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#1
05-18-2016, 06:45 PM
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Tactical Visibility and Detection Using Observation
I have always found the encounter range rules to be fairly weak in Twilight.
I started doing a little research online and decided after reading TRADOC ARI Technical Report TR-78-A37- Ranges of Detection & Identification of Armored Vehicles, ARI Technical Report TR-753-600 Target Detection & Range Estimation, and the Berkley Study on Range of Facial Recognition; I decided to make some changes in the way Observation is used to Detect and Identify potential encounters. I have listed a rough table for Detection and Identification of vehicle-sized and man-sized objects by "range band" below. I would like the forum's input on the tables and maybe suggestions for improving them before I type them up and laminate them. Please note that I use a different set of Skill Difficulty Levels from the original Twilight2000 2.2 and so I have put my Skill Multipliers in parenthesis after the Skill Difficulty. Version 1 users will actually find the range charts more compatible than version 2.2 users. I have also added a new Very Open Encounter Range (1D10 X 500 meters) to take into account areas of the World where you can see to the horizon (5km). Please note that this table is used AFTER the Encounter Range has been determined as normal, and is simply used to determine the chance of detection by range. Detection Chances of Vehicle Sized Objects By Range: Impossible Level (skill X 0.1) Observation: 3000m to 5000m Formidable Level (skill X 0.25) Observation: 2000m to 3000m Difficult Level (skill X 0.5) Observation: 1500m to 2000m Average Level (skill X 1) Observation: 1000m to 1500m Routine Level (skill X 1.5) Observation: 500m to 1000m Easy Level (skill X 2) Observation: 500m or less Detection Chances of Man Sized Objects By Range: Impossible Level (skill X 0.1) Observation: 700m to 1000m Formidable Level (skill X 0.25) Observation: 500m to 700m Difficult Level (skill X 0.5) Observation: 300m to 500m Average Level (skill X 1) Observation: 200m to 300m Routine Level (skill X 1.5 Observation: 100m to 200m Easy Level (skill X 2) Observation: 100m or less Identification of a Specific Person in a Crowd: Impossible Level (skill X 0.1) Observation: 40m to 50m Formidable Level (skill X 0.25) Observation: 35m to 40m Difficult Level (skill X 0.5) Observation: 30m to 35m Average Level (skill X 1) Observation: 25m to 30m Routine Level (skill X 1.5) Observation: 20m to 25m Easy Level (skill X 2) Observation: 20m or less The overlapping Range Bands are intentional. This is to give the GM the option to change the skill difficulty based on the circumstances of his own adventure/campaign. Please note too, this chart lists only the chance of Detection. Identification of the vehicle or equipment and arms is One Level HARDER. If this results in a chance worse than Impossible, then there is NO CHANCE of Identification. If a Detection Roll is shifted to better than Very Easy (3XSkill), Detection is AUTOMATIC. I shift the difficulty for better or worse depending on various conditions such as movement, visibility of clothing, weather and if the target is partially obscured. Vision Devices: I wasn't very fond of how binoculars are sort of minimized in the game. Optics are a powerful advantage on the battlefield. I decided to follow a derivative of the method I used for scopes. You take the Magnification of the optic and DIVIDE IT BY 2. This Magnification Factor is then used to divide the Encounter Range to determine your Observation Skill roll. For Example, Joe is looking for a hidden APC using a pair of 10X50mm binoculars. Dividing the binocular's magnification in half gives a Magnification Factor of 5. The GM knows the vehicle is 2000 meters away. Dividing 2000 by 5 gives a range of 400 meters. Using binoculars allow's Joe to roll against Easy:Observation instead of Formidable:Observation. I also use Quality levels for my observation devices: Good Quality Optics: provide a bonus of 1 to your roll (so a 15 becomes 14) in addition to the effective range reduction. Standard Quality Optics: provide no bonus but do give the effective range reduction Poor Quality Optics: provide a penalty of 1 to your roll (so a 15 becomes 16) but also allow you to take advantage of the effective range reduction, which makes them better than the naked eye. There's my take on Encounter Detection and Identification. So how do you make the initial encounter more realistic? Swag. Last edited by swaghauler; 05-20-2016 at 04:30 PM. Reason: Rules Changes After Discussions. 
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#2
05-18-2016, 11:34 PM
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 A couple of thoughts glanced across the single neuron flashing bravely in the darkness of my skull: 1. Just to add a quibble or so, would there be a positive multiplier/bonus factor for stabilizing the optics on a tripod or a solid surface? (I have a feeling a bonus of 1 toward the die roll might be more appropriate in this situation). 2. In the opposite direction, would there be a penalty for trying to use optics on an unsteady platform (moving vehicle/animal)? 3. While the optics make things closer, they also tend to exclude light: would there be penalties for dusk/dawn usage?
__________________
"Let's roll." Todd Beamer, aboard United Flight 93 over western Pennsylvania, September 11, 2001.
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#4
05-19-2016, 07:03 PM
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Added Observation Rules As Requested
This system is based on the work I did for Magnified Rifle Optics which you can see in Kdusk's thread "Sniper Shots." There have been a few small modifications to the system, but it is pretty much still as I wrote it up there.
Observation Modifiers: Here are the Observation Modifiers I use in game: 1. Target Moving- One Difficulty Level EASIER 2. Target Wearing Contrasting Clothing (orange or yellow)- One Level EASIER 3. Target is large/long (multi-story building, tractor-trailer viewed from the side)- One Level EASIER 4. Vehicle is "nose on" to Observer, or "hull down"- One Level HARDER 5. Target Camouflaged (matching terrain)- One Level HARDER 6. Light Woods/Rubble/Smoke/Snow- One Level HARDER 7. Heavy Rainfall- One Level HARDER 8. Dense Woods/Rubble/Smoke/Snow- Two Levels HARDER 9. *+OBSERVER Moving- One Level HARDER PER MOVEMENT CLASS (ie. 1 for safe speed, 2 for 2xsafe speed, 3 for 3Xsafe speed). 10. *+OBSERVER Moving Over Rough Terrain- ADD One Level to Movement penalty. *Some optics have "Reflex/Intuitive Focusing" (they automatically focus for you). These Negate 1 LEVEL of movement penalty just like Vehicle Stabilization does. Some optics (or their mounts) are Gyro Stabilized. These Optics negate 2 LEVELS of movement penalty just like Vehicle Stabilization does. + An Observer can reduce movement penalties by rolling under his STR+AGL on 1D20. A success reduces the Movement Penalty by 1 level. Outstanding Success reduces the penalty by 2 levels. These devices and skill rolls CAN ONLY REDUCE MOVEMENT PENALTIES TO 0. You CANNOT GAIN a bonus from using them. Here are the other formulas which are already listed in my "Sniper Shots" post. Light Transmission: This is determined by dividing the Objective of the optic in millimeters by its Magnification to get what is known as the optic's "exit pupil." This exit pupil determines who well the optic performs in low light conditions. If an optic claims to have "95% Light Transmission" in its description, add 1 to its "exit pupil" score. The Exit Pupil is rated according to the following standards: Poor Light Transmission,Exit Pupil 3.9 or less: The optic has less than normal light transmission and low light results in an Increase in Difficulty Level of one. Normal Light Transmission,Exit Pupil 4 to 7: The optic falls into the range of normal human vision. There is no modification to Difficulty Level for the light level (other than what is normally experienced). Good Light Transmission,Exit Pupil 7.1 or Greater: This optic focuses light so well that it is ONE Difficulty EASIER to see with in low light conditions over normal sight. For example, The US Army's newest Tanker binoculars, the Steiner M24 7X50mm Rangefinding Binocular, claims 95%+ light transmission. Using the formula (50/7= 7.14), the exit pupil of these binoculars is 7.14 upgrading to 8.14 for the add of 1. This indicates Good light transmission. Field of View: To determine an optic's field of view, use the following formula- [Field of View in degrees X 52.5]. This will give you the field of view in Feet at 1000 Yards. You then convert this to meters. This measurement is the area a person can search in a single Combat Round (5 seconds) using the optic. Durability: see my post in Kdusk's "Sniper Shots" for an explanation of this. Minimum Observation Range: There IS such a thing as too much magnification. This creates a "confused image" if you look at an object that is too close to you. The Minimum Range of any Optic is its Magnification X 5 in meters. At this range or closer, the Skill Difficulty Level is ONE LEVEL WORSE. At the Optic's Magnification in meters, the Difficulty Level becomes TWO LEVELS WORSE. High Magnification Optics: Above X10 Power in Magnification, it becomes difficult to hold an optic steady enough by hand to see clearly without either a Reflex Focusing System or Gyro Stabilization. There is a penalty of 1 point added to the Observation Roll FOR EACH POINT OF MAGNIFICATION OVER 10. a pair of 25X150mm Marine Binoculars (the kind the Navy uses) will add 15 to your Observation Roll. The only way to negate this penalty is to put the optic on a Bipod/tripod or in a mounting bracket (like the Navy's Bridge mounts). You may use the [STR+AGL] Roll to reduce this penalty as well. The penalty is reduced by 1+ [the difference between roll and target number] on a successful roll. Example: Joe rolls a 7 on a target number of 13. This results in a reduction of 6 off his magnification penalty. This reduction CAN NEVER result in a bonus to Observation. Once again, I would suggest you look at my post in Kdusk's "Sniper Shots" for more info on how I do my optics. Last edited by swaghauler; 05-25-2016 at 01:29 PM. Reason: Changed Rules.
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#5
05-19-2016, 07:15 PM
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I was also surprised to see that most people (about 95%) couldn't identify a person they knew in a crowd past 40 meters (the Berkley Study I referenced). I wonder how many court cases were appealed due to that study?
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#6
05-19-2016, 08:42 PM
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#7
05-20-2016, 11:39 AM
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Would you have a pdf copy of TRADOC ARI Technical Report TR-78-A37- Ranges of Detection & Identification of Armored Vehicles I could grab? I love this sort of stuff.
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#8
05-20-2016, 04:03 PM
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#9
05-20-2016, 04:10 PM
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I guess the best way to do it would be to introduce a new Encounter Range. Very Open Range: this encompasses such terrain as the American Plains, The deserts of Iraq, The African Serengeti and large bodies of open water. Range is 1D10 X 500 meters. This encounter range extends to the horizon. I have made adjustments to my previous rules posts to reflect this new maximum encounter range.
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#10
05-22-2016, 06:44 PM
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Determining Range To A Target
Sometimes it is necessary to know the range to an object or person during play. I use the following rules to determine the range of an object using Stadiametric Rangefinders, Laser Rangefinders, or even the "MK1 Eyeball."
Stadiametric Rangefinders: These rangefinders use either vertical or horizontal lines to determine the range of an object of "Known Size." These rangefinders are "target specific," being designed for either vehicles or people. In the vast majority of Stadiametric Rangefinders, the user either "sandwiches the target" between two horizontal lines or "chokes the target" between two vertical lines to determine the range. A few (especially scopes) will use precisely sized circles, mildots, or "hashmarks"/chevrons for range estimation. When using a Stadiametric Rangefinder, the player determines his Observation Skill roll by using The Chance of Vehicle Detection Chart (even for people). This represents the fact that Stadiametric Rangefinders become progressively more inaccurate as range increases. The following conditions will also impact the character's chance of successfully ranging the object in question: -Using a Stadiametric Rangefinder of the wrong "target type" (ie using a rangefinder configured for a vehicle to range a man and vice versa): 1 Level more Difficult. -Light fog/snow/smoke or heavy rain: 1 Level more Difficult. -Heavy fog/smoke or snow: 2 Levels more Difficult. -Target movement: 1 Level more Difficult per speed level (1 at safe speed, 2 at 2 x safe speed, 3 at 3 x safe speed). Laser Rangefinders: Using a hand-held Laser Rangefinder is an Easy (2xSkill) task of Observation, REGARDLESS OF RANGE, so long as the Laser Rangefinder has the range to reach the target. The effectiveness of Laser Rangefinders can be affected by the following conditions; -Laser Rangefinders are blocked by White Phosphorous OR Dual Spectrum Smoke. They are also blocked by the aerosol from the Shorta Countermeasures system. -Heavy snow or rain can reduce the Skill Roll to Routine (1.5xSkill). -Laser Absorbing Paint will cause a penalty of 1 point to the skill roll (a roll of 14 becomes 15). "Improvised Ranging Devices:" These devices allow you to measure an object of known size with a device that has a known or measurable "reference line." You then put your "Improvised Ranging Device's" reference line over the target you wish to range. Simple Geometry then allows you to determine the range. Examples of "Improvised Ranging Devices" include but are not limited to Lensatic Compasses with sighting systems that have crosshairs, Scopes without rangefinders, Artillery/Mortar Reference Stakes, Plumbobs, and even Sextants used in navigation. Any device with at least a known vertical reference line can be used. The chance of properly ranging a target using this method is the same as trying to IDENTIFY A TARGET off of the Observation Chart (you may substitute Forward Observer/Fire Direction for Observation). You must use the appropriate chart (vehicle-sized or man-sized) as well. All of the conditions that apply for Stadiametric Ranging Apply here with one exception, YOU CANNOT USE THIS METHOD ON A MOVING TARGET. The "MK1 Eyeball" Method of Ranging: It is possible for experienced observers to estimate range right off the top of their head. The Character MUST roll on the appropriate Target Detection Chart and ALL of the Conditions for Stadiametric Ranging apply. The Base Skill chance for this task is TWO LEVELS GREATER THAN THE DETECTION CHANCE IF USING OBSERVATION. Players may use Forward Observer/Fire Direction in lieu of their Observation Skill. Using Forward Observer/Fire Direction is ONLY ONE LEVEL MORE DIFFICULT THAN THE DETECTION CHANCE. Why Range a Target? Ranging a target gives the following bonuses/effects in my game: 1. A bonus of 1 on all Small Arms and Heavy Weapon's To hit rolls (a 15 becomes a 14). IF THE WEAPON IN QUESTION HAS AN OPTIC OR A SIGHT WITH RANGING ADJUSTMENTS ON IT (H&K drum sights, AK ladder sight) 2. Reduces the initial skill difficulty of Indirect Fire (Difficult becomes Average). 3. Gives the EXACT RANGE to a target (otherwise, the target may be 1D10 meters closer (1-5) OR further (6-10) PER RANGE BAND AFTER SHORT RANGE than the players think the target really is. This can drastically affect ambushes and firefights. 4. Allows the character to determine that a target is within the range of a given heavy weapon, IED, or other devices with a limited range during play. WallShadow, I hope these added rules will help you out. As always, use what you will and ignore the rest. Swag. Last edited by swaghauler; 05-25-2016 at 01:59 PM. Reason: Rules additions.
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#11
05-22-2016, 08:40 PM
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BTW, I'm not sure if I missed it but were Ranging stakes (alternately, "when they get abreast of the burned-out Cadillac") mentioned for static defense situation?
__________________
"Let's roll." Todd Beamer, aboard United Flight 93 over western Pennsylvania, September 11, 2001.
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#12
05-25-2016, 01:58 PM
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In a "Static Defense," a good unit will "Pre-Register" every terrain feature within their sector of fire. The Deflection (horizontal location in mills) and Quadrant (vertical location in mills) of every object will be recorded for very accurate fire. EVERY DEFENDER will have access to the EXACT RANGE of every object in their field of fire. There will be "Short Orders" (pre-determined/arranged fire missions) for the artillery in place. It will take only about 5 to 10 seconds to give out a "Short Order," Compared to 30 seconds for a normal fire mission. I allow AT LEAST ONE Difficulty level easier (and sometimes TWO LEVELS easier) for all first round artillery fire because of this (both direct and indirect fire). All heavy weapons and tripod mounted MGs will have the ranging bonuses above. In addition, any terrain feature that provides protection to attackers from the defender's fields of fire (particularly direct fire) is likely to be "booby-trapped" with mines, barbed wire, punji sticks, or even wild animals like poisonous snakes in ditches and pits. When you consider all of the above are just the most basic precautions a defender may take; You can imagine how "tough a nut to crack" a place like Krakow (that makes munitions and land mines) would be.
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#13
08-03-2016, 07:24 PM
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Chances of Detecting a Target By Range And Light Level
Here are my Observation Tables for Range AND Lighting Conditions. Take a look and let me know what you think. Please note that I use a different set of skill modifiers and I will list them for you. My lighting conditions are as follows;
Daylight: Self explanatory. Dusk/Dawn: The period of time DIRECTLY AFTER the sun has set (when the sky is still light but the shadows are deepening) and BEFORE the Sun has risen in the sky (but that sky is still very light). This could also be a very well lit city street, like the main business strip of a large city. Full Moon: The Moon is high and bright in the sky. Also could be a normal Western city street or US small town main street. Half Moon: A half Moon with stars to boot. Could also be a full Moon in overcast conditions. Partial Moon: Either a quarter Moon or an overcast half moon. Could also be a Post-Exchange city street using torch/lamp light. Starlight: Bright stars with a new Moon. Candlelight style interior lighting. Overcast: No visible stars. Could also be starlight through an overhead cover such as woods or a hole in a roof. Here are my tables.... Chance Of Detecting A Man-Sized Object By Range & Light Level: Difficulty Level:..........Daylight:... Dusk/Dawn:... Full Moon:... 1/2 Moon:... Partial:.... Starlight:.... Overcast: Impossible (Skillx0.1): .... 1000m........ 700m............. 500m........... 300m...........200m........ 100m............. 50m Formidable (Skillx0.25): ... 700m ........ 500m ............ 300m .......... 200m ........ 100m ......... 50m ............ 25m Difficult (Skillx0.5): ......... 500m ........ 300m ............ 200m .......... 100m ......... 50m .......... 25m ............ 10m Average (Skill): .............. 300m ........ 200m ............ 100m ........... 50m .......... 25m .......... 10m ............. 5m Routine (Skillx1.5): .......... 200m ....... 100m .............. 50m ........... 25m .......... 10m ........... 5m ............. 2m Easy (Skillx2): ................ 100m ........ 50m ............... 25m ........... 10m ........... 5m ........... 2m .............. 1m Chance Of Detecting A Vehicle By Range & Light Level: Difficulty Level: ...........Daylight: .... Dusk/Dawn: .... Full Moon: .... 1/2 Moon: .... Partial: .... Starlight: .... Overcast: Impossible (Skillx0.1): ..... 5000m ......... 3000m .............. 2000m ........... 1500m ....... 1000m ......... 700m ........... 400m Formidable (Skilx0.25): .... 3000m ......... 2000m .............. 1500m ........... 1000m ........ 700m ........... 400m .......... 200m Difficult (Skillx0.5): .......... 2000m ......... 1500m .............. 1000m ........... 700m ......... 400m ........... 200m .......... 100m Average (Skill): ............... 1500m ......... 1000m ............... 700m ............ 400m ......... 200m ........... 100m ........... 50m Routine (Skillx1.5): ........... 1000m ........ 700m ................. 400m ............ 200m ......... 100m ............ 50m ............ 25m Easy (Skillx2): .................. 700m ......... 400m ................. 200m ............ 100m ........... 50m ............ 25m ............ 10m These are my initial ranges based on light level. Please feel free to comment. As always, use what you will and ignore the rest. Swag. Last edited by swaghauler; 08-03-2016 at 08:17 PM.
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#14
01-22-2017, 10:17 PM
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Integrating Night Vision Into My Observation Charts
I know that the normal method of doing night vision is to just give it a range and you simply cannot see farther than this limit. I'm interested in treating NV Goggles somewhat more transparently. My thought is to give various Generations of NV Goggles "bonus shifts" on the Observation and Spotting Table based on lighting conditions. My idea would be to list the light levels that you can use the NV Goggles in and what improvements in detection they give while worn. Otherwise, how would they affect the player's skills while in use? Here are some stats for the various generations of night vision intensifiers:
Generation I NV (IR Illuminator needed): This the Russian standard until the late 80's (and the T72/T80). Resolution (Lines per mm): 20 to 25 Signal-to-Noise Ration (the higher the better): 8 to 10 Tube Life (hours of operation): 1500 hrs a 75m maximum range of normal visual recognition is commonly listed. I would say that driving, shooting, or operating hand tools would be TWO LEVELS more difficult. Riding a motorcycle, reading and flying are impossible to do. Chances of Detection: Daylight: NO Dusk/Dawn: NO Full Moon: treat as Dusk/Dawn Half Moon: treat as Full Moon Partial Moonlight: treat as Half Moonlight Starlight: treat as Partial Moonlight Overcast: treat as Starlight Generation II NV: This is the Russian standard from the mid 80's until the late 90's. It is also a Police Standard until the late 90's. Resolution (lines per mm): 40 to 45 Signal-to-Noise Ratio (higher is better): 16 to 20 Tube Life (hours of operation): 5,000 hrs A 200m maximum range of normal visual recognition is commonly listed. I would say that driving, shooting, or normal operation of tools is ONE LEVEL more difficult. Riding a motorcycle or reading would be TWO LEVELS more difficult. Flying would be THREE LEVELS more difficult. Chances of Detection: Daylight: NO Dusk/Dawn: NO Full Moon: treat as Dusk/Dawn Half Moon: treat as Full Moon Partial Moonlight: treat as Half Moon Starlight: treat as Partial Moon BUT requires IR illuminator Overcast: treat as Starlight BUT requires IR illuminator Generation II+ NV: These are "reconditioned" GEN II NV Goggles fitted with GEN III tubes but still using the GEN II imager. Pioneered by Russia but commonly used by American Hog hunters in the late 90's. Resolution (lines per mm): 45 to 54 Signal-to-Noise Ratio (higher is better): 16 to 22 Tube Life (hrs of operation): 10,000 hrs A 300m maximum range of normal visual recognition is commonly listed. Driving and shooting are ONE LEVEL more difficult. Flying and reading are TWO LEVELS more difficult. Chances of Detection: Daylight: NO Dusk/Dawn: NO Full Moon: treat as Daylight Half Moon: treat as Dusk/Dawn Partial Moonlight: treat as Full Moon Starlight: treat as Half Moon Overcast: treat as Partial Moon Generation III NV (including 90's Autogated GEN III): The most common form of Western night vision from the late 80's until the mid to late 90's. Russia caught up to the US with GEN III night vision on the T90 in the late 90's. Autogated night vision would be a Western/NATO exclusive during the Twilight War. Resolution (lines per mm): 64 to 72 Signal-to-Noise Ratio (higher is better): 20 to 24 Tube Life (hrs of operation): 10,000 hrs (Autogated is 5,000 hrs) A 350m range of normal vision is often quoted for GEN III NV. Driving, reading, and shooting all suffer a penalty of 1 on the skill roll (a 14 becomes a 15). Flying is ONE LEVEL more difficult due to the lack of depth perception. Chances of Detection: Daylight: NO Dusk/Dawn: NO (GEN III Autogated is YES as Daylight) Full Moon: treat as Daylight Half Moon: treat as Dusk/Dawn Partial Moon: treat as Full Moon Starlight: treat as Half Moon Overcast: treat as Partial Moon Generation III+ NV Autogated: These 21st Century goggles have a few improvements over traditional GEN III goggles. It uses a white on white technology (as opposed to the green hue more commonly seen) for improved contrast as well as REAL visual depth perception (for flying). There are no penalties when using these NV goggles. Resolution (lines per mm): 76+ Signal-to-Noise Ratio (higher is better): 24 to 30 Tube Life (hrs of operation): 10,000 hrs a detection range of 500m is commonly listed for these. As stated above, there are no skill penalties associated with these goggles. Chances of Detection: Daylight: NO Dusk/Dawn: treat as Daylight Full Moon: treat as Daylight Half Moon: treat as Dusk/Dawn Partial Moon: treat as Full Moon Starlight: treat as Half Moon Overcast: treat as Partial Moonlight Generation IV NV: I have no definitive info on the Fusion sights other than they combine thermal and starlight into one device. Let me know if this is a good start to night vision. CDAT, Army Sgt, I know you have more experience here. your opinions would be appreciated.
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