perception of speed is not good

[dali]

hi,

 

there is something strange here. I did a quick test - I was flying with 1000 km/h over runway 3700 m long. It should take me at least 13 seconds to fly from one end to the other. It took me 7-8 but the sensation of the speed was at least two times too slow. Mind you, I was flying military jets in my life and I'm aware that human eye and camera are not comparable in this regard.

 

This is video of the aircraft I used to fly...

The speed at the beginning of the ruwnay is 450-500 km/h (I forgot to ask my brother, who is in this shot about the exact speed), the runway is 3300 m long. Note how quickly the ground is moving relative to the aircraft (note also that the camera is facing backwards, making the effect more dramatic). The GOPRO camera has different viewing angle, because of which the angular speed looks a bit more dramatic, but even when everything is taken into account the perception of the moving terrain is about right, making the perception of the speed in DCS 2.5 wrong. I don't know if this is the limiation of the graphical engine, or something else. But this is the DCS problem from Flanker 1.0 days onward.....

 

I have no idea if this is due to rendering techniques, or scaling of the objects or something third. What I know from my flying experience (low level at speeds 500 km/h plus) is that ground does move fast beneith your plane and the dramatics is of course increasing with lowering the altitude. When flying low in DCS I have the perception of flying from much higher alititude even when flying extremely low. As if the rendering engine (camera) is rendering (regardless if the actual actual proximity to the ground is less than that) some 100 m or more above the GND upwards...

 

I would like ED to prove me wrong.... ;)

 

 

 

jump to

for low level

 

speed over runway in thex shot is 450 km/h and the camera is facing foward. As you can see, the effect of moving ground is less emphesised, but is much more dramatic as in DCS (taking into account the speed!)

 

Edited February 6, 2018 by dali

[=Pedro=]

It's all about FOV. Setting this to something like 90 -100 FOV gives you a great feeling of speed but the screen starts to look like fish-eye-lens effect.

[dali]

@bbrz, please do, I would like to be wrong in this case

[wedge_one]

I was going to post the same thing Pedro did. It's all about fov for perception of speed. Increase your fov and you'll notice the difference, just like in the videos.

[dali]

I know that FOV increases the perception, but FOV is, as I see it in DCS, just a zoom in/out. So it mimics the camera FOV, not the eye. Its just a discussion from my side, I hope it is not perceived as trolling or something.

 

[Oban]

I was flying with 1000 km/h over runway 3700 m long. It should take me at least 13 seconds to fly from one end to the other.

 

I think your calculations are way off, 1000km/h for 3,700M should take 3-4 seconds surely? If it's going to take you 13 seconds, you're Speed over ground would be around 270 KM/H.

 

If it took you 7-8 seconds, your SOG would be around 438 KM/H

 

If you were flying at 100 KM/H it would take you 35 seconds.

 

Was the 1000 KM/H a typo??

[lemoen]

I think your calculations are way off, 1000km/h for 3,700M should take 3-4 seconds surely? If it's going to take you 13 seconds, you're Speed over ground would be around 270 KM/H.

 

If it took you 7-8 seconds, your SOG would be around 438 KM/H

 

If you were flying at 100 KM/H it would take you 35 seconds.

 

Was the 1000 KM/H a typo??

 

 

1000 km /h = 1000 000m / h = 1 000 000 m / 3600s = 277m/s

 

 

t = d / v = 3400 / 277 ~ 13s

[Schmidtfire]

Thanks for bringing this up. Im not a technical expert on this subject, so I can only go by feel. I had a discussion with my brother and we also have found that the sense of speed seems off. Try flying low level, full afternurner, then approach and pass a single tree. It feels very very slow passing by.

 

Another thing is that distance in DCS seems not to scale properly with objects. Objects that appears close is actually a lot further away. Just sitting in the aircraft on runway I often ask myself if the height and scale of the world around me is correct.

 

With that said, I still love 2.5! Good job ED.

Edited February 6, 2018 by Schmidtfire

[Oban]

1000 km /h = 1000 000m / h = 1 000 000 m / 3600s = 277m/s

 

 

t = d / v = 3400 / 277 ~ 13s

 

Ahhhhh yes, I see where that comes from now, I took the raw speed, and never converted it down.. no wonder my land nav skills were always crap!!

[SUNTSAG]

I have tried low level flight at speed in the Harrier on both the new 2.5 and Normandy maps, with the standard FOV. It is like night and day between the two maps IMHO.

 

In Normandy you get a greater sense of speed at low level than in the new 2.5 Caucasus. The same was also true of 1.58 so I hope future tweaks improve this. Its still early days for 2.5 so only time will tell. Cheers.

[ST0RM]

This was exactly my first impression, upon trying 2.5 yesterday. In the Gazelle, low level, it felt like I was walking. Harrier and F-5 at 400kts at 500ft through the mountains, again really slow.

 

I understand the FOV aspect, but that is not realistic. And in the Rift, difficult.

 

This needs more attention.

[Oban]

So the feeling of speed was better in 1.58/2.2 then?

[dali]

bbrz, thanks, in my case it also seems that round 90 deg view is closest to real life, as you correctly mention, peripheral vision can't be simulated just by setting the FOV to 120 deg. Thanks for your speed test, I guess my timing was off, it was just a quick test. I was 99% sure, that they got the physical part correct (ie moving of objects in space).

[dali]

I have tried low level flight at speed in the Harrier on both the new 2.5 and Normandy maps, with the standard FOV. It is like night and day between the two maps IMHO.

 

In Normandy you get a greater sense of speed at low level than in the new 2.5 Caucasus. The same was also true of 1.58 so I hope future tweaks improve this. Its still early days for 2.5 so only time will tell. Cheers.

 

funny, after I read your post, I went and tried it out. I don't know if I'm imagining, but it realy seems that Normandy moves faster under my plane :)

[Bananimal]

Hey gents, see this thread. The issue is the size of the trees. They are waaaaaaay too big on the Caucasus map. I've created a mod that reduces the tree sizes to great effect. Speed an altitude are on point with the mod.

 

You can choose between 30, 40, 50, 60, 70, and 80 percent reductions with the mod. I use the 80% reduction as it looks about perfect in terms of scale. JSGME ready.

 

https://forums.eagle.ru/showthread.php?p=3385793#post3385793

Edited February 7, 2018 by Bananimal

[draconus]

Speed/distance test Caucasus area, F-15C, 400ft MSL.

1NM 200ktas = ~17.6sec = ok

2NM 400ktas = ~17.6sec = ok

1NM 600ktas = ~ 6.0sec = ok

I confirm by my own test in F-15C at Sukhumi. The ruler in ME says the runway is almost exactly 2nm. My flyby with constant 513kts ground speed was around 14s and that is correct. The main factor of speed perception is FOV and details on the ground.

[Sideslip]

Hey gents, see this thread. The issue is the size of the trees. They are waaaaaaay too big on the Caucasus map.

 

I do think that some of the trees around the cities are a little tall, but trees that are hundreds of years old tend to be quite tall. It seems some of the tallest trees in the built up areas are 5 stories tall, which would only be about 60ft which is pretty normal for an old tree. The trees are spawned at different heights, some look quite small. If anything the max height in built-up areas should be reduced a little, but the rest aren't too abnormal.

[NineLine]

I did some quick runs in the L-39, trying to get the camera as close to the vids as possible, and to be totally honest, I dont see much difference. The ground closest to the aircraft looks as fast as I would expect, and as you look further back behind the aircraft the effect is lessened. This was brought up with Wags Hornet Vid before 2.5 was released, and real world vid footage showed it was pretty accurate there as well.

 

The size of the trees... dunno if I agree with that worries about that, I know we get some pretty big trees here in BC, I am sure they do in Georgia as well.

[Raz_Specter]

IMPO flying the Harrier at low level is a little lethargic at 500 in 2.5, doesn't really feel as though you are going fast at all. I have tried both TrackIR and the rift, while the rift does feel a little faster TrackIR doesnt.

[dali]

@SiThSpAwN: since guys have done some tests and confirmed that speeds are OK (of which I had no doubts, just my measuring was a bit sloppy), but there is definitely a problem with rendering...or better to say with how "view" in the cockpit works. Human eye has constant FOV, it is "changing" only by focusing on particular details, but the camera view and FOV is just zoom in/out. Eye retains the FOV, only the details are blurred (like when you look at instrument, FOV is still the same, but as focus is narrowed, there is more of the blur area left and right of each eye. I think developers should have a more look into it, as default view (and FOV) are causing the feeling of lethargic flight. Current view from the cockpit is rendering the terrain as if it seen from above, not from the forward moving object (planet). I think here lays the foundation of the problem (unless somebody from ED proves me wrong).

[draconus]

developers should have a more look into it

I _see_ what you did there ;)

There's really nothing you can do about that. Rendering is fine but it has it's limits because it's basically converting 3d scene into 2d screen. And it adds distortions also. Maybe 3 monitors config helps?

Now you can only change your FOV (biggest factor but there are always some distortions the bigger the fov). Or head position but that will cause you to lose HUD allignment.

[sedenion]

I know that FOV increases the perception, but FOV is, as I see it in DCS, just a zoom in/out. So it mimics the camera FOV, not the eye.

 

This is the same... FOV (Field Of View) is an angle of a cone/frustum through objects are projected on a surface (this is what we call Perspective). What DCS (or any 3D engine) does, is to project the world into a flat rectangle (your screen), like a camera. You cannot simulate a "eye FOV" on a screen, because your eyes are not flat, but round, your brain make a lot of thing to let you appreciate the world as wide view.

 

When you play DCS, its like seeing the world (DCS's world) through a very small window. If you want the DCS Fov to be almost correct considering your actual eye's field of view and screen size, you have to set the FOV to something between 15° and 30°... You will only have a HUD, a very small part of the cockpit...

[PeaceSells]

Have you tried flying the F-15 low and fast over Las Vegas? I think the sensation of speed is high there...

[dali]

What is the default FOV in your opinion? Having done quite a few low level runs IRL I certainly don't see anything 'lethargic' in DCS...

 

in DCS? between 80-90 deg. I know that you can't fit world on flat screen without distortion. What would solve this would be adding a feature, which would introduce motion blur at the edges of the smaller FOV (60 deg for instance). But I think that performance impact would be too great to be feasable. Maybe in few years? :)

 

Chaning FOV is not zoom in/out per se, as human eye is very adaptable organ and it doesn't operate simply like camera zoom. FOV of the human eye is constant, because we have stereoscopic sight with eyes that turn simultaneously in same direction.

 

As far as I understand how view is done in DCS now is that view centrepoint is fixed where head of the pilot would be and normal view (default one) is actualy zoom in, for purpose of course, so one can read the HUD and instruments. In real life eye is capable of focusing in infinity in order to see through HUD and in the same time forcus on the display itself, and then quickly glancing in the cockpit, focusing on one instrument and quickly back into infity looking outside.

 

Bottom line of my original post in this matter is, that because of how view is done in DCS, I have problems with perception of the speed by judging how fast the world is moving beneith the airplane. When in airplane, It is easy to judge speed by looking out :)

[dali]

at the beginning of the video I was not sure...but as it progressed, I was more and more convinced that this is indeed good thing! thanks for heads up!