[Legbreaker]

Originally Posted by ArmySGT.

I don’t know this rule set.

The following is from 2.0

TACTICAL VISIBILITY
Normal daylight visibility is effectively unlimited, restricted only by intervening terrain and the curvature of the earth. (For a person of normal height standing on a flat plain, the horizon is about five kilometres distant.)
Smoke, adverse weather, and night reduce visibility severely. Dense smoke blocks visibility completely. Light smoke obscures characters and vehicles in and beyond it. In poor weather (light fog, drizzle, and light snowfall), maximum visibility distance is 2000 metres for moving vehicles, and very large objects and structures (such as villages, woods, etc.). For stationary vehicles, small structures (such as bunkers), and moving people, the maximum spotting distance is 1000 meters. For stationary people, it is 500 meters. In bad weather (dense fog, rain, and heavy snowfall), these distances are quartered.
Visibility at night varies considerably, depending on the amount of background light. The referee should assign a background light level of from one to five, with one representing a cloud covered, moonless night (in other words, pitch black) and five a clear night with a full moon high in the sky. Visibility for large structures and moving vehicles is 400 meters times the background light level. Visibility for small structures, stationary vehicles, and moving people is 200 meters times the background light level. Visibility for stationary people is 100 meters times the background light level. Halve the distance for poor weather at night; quarter the distance for bad weather at night.
Encounter Ranges: In poor weather halve all encounter ranges (except in woods). In bad weather, quarter all encounter ranges (except in woods). At night, multiply all encounter ranges (except in woods) by background light level and divide by 10, then modify for poor or bad weather. (Woods are unaffected by reduced visibility, as visibility is already so limited that encounter range depends as much on hearing the encounter seeing it anyway.)
Vision Enhancement Devices: A number of vision enhancement devices are available. They have the following effects.
Binoculars: Binoculars are useful only during periods of good visibility (daylight and good weather). A character who is equipped with binoculars and is in a good observation position (building roof, treetop, hill) has his Observation skill increased by one. If he spots a group before they spot him or the rest of his party, double the range of the encounter.
Starlight Scope: A player using a starlight scope can see twice as far at night as he could without the scope. In an encounter situation, this would allow characters with starlight scopes to begin rolling for spotting before hostile groups would be able to attempt to spot them. Starlight scopes have no effect in woods, smoke, or poor or bad weather.
Image Intensifier: An image intensifier has same effect as binoculars, except that the character adds two to his Observation skill. The device incorporates both telescopic and low-light intensification, and has a maximum range of 900 meters. Image intensifiers have no effect in woods, smoke, or poor or bad weather.
IR Goggles: Infrared goggles allow a character to see moving or stationary personnel or other heat sources at a distance of 300 meters at night. In addition, a character wearing infrared goggles can see the beam of an IR spotlight. IR goggles have no effect in woods, smoke or poor or bad weather.
IR Spotlight: An infrared spotlight can illuminate an area 20 meters across at a range of up to 1000 meters. Only characters wearing IR goggles can see the light.
However, any character wearing IR goggles will see the searchlight if he is within 3000 meters of it. IR spotlights have no effect in woods, smoke, or poor or bad weather.
White Light Spotlight: A white light spotlight will illuminate an area 20 meters across at ranges up to 2000 meters. The light itself can be seen by any character at any distance who has a clear line of sight to it. White light spotlights have no effect in woods, smoke, or poor or bad weather.
Thermal Sight: A thermal sight is a very advanced form of infrared imaging. It allows characters to see vehicles out to 3000 meters and people out to 2000 meters through darkness, smoke, and fog. This range is halved in drizzle and rain, and the device has no effect in snowfall and woods.
Illumination Rounds: An ILLUM round will illuminate the area within its burst radius as if it were full daylight. ILLUM rounds have no effect in woods, smoke, or poor or bad weather.

2.2 is almost identical.