still contend with what their characters can see or hear. Maybe like fish in water, it can be difficult for us to explain something we're so immersed within.
My initial draft below is rough with obvious missing pieces, but I am looking for feedback from the community. I will be editing the section below to incorporate changes, suggestions, fixes, etc. Some attempts will be made at formatting, but the primary focus will be on the text itself. I hope this topic finds a little more purchase then my stealth thread.
edit: reorganized section, added a little clarifying text.
~~~
Perception
Your bonus to Perception is calculated by adding together your DEX + SPR + MND and dividing the sum by three ( (DEX+SPR+MND) / 3 ).
Everyone is considered trained in perception even if they have no ranks in it. Perception is divided into three groups: Notice, Combat Sense, Social Sense. Notice also includes two sub groups of Search and Deduction. All Perception checks are modified by relevant distance, see Size, Distance modifiers and the Horizon for more information.
The basic perception DC is 3 +size - distance + misc, with those using stealth replacing the 3 with their stealth roll. The one rolling perception wins ties.
Notice
The default perception check, notice determines what pertinent details you pick up in your environment. Notice is also rolled when searching an area, or making a deduction. Typically a failed Notice check cannot be rerolled.
Search
Outside combat, declare the area being searched as well as the type of search being done: quick, careful, thorough, exhaustive. A player can always declare another search of the area but it must be more extensive than the previous search (from quick to careful), but cannot go backwards or redo the same sort of search. Anyone may find traps, secret doors/compartments through searching.
The GM should determine the total time it would take to search the declared area using the following guidelines.
A quick search assumes taking 1 AP per square, an especially dense square (searching through a pile of hay, opening multiple small compartments in a drawer) takes 3 AP per square. The searcher makes a single blind search roll.
A careful search does not require a roll, instead the searcher is assumed to have rolled a ‘10’ plus or minus any relevant modifiers (almost always gaining +1 for being adjacent to the space being searched). A careful search takes 3 AP per square, and especially dense squares takes 9 AP.
A thorough search does not require a roll. Instead the searcher is assumed to have rolled a ‘15’ plus or minus any relevant modifiers (almost always gaining +1 for being adjacent to the space being searched). A thorough search takes 1 minute per square and especially dense squares take 3 minutes.
An exhaustive search does not require a roll. Instead the searcher is assumed to have rolled an ‘18’ plus or minus any relevant modifiers (almost always gaining +1 for being adjacent to the space being searched). An exhaustive search takes 3 minutes per square and especially dense squares take 9 minutes.
During combat, only quick searches can be made. Searches often involve the clearing away of concealment which may reveal anyone using stealth in that square. If you happen to be searching the square someone is hiding in, and they have some other form of concealment, immediately make an additional perception (combat sense) check with a +3 bonus -- this is a one off check only applied to the characters hiding in the square being searched and does not count as the ‘free’ perception (combat sense) check made per round, nor does this result persist between turns as would a normal perception (combat sense) check.
Searching can also be used to find tracks, but following tracks requires a Nature (Survival) check.
Deduction
Used for investigation, deduction infers some greater truth from an assemblage of facts and observations. The GM may call for a deduction if they believe the characters have access to all the pieces of a clue but their players may have forgotten certain details or have not otherwise deduced the import of these clues. A PC may ask for a roll in order to be provided relevant information in a given circumstance, examples could be investigating a crime scene, interviewing witnesses or suspects, trying to gain insight into grand plans of adversaries. Rerolls are not permitted unless a significant new source of information is found, or the character gains a permanent increase in perception (notice).
Combat Sense
Mostly used in combat, Perception (combat sense) is also used for any opposed stealth checks. Ties go to the one rolling perception (combat sense). During your turn you may opt to roll a Perception (combat sense) check without expending any actions unless you have already rolled perception (combat sense) prior in the round. Otherwise, additional perception checks cost 1 AP, however If opponents are undetected, you may not make any additional perception checks unless your character has a clear and convincing motivation to do so. Your last perception check carries through until the beginning of your next turn.
Social Sense
Used to pick up social cues, and broadly a measure of your empathy. Perception (social sense) can be used to intuit a creatures emotional state such as how comfortable someone is in a given situation, whether a person is likely lying or telling the truth, social status, if someone is under any non-evident constraints, distress, compulsions (magical or otherwise). (un)Successful assessments of social affairs also provide (dis)advantage in any relevant Guile checks.
Common Senses and Special Senses
Demi-humans are assumed to have the 5 common senses -- Sight, Hearing, Smell, Touch, and Taste. Some creatures may have additional senses or especially well developed versions of the common 5. For the typical commoner, of the common 5 senses, Sight and Hearing are the dominant senses and often the first ones that are relevant. Stealth requires concealment from sight -- without some special ability, a high stealth roll will not allow someone to hide if they are plainly visible.
A general distinction is made between a sense that is precise or more coarse-grained. Special senses, or regular senses that are heightened, will often be given a ‘sight’ and ‘sense’ range. Bonuses and advantages are generally provided to those making perception checks if such an ability is relevant, and for high precision abilities that are counted as ‘sight’, automatic detection is provided. As an example, many undead have a lifesense and lifesight ability, which functions independently of the common 5 senses to detect anyone considered alive. Those attempting to stealth within an undead's lifesense rolls stealth as usual, but unless they have special abilities,they will be automatically detected if they enter the lifesight range, just as if they were plainly visible to someone's eyesight.
For legacy reasons, ‘hearing-sight’ will be referred to as blindsight, ‘smell-sight’ as scent.
Demi-huamns are considered to have ‘touch-sight’ 0m, that is they automatically detect anything that is touching them. The same goes for taste (they automatically detect anything they taste).
Related conditions:
Blindness. You cannot see. Everyone is considered invisible to you. Without some other special ability, you cannot detect anyone beyond 300m unless they are extremely loud or otherwise. You are considered flat-footed. Anything that reasonably requires sight automatically fails. Any unknown terrain is considered difficult terrain.
These drawbacks are assumed for those who become temporarily blind. Anyone who is permanently blind can overcome some of these constraints, in particular: you are not automatically considered flat-footed (you are still flat-footed to anyone you have not detected), and unknown terrain is not considered difficult terrain.
Size, Distance Modifiers and the Horizon
Distance to the relevant source impacts perception and is done by range categories.
Adjacent, within 1 meter, +1
Close, within 2-10 meters, +0
Medium, 11-30 meters, -1
Long, 31-100 meters, -2
Extreme, 101-300 meters, -3
Overland, 301-1000 meters, -4; 1001m-2000m -5, 2001m-3000m -6, 3001m-4000m -6, 4001m-5000m -7
Assign an additional -1 penalty for every 1000 meters beyond Overland. For large distances, calculate the beginning of the range in 1000s of meters and add an additional -3 penalty -- so something 27000 to 28000 meters away is 27+3, or -30 in total.
Without elevation, a medium sized creature cannot see anything beyond the horizon which is 5000 meters unless the object is 1 meter or taller.
The general equation being used to determine distance to horizon is 3.6*sqrt(height), distance is rounded down to 100s of meters.
Sight distances assume an exceptionally clear day with no other obstructions. Weather conditions can reduce these distances by 10%, 20%, 50% or more.
Light sources are much easier to see, without other obstructions a candle can easily be see from 2500m, and a torch from 3000m
Assume objects larger than colossal can be seen automatically once they appear on the horizon. A basic rule of thumb can be if the object isn’t at least 1/10000th the size as the distance it cannot be seen unless it is also admitting light in which case it’ll appear like a star to most onlookers. (While these guidelines are intended for extremely large objects, applying this to a 2m sized creature, it assumes it cannot be seen if further than 20,000m; within the rules of the system this would otherwise be a DC 3 + size0 -distance(-22) = DC 25.)
Height Horizon
1m 3600m
2m 5000m
3m 6200m
4m 7200m
5m 8,000m
6m 8,800m
7m 9,500m
8m 10,100m
9m 10,800m
10m 11,300m
12m 12,400m
14m 13,400m
16m 14,400m
18m 15,200m
20m 16,000m
25m 18,000m
30m 19,700m
35m 21,200m
40m 22,700m
45m 24,100m
50m 25,400m
60m 27,800m
70m 30,100m
80m 32,100m
90m 34,100m
100m 36,000m
150m 44,000m
200m 50,900m
250m 56,900m
300m 62,300m
400m 72,000m
500m 80,400m
1000m 113,800m
2000m 160,900m
3000m 197,100m
4000m 227,600m
5000m 254,500m
10000m 360,000m
Calculating the distance two tall objects can see each other is 3.6*sqrt(h1+h2) *1000m, distances rounded down as above. see table below for reference
Creature sizes
For weight, creatures will typically range 1kg to 150kg per cbm.
Creatures can be of different dimensions but should adhere to their cubic meter (cbm) range; here width and length are assumed to be the same. Size is an approximation of the space a creature comfortably occupies, and isn’t assumed to fill the entire space.
Scaling down
For weight, creatures will typically range 0.001mg to 0.15mg per mm^3.
Creatures not using stealth are assumed to be defaulting to a 3 before adding any relevant modifiers. For example, for a medium sized commoner to see an unarmored Storm Giant (10m height) walking over a clear plain at the maximum horizon distance (11,300m), would require a DC 3 - 4size +14(distance) or DC 13
Perception is sort of the Ur-skill, even in games without any sort of perception related skill, everyone must still contend with what their characters can see or hear. Maybe like fish in water, it can be difficult for us to explain something we're so immersed within.
My initial draft below is rough with obvious missing pieces, but I am looking for feedback from the community. I will be editing the section below to incorporate changes, suggestions, fixes, etc. Some attempts will be made at formatting, but the primary focus will be on the text itself. I hope this topic finds a little more purchase then my stealth thread.
edit: reorganized section, added a little clarifying text.
~~~
Perception
Your bonus to Perception is calculated by adding together your DEX + SPR + MND and dividing the sum by three ( (DEX+SPR+MND) / 3 ).
Everyone is considered trained in perception even if they have no ranks in it. Perception is divided into three groups: Notice, Combat Sense, Social Sense. Notice also includes two sub groups of Search and Deduction. All Perception checks are modified by relevant distance, see Size, Distance modifiers and the Horizon for more information.
The basic perception DC is 3 +size - distance + misc, with those using stealth replacing the 3 with their stealth roll. The one rolling perception wins ties.
Notice
The default perception check, notice determines what pertinent details you pick up in your environment. Notice is also rolled when searching an area, or making a deduction. Typically a failed Notice check cannot be rerolled.
Search
Outside combat, declare the area being searched as well as the type of search being done: quick, careful, thorough, exhaustive. A player can always declare another search of the area but it must be more extensive than the previous search (from quick to careful), but cannot go backwards or redo the same sort of search. Anyone may find traps, secret doors/compartments through searching.
The GM should determine the total time it would take to search the declared area using the following guidelines.
A quick search assumes taking 1 AP per square, an especially dense square (searching through a pile of hay, opening multiple small compartments in a drawer) takes 3 AP per square. The searcher makes a single blind search roll.
A careful search does not require a roll, instead the searcher is assumed to have rolled a ‘10’ plus or minus any relevant modifiers (almost always gaining +1 for being adjacent to the space being searched). A careful search takes 3 AP per square, and especially dense squares takes 9 AP.
A thorough search does not require a roll. Instead the searcher is assumed to have rolled a ‘15’ plus or minus any relevant modifiers (almost always gaining +1 for being adjacent to the space being searched). A thorough search takes 1 minute per square and especially dense squares take 3 minutes.
An exhaustive search does not require a roll. Instead the searcher is assumed to have rolled an ‘18’ plus or minus any relevant modifiers (almost always gaining +1 for being adjacent to the space being searched). An exhaustive search takes 3 minutes per square and especially dense squares take 9 minutes.
During combat, only quick searches can be made. Searches often involve the clearing away of concealment which may reveal anyone using stealth in that square. If you happen to be searching the square someone is hiding in, and they have some other form of concealment, immediately make an additional perception (combat sense) check with a +3 bonus -- this is a one off check only applied to the characters hiding in the square being searched and does not count as the ‘free’ perception (combat sense) check made per round, nor does this result persist between turns as would a normal perception (combat sense) check.
Searching can also be used to find tracks, but following tracks requires a Nature (Survival) check.
Deduction
Used for investigation, deduction infers some greater truth from an assemblage of facts and observations. The GM may call for a deduction if they believe the characters have access to all the pieces of a clue but their players may have forgotten certain details or have not otherwise deduced the import of these clues. A PC may ask for a roll in order to be provided relevant information in a given circumstance, examples could be investigating a crime scene, interviewing witnesses or suspects, trying to gain insight into grand plans of adversaries. Rerolls are not permitted unless a significant new source of information is found, or the character gains a permanent increase in perception (notice).
Combat Sense
Mostly used in combat, Perception (combat sense) is also used for any opposed stealth checks. Ties go to the one rolling perception (combat sense). During your turn you may opt to roll a Perception (combat sense) check without expending any actions unless you have already rolled perception (combat sense) prior in the round. Otherwise, additional perception checks cost 1 AP, however If opponents are undetected, you may not make any additional perception checks unless your character has a clear and convincing motivation to do so. Your last perception check carries through until the beginning of your next turn.
Social Sense
Used to pick up social cues, and broadly a measure of your empathy. Perception (social sense) can be used to intuit a creatures emotional state such as how comfortable someone is in a given situation, whether a person is likely lying or telling the truth, social status, if someone is under any non-evident constraints, distress, compulsions (magical or otherwise). (un)Successful assessments of social affairs also provide (dis)advantage in any relevant Guile checks.
Common Senses and Special Senses
Demi-humans are assumed to have the 5 common senses -- Sight, Hearing, Smell, Touch, and Taste. Some creatures may have additional senses or especially well developed versions of the common 5. For the typical commoner, of the common 5 senses, Sight and Hearing are the dominant senses and often the first ones that are relevant. Stealth requires concealment from sight -- without some special ability, a high stealth roll will not allow someone to hide if they are plainly visible.
A general distinction is made between a sense that is precise or more coarse-grained. Special senses, or regular senses that are heightened, will often be given a ‘sight’ and ‘sense’ range. Bonuses and advantages are generally provided to those making perception checks if such an ability is relevant, and for high precision abilities that are counted as ‘sight’, automatic detection is provided. As an example, many undead have a lifesense and lifesight ability, which functions independently of the common 5 senses to detect anyone considered alive. Those attempting to stealth within an undead's lifesense rolls stealth as usual, but unless they have special abilities,they will be automatically detected if they enter the lifesight range, just as if they were plainly visible to someone's eyesight.
For legacy reasons, ‘hearing-sight’ will be referred to as blindsight, ‘smell-sight’ as scent.
Demi-huamns are considered to have ‘touch-sight’ 0m, that is they automatically detect anything that is touching them. The same goes for taste (they automatically detect anything they taste).
Related conditions:
Blindness. You cannot see. Everyone is considered invisible to you. Without some other special ability, you cannot detect anyone beyond 300m unless they are extremely loud or otherwise. You are considered flat-footed. Anything that reasonably requires sight automatically fails. Any unknown terrain is considered difficult terrain.
These drawbacks are assumed for those who become temporarily blind. Anyone who is permanently blind can overcome some of these constraints, in particular: you are not automatically considered flat-footed (you are still flat-footed to anyone you have not detected), and unknown terrain is not considered difficult terrain.
Size, Distance Modifiers and the Horizon
Distance to the relevant source impacts perception and is done by range categories.
Adjacent, within 1 meter, +1
Close, within 2-10 meters, +0
Medium, 11-30 meters, -1
Long, 31-100 meters, -2
Extreme, 101-300 meters, -3
Overland, 301-1000 meters, -4; 1001m-2000m -5, 2001m-3000m -6, 3001m-4000m -6, 4001m-5000m -7
Assign an additional -1 penalty for every 1000 meters beyond Overland. For large distances, calculate the beginning of the range in 1000s of meters and add an additional -3 penalty -- so something 27000 to 28000 meters away is 27+3, or -30 in total.
Without elevation, a medium sized creature cannot see anything beyond the horizon which is 5000 meters unless the object is 1 meter or taller.
The general equation being used to determine distance to horizon is 3.6*sqrt(height), distance is rounded down to 100s of meters.
Sight distances assume an exceptionally clear day with no other obstructions. Weather conditions can reduce these distances by 10%, 20%, 50% or more.
Light sources are much easier to see, without other obstructions a candle can easily be see from 2500m, and a torch from 3000m
Assume objects larger than colossal can be seen automatically once they appear on the horizon. A basic rule of thumb can be if the object isn’t at least 1/10000th the size as the distance it cannot be seen unless it is also admitting light in which case it’ll appear like a star to most onlookers. (While these guidelines are intended for extremely large objects, applying this to a 2m sized creature, it assumes it cannot be seen if further than 20,000m; within the rules of the system this would otherwise be a DC 3 + size0 -distance(-22) = DC 25.)
Height Horizon
1m 3600m
2m 5000m
3m 6200m
4m 7200m
5m 8,000m
6m 8,800m
7m 9,500m
8m 10,100m
9m 10,800m
10m 11,300m
12m 12,400m
14m 13,400m
16m 14,400m
18m 15,200m
20m 16,000m
25m 18,000m
30m 19,700m
35m 21,200m
40m 22,700m
45m 24,100m
50m 25,400m
60m 27,800m
70m 30,100m
80m 32,100m
90m 34,100m
100m 36,000m
150m 44,000m
200m 50,900m
250m 56,900m
300m 62,300m
400m 72,000m
500m 80,400m
1000m 113,800m
2000m 160,900m
3000m 197,100m
4000m 227,600m
5000m 254,500m
10000m 360,000m
Calculating the distance two tall objects can see each other is 3.6*sqrt(h1+h2) *1000m, distances rounded down as above. see table below for reference
Creature sizes
For weight, creatures will typically range 1kg to 150kg per cbm.
Creatures can be of different dimensions but should adhere to their cubic meter (cbm) range; here width and length are assumed to be the same. Size is an approximation of the space a creature comfortably occupies, and isn’t assumed to fill the entire space.
Scaling down
For weight, creatures will typically range 0.001mg to 0.15mg per mm^3.
Creatures not using stealth are assumed to be defaulting to a 3 before adding any relevant modifiers. For example, for a medium sized commoner to see an unarmored Storm Giant (10m height) walking over a clear plain at the maximum horizon distance (11,300m), would require a DC 3 - 4size +14(distance) or DC 13