Aeroscout

I could be very wrong here, but this is what I believe is happening. The terrain is actually NOT self shadowing. What's happening is terrain shadows are baked onto the terrain textures for various times of day, and are probably faded from one to the other as time passes. Go ahead and look at a road that passes through the shadow of a hill or mountain, ad you'll notice it's much brighter than it would be (bright as it is in the sun) as it is not affected by the terrain. Same for the cockpit. Fly behind a mountain, and you shouldn't notice anything change regarding cockpit lighting. Personally, I don't think it's a big deal. Whether or not this constitutes false advertisement I'll leave for others to decide. I just wish ED was a bit more upfront about their methods. That said, I think I remember something being mentioned in one of Wag's Sunday videos, but I can't be bothered to find it right now.

It has to do with the trim. I flew the Vegas Tour again today, and once I passed under the bridge, I needed a LOT of nose-up trim. I ended up missing a gate, and while I was circling around, I decided to trim up in level flight, sure enough, I was trimmed back to about 50% longitudinal stick, at a speed where I was normally trimmed at about 10% to 20% (right around the TO trim position). I continued the tour and I ended up passing low and a bit slow over a town when the nose suddenly came up. I re-trimmed nose-down, and the trim position returned to about 20%. So, something funky happens to the aircraft trim when passing under the bridge, almost like there's an additional longitudinal control bias that's added as you pass under, and then removed when you get low and slow enough. Very odd. (For reference, 0% refers to full forward stick, 100% full aft. The TO trim position, where the lines cross in the control display, I'd estimate is around the 20% point.)

Yeah, that's why I was looking for something you could fly through in a fixed wing where this happens. That's an interesting idea. I'll have to give that a shot. The flight model is obviously taking the presence of the building into account, which is interesting. I didn't think it would beyond collision detection. I guess it all comes down to how the flight model is done, and how robust it can be made for these kinds of cases. For instance, the flight model has to know to model ground effect only when above an object, not beneath it. Seems obvious, but is something that could be overlooked. Of course, this issue could have nothing at all to do with ground effect. We have no way of knowing without actually seeing how it's modeled, and from what I know about ED, that's never going to happen.

If a helicopter hovers below a solid surface, it will indeed generate additional lift, and will appear to be sucked up towards it. However, this will only happen within a rotor diameter or two, much like ground effect. Helicopters obviously don't fly under things very often or at all, and so this is never really analyzed. I can't imagine there's much real world data on it. Anyway, that said, I don't think that's what's going on here, and if it is, they've done it wrong. The bridge is way too far in the far field for it to have much effect (remember, we're talking only a rotor diameter or two). Additionally, there's a clear, distinct boundary where the aircraft enters and exits this disturbance. Should it be a real phenomenon, I would think it would fade in and out in some manner.

I decided to take the Huey for a spin under the bridge. Here's how it went: Something's really messed up here, though you say it happens in 1.2/1.5? Is there a bridge in the Black Sea map that exhibits this behavior? I'm wondering if we could give it a try in the A-10C to see if it happens there too.

Just made another video, this time flying the Huey under the bridge several times. Something really strange is happening here, but at this point, I think it's up to the devs to figure it out.

Yup, I noticed this too. First thing I did when I fired up the Nevada map was to fly over the key locations from Fallout New Vegas (I quite like that game). Searchlight (about as far south as you can go before they stopped bothering to detail stuff) should have an airport, but it's only visible as the low res discolorations in the desert you describe. Think I saw one at Primm as well, though google earth suggests otherwise. (On the subject of Primm, ED forgot to add the rollorcoaster there, though I don't think many people are going to be flying to the south end of the map anyway)

I have noticed the issue where there appears to be an impact, but there's in fact no damage. Happens in the video below. So, I did some more flying, and this is what happened. I'll let the video speak for itself. Notice the significantly different trim positions.

I had a look at the landing issue. Something really strange is going on. Notice the significantly different trim positions.

Yup, that's it. It's not really an increase in lift so much as just a disturbance. It happens in yaw, or at least in the inertial XY plane (See the bit where I go under when banked, it seems to be along the horizon). I figured I'd just post the video and be done with it, but now part of me wants to set everything back up and try it with a slower aircraft. That's interesting. I might have to give that a go. Another thing, ground effect isn't going to result in pitch up so much as an overall increase in lift. In a fixed wing aircraft, however, the effect should be very subtle, so I doubt this landing disturbance is ground effect modeling, or at least, it doesn't appear to be proper ground effect modeling if is indeed pitching up.

I don't care about the shadows much, though I'd like to see that fixed as it can be distracting. What I'm referring to is the slight transient (change in flight path and attitude) as the aircraft passes under the bridge. I flew hands off as I passed over and under every time so that everything's clear and obvious that it's not being caused by control inputs. Of course, that made many of my recoveries pretty close-calls. Thanks, glad it's not just me. Because this only happened to me when I enabled wind an turbulence (though I haven't tested either individually) my current theory is ED did some turbulence mapping, increasing turbulence over paved areas. If they made it a function of height, it could explain why the effect is more noticeable under the bridge than over it. I'll have a look at the thread. That was actually my first thought too, but the transient occurs very consistently directly under the bridge.

I get an odd transient/perturbation when flying under the Hoover Dam bridge. Actually, I get it when flying just above it too, but it's more noticeable when going under. The transient only occurs when I added some wind and turbulence. It does not occur when the default weather is used. Honestly, I couldn't be bothered to investigate it any further, so I have only done it in the F-15C and with the Summer Hot with Wind preset. Here's a video showing the transient. Watch closely when passing under and over the bridge. The case where I flew high over the bridge there was no transient, so it appears to be altitude dependent. I know we're not supposed to be flying under bridges, but considering this is a sim, and this is a pretty prominent and easy bridge to fly under, I thought I'd mention it.

I posted the following comment on your video, but maybe others here had similar questions:

The general effect of the water (scaling and shape of the waves) is way off as well, but until we actually have to visually judge sea state for landing on a carrier, I don't think that's as important. It's a good point though.

This is a remnant from the days of lockon 1.0, and t's really hard to understand from a screenshot. See this picture: http://imgur.com/cHoks8E The sea-level water plane is continued to infinity; it is always rendered, even if it's below the terrain. Small rivers are accomplished by laying down a strip with textures and a reflective surface, and for the most part, it works fairly well. This can't be used for larger rivers, however. So, instead, someone thought it would be a good idea to simply rip a hole in the terrain so that you could see the water lying below. It's pretty simple solution, and is fine for a still screenshot, but if you're moving it creates a HORRIBLE parallax effect, especially if you're low, compromising your depth perception. Back in the lockon days, I could accept this. We were flying jets and didn't spend much time down low. However, IMO, as soon as Ka-50 was released, this should have been fixed. I brought this up before somewhere in these forums a long time ago and someone told me I should ignore it because "it's not fishing simulator." It's an example of one of the many reasons I don't frequent the forums or indeed the flight sim community much anymore.