Visibility rules

[Anthony]

Originally Posted by whswhs

You'd need to be significantly closer to recognize facial features, of course.

Yeah, 200-300 was for recognizing facial features. We're actually very sensitive about human-like shapes, you can do a remarkable amount of pixelation before a human (particularly if walking) becomes unrecognizable as human, so as much as a thousand yards is probably plausible.

[condor]

Originally Posted by Anthony

If you want realism, this is the kind of thing the military has studied(I have no links at the moment; haven't looked at this in quite some time).

That was a great hint. Thanks!

http://theantimedia.org/100-military...load-for-free/

In fm90-5 manual (Jungle Operations), page 1-3 it is written that in Tropical Jungle, visibility is less then or equal 55 yards.

https://fas.org/irp/doddir/army/fm90-5.pdf

Annex K of FM 7-93 lists some night operation relevant distances recognition:

http://pdf.textfiles.com/manuals/MIL...tober_1995.pdf
Vehicle headlights - 4 to 8 kilometers
Muzzle flashes from single cannons - 4 to 5 kilometers
Muzzle flashes form small-arms weapons - 1.5 to 2 kilometers
Flashlight - up to 2 kilometers
Bonfire - 6 to 8 kilometers
Lighted match - up to 1.5 kilometers
Lighted cigarette - 0.5 to 0.8 kilometers

The MOUT, Marine on Urban Terrain operations manual, has an interesting table:
http://www.marines.mil/Portals/59/MCWP%203-35.3.pdf

Tank crew members, soldiers (tell them appart from civilians?), antitank gun, antitank missile launchers 500m
Tank APC, truc (by model) 1,000m
Tank, Howitzer, APC, truck 1,500m
Armored vehicle, wheeled vehicle 2000m

Also, I found a very interesting cognitive scientist paper on face recognition. Realistically, facial recognition is something between 25 and a 150 feet, or around 8 to 50 yards:

http://cognitrn.psych.indiana.edu/bu...eyDistance.pdf

https://www.innocenceproject.org/can...-of-feet-away/

I am still searching more daylight info, distances according to the kind of vegetation and variations in contrast (background and object).

[Bruno]

Some of the things that can disrupt facial recognition are interesting. Ignoring brain damage and suchlike, seeing a person out-of-context can prevent recognition.

If you've only ever seen someone in uniform, you'll likely have trouble recognizing them - particularly away from the building they work in, if that's the only place you've seen them. Your brain can get a little lazy and include some of these environmental factors as part of their "face".

Some kinds of face paint or makeup make a person hard to recognize, some don't. And of course things like face scarves, hats, and goggles or sunglasses (common parts of outdoor equipment and of military equipment) can make it pretty darn tricky.

But recognition isn't all about faces - I'm kinda dreadful at facial recognition because of some mild drain bamage (have trouble recognizing my partner and my own mother sometimes :P) but posture, gait, general body language, and of course voice are all helpful. Less reliable but still helpful are haircut, facial hair (if any), glasses, and clothing, and if you can't do the face for whatever reason, general context is enormously helpful (if she's in my mom's apartment and kinda looks like my mom, it's my mom).

[Humabout]

For information on any perception roll, including vision, in a jungle or forest, see The Emerald Hell in Pyramid - Overland Adventures. It covers all aspects of adventuring in jungle environments and includes comments for temperate woodlands, since there is adequate similarities between the two. This includes the effect of undergrowth, trees, weather, lighting, and more on perception checks.