The online racing simulator
FOV - Sense of Speed
(148 posts, started )
i like the idea ... maybe its to distracting but ill reserve judgement until ive seen it in action

Quote from N I K I :i have no good idea for name

dui view maybe ?
#27 - Gaas
You are allready on name and scawen didint see it yet rofl...anyways fisheye view seems fine...ehehe
Slider called "FOV linearity" should make happy all the users.
The ones who don't like distortion on the edges will use 100% linearity, the others can apply more non-linearity.
btw on the topic of wide fovs ... id like to see a multi camera rendering option for non flat projection rendering as well
#30 - Juls
In fact I did some tests this way: recording with fraps, and using spherize filters in premiere. Lens distortion filter is not good, because it exactly distorts the view like FOV does...so you take a large FOV and use negative lens distortion and you get exactly the same picture than a narrower FOV.

Did not have time to do much tests, but it works.
It only allows to simulate cylindrical or spherical distortion, but it's better than nothing. It works two ways:
- with a large FOV, positive values for spherize will stretch the center and shrink sides...it allows to use a large FOV without a too small center. It reduces speed sense coming from large FOV but it still keeps more sense of speed than narrower FOV.
- with a narrow FOV, negative values for spherize will shrink the center and stretch sides...objects and textures accelerate when they reach view side. Starting from 40 degrees FOV, I get something feeling like 60 degrees FOV in center, and 90 degrees FOV on the sides (I talk about speed sense).

to avoid objects bending on the sides and view corners, I use horizontal+vertical spherize instead of spherical spherize filter.
Anyway, cylindrical distortion is a bit brutal...70% of view is unchanged, and two narrow bands are heavily distorted...
In opposite to any guys here said, the lack of sense of speed is more about LFS than others simulators.

rFactor has a much better sense of speed using artifacts like wheel (force feedback) and cockpit (graphical) vibration and a fullbodied sound.

The Juls idea is a great idea and makes very sense.

The idea is simple and I have used the same principle to have a better impression of speed in LFS, but I don't work in the fov.

I simply turn off the cockpit draw. Once you have the track on the bottom of your screen the speed with which it crosses this end line is too much faster than the speed it crosses the line at the bottom of your windshield.

You can compare it with real life experience easyli: drive a kart and drive a truck or bus at same speed and you think that kart is too much faster than the truck, cause in the kart your eyes are next to the ground and there the impression is that the things passes too much faster.

What Juls is trying to make is move the same effect to lateral. You can get the same feel if you just go in a real car: put your two hands covering the lateral of your eyes and just look ahead, and you'll not figure how fast you are going. Then free your vision and turn your eyes to the side and the speed will increase a lot.

In fact, when the objects are in the edge of your fov, the speed tends to infinite, so, more larger fovs, more sense of speed obviously.

Despite of this idea makes sense, it is not supposed to be good in a practical way. Maybe it goes well with larger screens but not in a 4:3 monitor.

But it should be given a try to that. It sounds promising for some configurations.

And of course, along with this, a more deep sound and some fake effects could help a lot too (of course I know that canned effects are not in the plans, so I dispense any aggressive commentary from the LFS patrollers).
I suggested not too long ago a bit of a 'whooosh' sound as you drove past close-by stationary objects. Bit of a corny suggestion but I sometimes wonder what it would be like to have that sound inside LFS.

When I tried rFactor, the cockpit was very shaky, not like LFS at all. But when I paid attention to riding in fast moving taxis in Istanbul I realised that the shakes in LFS were much more realistic. Also, those very shakes can be quite annoying in the ISI sims. I'm sure you could 'simulate' more of a shake/rattle with the sounds. I think that's what's really missing...
#34 - Juls
Did you notice that space between signs before turns looks shorter than 50 meters? This is very visible with narrow FOV like 45 degrees...distances are sooo wrong (even if other cars look big like IRL).

As I increase FOV, signs look further from each other, and I need 115 degrees FOV on a 17 inchs LCD to have the right spacing between signs. Or 145 degrees using two monitors.

Of course, as soon as distances look right, speed too.

I think if we manage to bend a picture so center is not too small and distance between signs look right, it works.
I think a 3head solution can give this sense of speed better, but the idea is good, and if is not too hard to implement, maybe someone could give it a try... Scawen!!! any chance?
Quote :Did you notice that space between signs before turns looks shorter than 50 meters? This is very visible with narrow FOV like 45 degrees...distances are sooo wrong

yeah, but even in real life you always get funny visual distortions like that. I remember when I was young, and someone pointed out to me that the gap between the white lines in the road was 8 metres or something, and I truly didn't believe them- they looked more like 4 metres or so apart. Then I tested it and he was right!
#37 - Juls
Yes, of course, distorsions in real life. But I think we may all agree to say distances are wrong on screens with narrow FOV. And this is not only in sims.
Every onboard camera IRL does not give a proper sense of distance and speed. In fact every time the camera zooms in (=narrow FOV) and points toward incoming objects, it kills speed. I remember I was filming friends skiing quite fast...it looked fast as snails.
Looks like cameramen have hard time to find tricks that give back the sense of speed....avoid filming toward incoming objects (helicopter, crane...), avoid zooming, shaking camera, using fisheye lenses to fit a larger FOV into a 4:3 screen.

As you say, the only solution to get full sense of speed without distorsion is a large surrounding display or something approaching like triplehead2go or fresnel lenses or both. With such a display life is easy. But for others (99.9%?)
#38 - Juls
Sorry for the flood, I just realized such distorsion may be useful to increase sense of speed on small displays and for another purpose.

Default perspective used in sims is intended to be displayed on a flat display. It causes problem when you use multiple monitors and want to turn side monitors in order to get a surrounding display. Picture looks broken.

Cylindrical distorsion can be very useful for multi-monitor displays, because it creates the view required by such displays. Kegetys already implemented such a distorsion within softth (software triplehead).
Yesterday I got a new monitor. It is a Samsung 19" wide, and now playing at resolution of 1440 x 900 pixels the sense of speed has increased a lot.
I think a triple-head display, like those offered by Matrox and Quantum3D graphic adapters, could be a good solution for this problem and it wouldn't require any alteration of game code . Unfortunately it would be unreachable for most of us (costs) .

Goood, I'd love to try that out... http://www.youtube.com/watch?v=tGB6A5GyyEc
It needn't be expensive, three (or two if you have one) second hand 22" CRTs, £60 each, SoftTH is free software, second graphics card £25. If you're desk is big enough and you have a PCIe board and a hefty main graphics card, there's not that much stopping you.
You only concentrate on the primary (central) screen, the two other displays are for peripheral vision, immersion and sense of speed.
#43 - Juls
It seems that FOV is now a very discussed point.

I was still searching for an idea to improve the view, and I found something else. Main problem we have with FOV is that large FOV causes distorsion in objects with Y close from zero.
This is very visible within cockpit view: as you increase reasonably FOV, road remains mostly undistorted as it is far away, but car roof, doors and driver's arms are stretched and cover more and more the view. This happens because the projection used in game is perfect...in real life, wide angle lens always have a distorsion on the side which prevent this. For one time, perfection is a disadvantage

One way of getting rid of this is to use cylindrical or spherical distorsion, because this distorsion simulates a bit what happens in a wide angle lens or in our eye. For example the eyefish Quake simulates a view through a real, unperfect fisheye, and it looks far better for large FOV than the perfect DirectX projection.

Another way is to use different FOV. One for the world, one for the cockpit/car. It sounds strange but it works, because outside world and cockpit have different distances. World is mostly far away and large FOV is a better choice, it increases spatial awareness and sense of speed. Increase FOV and you see more.
On the contrary, cockpit is close, and you are inside of it...it looks nicer with lower FOV, closer from natural one.

Some driving simulators use a real car with a monitor on the windscreen.
In that case, cockpit is viewed using the natural FOV, and simulated environment uses another FOV adjusted for the monitor. It seems it does not cause any problem. Same for some flight simulators with real cockpit and monitor (there is a study like that where they use a real cockpit and they change the FOV on the display...from 22 degrees -natural FOV- to 80 degrees, and 80 degrees is better).


Here is an example. First a screenshot with 90 degrees FOV.
http://cracovia.free.fr/lfs_90_full.jpg

Then 130 degrees FOV (extreme setting). Better immersion for the road, but cockpit covers too much screen, door and arms are distorted.

http://cracovia.free.fr/lfs_130_full.jpg

Then a dual FOV screen. Road uses 130 degrees, and cockpit 90 degrees. You can see more road than in the 130 degrees FOV so the immersion is even better, and the cockpit looks better too.

http://cracovia.free.fr/lfs_130_90.jpg

With a dual FOV, as you see more road, you can get better immersion and sense of speed even for moderate road FOV. Increasing world FOV you can adjust sense of speed/distorsion, and reducing cockpit FOV you can decide if you want the cockpit to be more or less present/distorted.

Without moving point of view!
#44 - Gaas
good work..now if i would know how to do that dual FOV :/ just tried tu put FOV 130 and move view of eyes more front but its not same :/
#45 - Juls
It is like spherical/cylindrical distorsion...it has to be done by graphics engine. DirectX projection matrix has to be changed before car is displayed. The sample is an edited screenshot.

Anyway, I think this dual FOV thing can work nice with cars like in example (wheels are hidden by car interior), but it will not work with cars like LX and single seat because car wheels will look weird and seem to have lost contact with the road. Or maybe it will...Can't check that.

I think the spherical distorsion is the way to go. With a simple graphical step (mapping the rendered view on a 1:1 subdivided grid with U,V coordinates calculated from a sphere or anything else) it allows to see a nice large FOV without almost any distorsion, and even to create a view perfectly fitted for 3 monitor displays with side monitors turned a lot.

I have problem to make a nice movie of it, because the spherize filter in premiere lowers too much the resolution, but it seems it has some advantages. I can see a lot better on the sides (large FOV) and immersion, sense of speed seem better. To do it properly I need a movie in 1280*768...fraps stops at half this resolution.

I think most racing sims use rather classical tricks to improve immersion. Such an advanced feature, if it works nice, could be cutting edge.
#46 - FL!P
130 is probably a bit too much (to me, at least), but it looks like a good idea.
Haha, I'm going to revive this old thread!

I've played fisheye quake a little while back, and it popped into my head while I was racing a few nights ago.

The single most aggravating aspect of racing in a sim is the field of view. Even with a helmet on, when I'm autocrossing or at a track day, I still have decent situational awareness.

I'm all for utilizing either the fisheye or the cylinder distortion methods mentioned above. Yes, they do distort your view somewhat, but they satisfy the basic needs for racing:

1) The track ahead must be seen in high resolution to accurately judge oncoming features and obstacles. This is usually aided by a low fov, making the oncoming track appear larger, essentially allocating it a larger 'pixel budget'. If all we did was hotlap, then this would be okay.

2) Awareness of other cars in overtaking situations. It doesn't matter if they're distorted, so long as you have an idea of where they are in relation to you. Even a band of 20 - 40 pixels, that showed the area next to you in a sort of super-squished view would provide the cue so you don't turn into the fellow next to you.

3) Mirrors simply don't have the resolution they should. On a high resolution setup (1600x1200 and up) with some anisotropic filtering and anti aliasing, the forward view down the track is actually pretty good in terms of comparison to the level of detail your eyes can resolve in real life. The mirrors however, especially the 'in cockpit' ones are not that great. Why not grab the upper portion of the screen, and divide it into three zones, one for each mirror? You still have to shift your eyes up, but they become much more useful.

I still think that one of the best resolved simulations in terms of awareness was Falcon 3.0, in the track/eye view. It was criticized by some for being unrealistic, but it did a much better job of replicating the true awareness, as opposed to focusing on drawing a pretty picture.

Anyways, that's my 2 cents, love the game!
#48 - Juls
Just found this document, explaining how to obtain a curvilinear perspective with a simple vertex shader:
http://www.frost-art.com/Data/ ... ltimeCurvilinearPaper.pdf

It just requires to apply a very simple vertex shader. That's all. Even simpler than the idea with the pixel shader. Less computation.

This is exactly the idea I wanted to suggest. As you notice at the end of the document, the red sphere on the right stays undistorted, the center of the picture is more detailed, and for the same FOV it shows a lot more what happens on the sides.....better immersion because what you see on your flat screen is almost the same than on a curved screen.

As directx 10 forces devs to use vertex shaders for everything, I think they will soon give up the traditionnal projection matrix and use more and more corrected perspectives like that one.
Great link. This reminds me of the old fisheye mod for Quake I remember seeing about once. This seems more evenly balanced.
#50 - Juls
And it is a lot faster to compute, because this fisheye quake was rendering 3 or 6 views, and stitching them together. My first idea was similar: render a larger view, and then distort it using a pixel shader.

But with this vertex shader, it gives the same result with hundreds times less computation, as it only has to work on vertices.

For example sims like rFactor, GTL, GTR2 use shaders which can be edited...the perfect tool to check quickly what this effect looks like in a racing sim.

Concerning sense of speed, after comparing with other sims, now I am almost sure where the problem comes from: tracks in LFS are too large. Most of time 15 meters or more...even on fern bay which looks a bit narrow you can put 5 cars side by side.
It kills the sense of speed, 100 mph looks like 50mph, and it is very frustrating for beginners because they feel like they spin and slide at 30 mph.

FOV - Sense of Speed
(148 posts, started )
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