Tactical Visibility and Detection Using Observation

[swaghauler]

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.

[WallShadow]

Originally Posted by swaghauler

I have always found the encounter range rules to be fairly weak in Twilight.
<Snip>
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. 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.
<SNIP>

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.

Me Likee!!!!
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?

[CDAT]

It may just be me, but those ranges look short of what they should be. Years ago when I was still in Tanks, we had to ID vehicles out to 3000+ meters, and spot them further than that.

[swaghauler]

Originally Posted by CDAT

It may just be me, but those ranges look short of what they should be. Years ago when I was still in Tanks, we had to ID vehicles out to 3000+ meters, and spot them further than that.

Using only your eyes or an optic? It seemed "Counter-Intuitive" to me too... until I took a 4-hour course in "Glassing" (observation training for hunting). I'd have to see you spot a man-sized object beyond 1000 meters without an optic. The Army also did several tests and the average adult with 20/20 vision has about a 3% chance to see a man at 1000 meters. AFV's ranged a bit longer based on the size of the vehicle in question. I settled on the "middle ground" of the three tests I read about. If you were using the M1's gunsight, you were using either X3 or X10 magnification in your sighting exercises. This would extend your range of Detection/Identification. Keep in mind that on a flat plane, a man can only see to 5Km due to the curvature of the Earth.
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?

[CDAT]

Originally Posted by swaghauler

Using only your eyes or an optic? It seemed "Counter-Intuitive" to me too... until I took a 4-hour course in "Glassing" (observation training for hunting). I'd have to see you spot a man-sized object beyond 1000 meters without an optic. The Army also did several tests and the average adult with 20/20 vision has about a 3% chance to see a man at 1000 meters. AFV's ranged a bit longer based on the size of the vehicle in question. I settled on the "middle ground" of the three tests I read about. If you were using the M1's gunsight, you were using either X3 or X10 magnification in your sighting exercises. This would extend your range of Detection/Identification. Keep in mind that on a flat plane, a man can only see to 5Km due to the curvature of the Earth.
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?

The man sized I can not say, 1000 meters there sounds about right to me (maybe to far to be honest with any camo). As for vehicles it was a crew effort, driver and Loader normally with no magnification, gunner with the X3 power, and tank commander sometimes with bino's, some times with the Mk. I Eye. If we did not spot them (not ID, but spot) them by about 2500-3000 we were dead, as in they would kill us. We were expected to engage them by that range if not a bit further. Max effective range (ballistic computer stopped working) was 4000 meters, but it was almost imposable to ID them at that range. Now all of this is terrain dependent if there is woods much shorter ranges, but I spent most of my time in Tanks in the desert so not much terrain for an armored vehicle to hide in. One other thing to remember tanks work in platoons and each tank had it sector to search so you are not searching 360 degrees, more like 100-120 (with overlap). When one of the guys with out magnification would see something that did not look right they would call it out and then one of the guys with magnification would take a second look at it. So what I am getting at is I would say that the 2500-3000 meters is the base line for spotting a vehicle in the open.

[PzAz04TotenMaus]

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.

[swaghauler]

Originally Posted by CDAT

The man sized I can not say, 1000 meters there sounds about right to me (maybe to far to be honest with any camo). As for vehicles it was a crew effort, driver and Loader normally with no magnification, gunner with the X3 power, and tank commander sometimes with bino's, some times with the Mk. I Eye. If we did not spot them (not ID, but spot) them by about 2500-3000 we were dead, as in they would kill us. We were expected to engage them by that range if not a bit further. Max effective range (ballistic computer stopped working) was 4000 meters, but it was almost imposable to ID them at that range. Now all of this is terrain dependent if there is woods much shorter ranges, but I spent most of my time in Tanks in the desert so not much terrain for an armored vehicle to hide in. One other thing to remember tanks work in platoons and each tank had it sector to search so you are not searching 360 degrees, more like 100-120 (with overlap). When one of the guys with out magnification would see something that did not look right they would call it out and then one of the guys with magnification would take a second look at it. So what I am getting at is I would say that the 2500-3000 meters is the base line for spotting a vehicle in the open.

I wasn't going to exceed the Twilight imposed maximum range of 3000 meters on the Encounter Ranges Chart but you do make a good argument.
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.

[swaghauler]

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.