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Why does the A.I. see bodies hidden in complete darkness?


chakkman

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Something which bothers me for quite a while now, even more so, as some map makers seem to enjoy implementing guards which patrol the whole map, and then at one point come across my perfectly hidden bodies. Really sucks, if they can't see me in the shadow, why can they see the bodies in the shadow? Please have a look into this, it totally ruins the gameplay for me. :(

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AI can't see bodies if they're in complete shadow (unless there's some kind of bug at work). If they step on them they'll alert though.

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Wasn't there a similar issue reported by you, Springs, where the ai was visible if only the feets were hidden by a little amount of light, or has this been fixed?

 

@abc123: Hide them better :P

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I hid them perfectly, and they didn't step on them. I noticed that the A.I. discovers the body quite a few times now. In most cases, it were spots i hid before, and they couldn't see me. Just play In The North by grayman, and i hid a body in the armory, in a corner in total darkness, and the guard spotted the body from quite a distance. Really, there has to be something wrong. :wacko:

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Just because you can hide somewhere doesn't mean AI won't see a body there. The player uses a sliding scale of detection, where AI can "slightly" notice you but not fully. Bodies are binary; the AI either notices it or doesn't. So there can be cases where you're hidden enough that the AI just says, "Huh?" as he walks past, but if a body was there, he'd see it.

 

I understand this can seem a bit unrealistic at times, and it would be nice if we could use a gradiant system for bodies too, but there's a performance hit if we do that.

 

That said, there were changes to the body detection system shortly before release, so it's also possible there's a problem that went undetected.

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Alright, that would explain the level of detection. Although the visibility meter seems pretty dark in that corner, i would say completely dark. Just tried to reproduce the situation, but unfortunately, the guard patrols seem pretty random on that map. :/ Noone patrolling there now. Anyway, i'll keep my eyes open, if it happens again

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Also AI are surviving a arrow to the face... kind of makes broadheads feel less impactful and arcadey.

This only applies to ai that were alerted before. If you shoot them in the face while they are not alerted, they'll die.

FM's: Builder Roads, Old Habits, Old Habits Rebuild

Mapping and Scripting: Apples and Peaches

Sculptris Models and Tutorials: Obsttortes Models

My wiki articles: Obstipedia

Texture Blending in DR: DR ASE Blend Exporter

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Heh. It's an abstraction, obviously, but it's supposed to represent the fact that they're dodging or flinching at the last second to minimize the damage.

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This is easy to reproduce on NHAT, 2nd mission. There's two builders guarding a sewer if you knock out the one on the step the other ai will see the body and investigate. However if you shoulder the body you can walk right past him.

I always assumed I'd taste like boot leather.

 

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This is easy to reproduce on NHAT, 2nd mission. There's two builders guarding a sewer if you knock out the one on the step the other ai will see the body and investigate. However if you shoulder the body you can walk right past him.

 

Where can I get the released version of NHAT? I tried the in-game downloader, but I can't get a response from our server. I went to the NHAT beta test thread and grabbed a copy using Biker's link in the last note.

 

When I start anoott manually (using the console) I get an error that some bag is missing a collision model.

 

So I'm wondering if I have the latest version.

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Then I'll have to wait for our server to come back.

 

While I'm waiting, I could use some details.

 

Where was the body, and where was the guard seeing the body?

 

There are two street lamps close to those steps. Did any part of the body appear to lie w/in the light from those lamps?

 

I notice that on expert difficulty, the two guards switch from team 2 to team 1. On which difficulty level did you experience the problem?

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The problem is in fact reproducible on Requiem. Here is a savegame. It's still quite at the beginning of the FM, so the savegame won't spoil THAT much, if you haven't played the FM already. This issue seems to be something worth scheduling for 2.01 as it kind of breaks the body-hiding game-mechanic.

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Prelim findings ...

 

In the case of the fallen Builder in Requiem, he has a tall streetlamp nearby. That lamp is throwing enough illumination on the body to make it visible when other AI are less than 291 from it. When one of the patrolling guards gets closer than that, he spots the body.

 

There are at least two bugs in the illumination code, but the main problem is this:

 

The streetlight has an asymmetric light volume, so that the light doesn't travel far horizontally, but does vertically. It appears that the code is assuming a symmetric light volume, and is applying the large vertical distance horizontally, allowing it to fall on the body, which lets the body be seen.

 

This might turn out to be a simple fix, but lights can throw all sorts of falloff patterns, and I need to make sure that fixing one pattern doesn't screw another.

 

So this isn't an "AI can see in the shadows problem", but is a problem caused by nearby odd-shaped light volumes.

 

And this is an old problem, since the code in this area hasn't changed in a long time. (Can't check exactly because the bugtracker is unreachable.)

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I looked at NHAT/2 again and there's a streetlamp near the guard sitting on the steps that has a tall vertical radius compared to its horizontal radii.

 

I'm certain this is the same problem I'm seeing in Requiem: the illumination code is wrongfully concluding that the lamp is shining on the body.

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I might raise a few eyebrows in asking this, but I guess I might as well since it's related to this topic somewhat.

 

Should unconscious or dead guards be hidden by shadow at all?

 

 

I can see a few incentives for not having bodies hidden by shadow:

 

-It would be somewhat consistent with how player weapons affect stealth. The player gets a shadow stealth penalty for having just a sword or a bow out. The guards are often covered in metal, and even when they are not they are not exactly dressed to be hidden in a dark corner.

 

-Also, whether a body is "hidden" or not is a bit of an ambiguous question at times, as bodies don't get light gems. If bodies couldn't "shadow stealth" at all and that is made clear from the get go, then it would be harder in some ways but also easier in others as it would be more straightforward and understandable. There wouldn't be as much of this uncertain "is the body hidden by shadow or not" mess and there would be fewer situations where the player may or not feel cheated.

 

-There's also the fact that some people think the Blackjack is a bit too effective at times, and this would be a nice indirect way to discourage its use that isn't insurmountable. I don't think I've ever run into a situation where I had to Blackjack a guard and at the same time had no way of isolating them from where the other guards patrol.

 

 

Of course, there are more than a few things that would make such a change unpopular (see the thread starting post), but I think the idea is interesting enough to be worth thinking about.

Edited by Professor Paul1290
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Interesting thought there Paul. Although the part about not knowing whether a body is hidden or not is pretty easy though. Find a dark corner and the lightgem will tell you how dark it is. Drop the body there and you will know it's well hidden.

I always assumed I'd taste like boot leather.

 

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