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View Full Version : Just a Random though on canopy refraction, and the breadth of impact it would have



XyZspineZyX
06-17-2003, 03:01 AM
I just occured to me, that if refreaction were to be included in the 190's forwad windscreen, it would have to be included on every pane of transparent material in the game, and applied according to the diffractions indexes of that material and composites. Considering how optically pure curves were still under development through most of the war that would have a sever impact on nearly every aircraft currently in the game.

While the 190 may gain a few degrees in downward visibility, it would also gain two very large distortion lines along the rear/side canopy, which would distort aircraft on your six. The 109 would also lose rearward visibility, again, allong the bend in the curve n the canopy. The He-111 would suffer the most, having distortion across nearly the entire aircraft's nose glazing. The B-29 suffered from the same problem, and a signifignat number were lost to landing accidents due to the distorted forward view.

It gets even better when binocular vision is added in. You eyes doesn't ignore a distorted immage in one eye; they try to reconcile the distorted immage with the correct one, resulting in even greater distortion. Essentially, the distortion ends up covering twice the area.

Basically, what including refraction gives in one area, it takes away in another. Now, once personal computers are up to it, I see no problem in including light refraction algorithms into the game, provided sufficent documetns exsist to record the diffraction indexes of the materials used. None of them were truely optically pure, even if many of them were close.

Truely it has only been in the past few years we have even been able to produce medical lenses that are very close to optically pure, and those are *extremely* expensive to make, and they still aren't perfectly optically pure. Back in WWII, optics were still in their infancy, and aircraft got nowhere near medical grade glazings on their canopies. They all had distortions to some degree. The arguments about that stuff are going to be nasty too. Consider that an eigth of an inch can cause signifignat optical distortions, depending on where it is applied or removed, then try to find design records that agree to that level of precision, and one can see what I mean.

Harry Voyager

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XyZspineZyX
06-17-2003, 03:01 AM
I just occured to me, that if refreaction were to be included in the 190's forwad windscreen, it would have to be included on every pane of transparent material in the game, and applied according to the diffractions indexes of that material and composites. Considering how optically pure curves were still under development through most of the war that would have a sever impact on nearly every aircraft currently in the game.

While the 190 may gain a few degrees in downward visibility, it would also gain two very large distortion lines along the rear/side canopy, which would distort aircraft on your six. The 109 would also lose rearward visibility, again, allong the bend in the curve n the canopy. The He-111 would suffer the most, having distortion across nearly the entire aircraft's nose glazing. The B-29 suffered from the same problem, and a signifignat number were lost to landing accidents due to the distorted forward view.

It gets even better when binocular vision is added in. You eyes doesn't ignore a distorted immage in one eye; they try to reconcile the distorted immage with the correct one, resulting in even greater distortion. Essentially, the distortion ends up covering twice the area.

Basically, what including refraction gives in one area, it takes away in another. Now, once personal computers are up to it, I see no problem in including light refraction algorithms into the game, provided sufficent documetns exsist to record the diffraction indexes of the materials used. None of them were truely optically pure, even if many of them were close.

Truely it has only been in the past few years we have even been able to produce medical lenses that are very close to optically pure, and those are *extremely* expensive to make, and they still aren't perfectly optically pure. Back in WWII, optics were still in their infancy, and aircraft got nowhere near medical grade glazings on their canopies. They all had distortions to some degree. The arguments about that stuff are going to be nasty too. Consider that an eigth of an inch can cause signifignat optical distortions, depending on where it is applied or removed, then try to find design records that agree to that level of precision, and one can see what I mean.

Harry Voyager

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XyZspineZyX
06-17-2003, 08:01 AM
There's a huge difference between asking that the bottom of the revi not be occluded and asking for every little nuance to be ray traced.

Maybe most people don't realize what will happen to the view angle over the nose. You see, the pilot POV now is a bit high to get the angle we see and if the bar is lowered then the POV can be moved down some as well... total view angle would not change and may lessen and still the whole circle be unblocked. Anyone asking for more view, period, is wrong and perhaps looking for a gimmie or more likely feeling cheated without taking the time to figure the details out.

Move the bar, lower the point of view, angle is same, picture from inside is cleaner, no problem.


Neal

XyZspineZyX
06-17-2003, 08:28 AM
I also differ. You will be surprised how much a thick armored glass can refract and appear thinner almost comparable to a normal glass. However, normal glass and curved-plexiglass like materials (like plane canopies) show minimal-to-none refraction effects.

However, the curved canopies do distort badly, due to un-even surface, creating distortions of the view, but no closer or larger, but smeared. A bit like those "funny mirrors" you see on fun-fairs. Very different to refraction. They also create a mirror effect when the light bounces through them, blinding the pilot and making it very hard to see through. (I tried to create this effect -distirtion-reflexion- on my He-111. see how it looks when the sun strikes frontal).

I think if refraction is proven to be a factor in the vision of 190 (which is screaming for it) or the La and Yak9, it is only three planes to do (I think).

I am not asking to create all the visual laws that happen when looking though a glass. that would be a real task. but reducing the thickness of 3-4 planes that should. This could be an easy task on 3D, and no programming.

<img src=http://www.silence.plus.com/xanty/stuff/fb_falco.jpg>

XyZspineZyX
06-17-2003, 09:11 AM
Harry has a valid point. We shouldn't try to pick the "good things" about refraction, and at the same time ignore the bad things it brought with it.

XyZspineZyX
06-17-2003, 02:15 PM
Let's have dust and bugs in the air then with realistic flight for the bugs, or we can't have air.

This is a matter of something blocking the lower part of the gunsight, not a minor light and angle dependant effect off to the side. Gunsight view is very important and moreso when the choice of views is limited, but there's only really 1 view through a gunsight so that makes this a non-moot issue. It is that freaking simple so don't make nothing of something.

There are limits to realism in PC sims. The most important places to get realism are the working parts. Everything else is nice eye candy. A lot of us happen to feel that the view through the gunsights is a working part of a combat flight sim. Please, tell me it's not important.


Neal

XyZspineZyX
06-17-2003, 02:27 PM
Having the lower frame simple cut away without any other effect of refraction anywhere in the sim is as unrealistic as having it there.

XyZspineZyX
06-17-2003, 02:45 PM
but atleast that would be more realistic solution than we have now.

XyZspineZyX
06-17-2003, 03:14 PM
IJG54_Nowi wrote:
- Having the lower frame simple cut away without any
- other effect of refraction anywhere in the sim is as
- unrealistic as having it there.
-
-

with that "all or nothing" approach,i doubt we would be even playing those old Atari tennis games now,more like pin the tail on the donkey,then again someone would have had to invent fire bypass the bronze age,ironage and jumped straight to high grade steel for the pin,invent spinning/weaving and a knot for the blindfold etc etc




<img src=http://www.luftwaffepics.com/LCBW/FW190-D9-29_small.jpg>
"yeah whatever"

XyZspineZyX
06-17-2003, 06:16 PM
Cant some of you hear what Xanty is saying? Just kidding.



Refraction only becomes significant with:

- Thick glass
- angled glass- remember if the glass is not angled, there is no refraction of the light passing thru it, no matter what the thickness.



In other areas the effects are negligible, or none at all.

Therefore, there are only a few planes were function as a fighter is significantly effected by refraction.


Lets not make it more complicated than it really is.

Widgeon

XyZspineZyX
06-17-2003, 06:52 PM
Modelling dynamic cockpit refraction will set flight sim grafix back by about 6 years because of the extra computations. Oleg, stay awaw from this thread.


IGJ54:::
---Having the lower frame simple cut away without any other
---effect of refraction anywhere in the sim is as
---unrealistic as having it there.

If the Fw designers used refraction to "lower" the bar, than statically lowering the bar would be a way to model that. I have been looking around a little for reference on this. Can anybody show link that references use of refraction by the Fw designers?

I'd rather see more programming put into AI and modelling real dynamic weather.

We forget, all models are approximations. /i/smilies/16x16_smiley-happy.gif





Message Edited on 06/17/0305:54PM by LEXX_Luthor

XyZspineZyX
06-17-2003, 09:50 PM
I simple dont want "selective realism".

If we agree that refraction and it's influence on the front view are an important detail for realism, then the bad influence at the top bar, and the back of the canopys is also an important detail for realism. We shouldn't just pick the good parts.

XyZspineZyX
06-17-2003, 10:00 PM
Nowi, you didn`t read Xantys posts, did you?


And if you did, and obviously disgree with him, may I kindly ask you how many planes and cockpits YOU already modelled for IL2 and FB?

I would know of none, but I might be wrong here?


I wouldn`t ask this question if I wouldn`t find it disturbing that you obviously feel the need to jump in nearly every thread here, never presenting facts, only your "opinions".

XyZspineZyX
06-17-2003, 10:14 PM
I present facts enough, and often my opinion, that shouldn't be a problem for you, hmm?

Xanty seems to agree that "glass modeling" has a lot of other problems than just refraction. I dont think it's realistic to give certain planes their great historical frontview while ignoring the historical problems their curved canopys bring with them. Either there is glass, or there is no glass.

XyZspineZyX
06-17-2003, 10:42 PM
IJG54_Nowi wrote:

- Xanty seems to agree that...etc etc



So you did read Xantys post, but you did NOT understand it.


Thank you for pointing that out.

So far to your "opinions".


Enough of arguing, thank you.

XyZspineZyX
06-17-2003, 10:58 PM
WWMaxGunz wrote:

"Let's have dust and bugs in the air then with realistic flight for the bugs, or we can't have air.

This is a matter of something blocking the lower part of the gunsight, not a minor light and angle dependant effect off to the side. Gunsight view is very important and moreso when the choice of views is limited, but there's only really 1 view through a gunsight so that makes this a non-moot issue. It is that freaking simple so don't make nothing of something.

There are limits to realism in PC sims. The most important places to get realism are the working parts. Everything else is nice eye candy. A lot of us happen to feel that the view through the gunsights is a working part of a combat flight sim. Please, tell me it's not important.


Neal"

------------

Yep, sounds simple.

Unfortunatly, nothing is simple in this community. Even the obvious.

XyZspineZyX
06-17-2003, 11:22 PM
Xanty, I don't know the specifics of all the planes, but a quick Yahoo search turned up armor glass for the P39, P40, P47, P51, Me109, Me262(90mm!), Stuka, Hurricane, Buffalo (at least some models, not sure about Finnish), Lagg3 (at least some models, probably later models), Sturmovik. These are just the Il-2 aircraft that popped into my mind to check on, and it appears they all have some form of thick armoured glass in (or more commonly 'behind') the windscreen.

Again I don't have the exact figures, but most of these 'armoured windscreens' are 30mm+ thick, with at least a modest angle. I think its a great idea to try and model this into Il-2 FB somehow, and the FW190 being the only aircraft I fly given a choice I'd love to see it happen.

But, I just don't see how Oleg can, in good conscience, allow the 'feature' to be implemented for only a small selection of planes, without opening himself to huge criticism from the other 'aircraft camps'. And it appears to me to correctly 're-do' all of the model aircraft would require a considerable undertaking, much more than just a few aircraft.

XyZspineZyX
06-17-2003, 11:32 PM
Hi Lignite:

Please start up Il2:Fb and go each cockpit one by one and take note of all the ones you can see have a thick armor (flat glass) windscreen with thick frames that support it. This only on the frontal-sides of canopy (where is most critical). I did a rough stimation (from head) and I can say 190, La-5, Yak9. The rest have really thin frames (some seem way too thin).

lets not go nuts here. All I am thinking is that is such critical place a simulation of refraction is in order. Nothing more.

And those extremist, please let me remind you that most rusian planes had low quality curved canopies that gave poor vision (deformation, dark, dirt, deffects), and this seems not to be simulated either (only some). I would rather ask for a "clearer" (lighter) gunsight for the Yak9 than that revision of lack of realism.

And leave the flamethrowers at home. too many forestal fires on summer is costing us the planet. /i/smilies/16x16_man-wink.gif

<img src=http://www.silence.plus.com/xanty/stuff/fb_falco.jpg>

XyZspineZyX
06-17-2003, 11:47 PM
You compare hills to mountains.

In how many of those planes is the armor glass highly angled?

In how many of those planes is the gunsight set so low that without refraction part of the sight is blocked?

In how many of those planes is the refraction so much a part of the design that Oleg had to raise the pilots POV slightly to get the view angle over the nose without including refraction that he did, which exasperated the sight picture?

I guess the number drops, don't it? The ONLY sights I remember from the sim that are blocked anywhere are on FW190 variants. The only request is to move the block in a way that would simulate the perception of light passing through flat glass at a tight angle making the glass appear much thinner. Only because of a critical view in a tight place.

I would also like to see the pilots eye lowered at the same time to correct height which would keep the over the nose angle to what Oleg already has but with a clean view through the damned gunsight for deflection shots.


Neal

XyZspineZyX
06-17-2003, 11:52 PM
I also did a rough check by looking at the aircraft in FB, and will stand by my list above http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif . But I don't mean to argue, I really have nothing else to contribute. I know I can't say for sure, but I suspect Oleg may have quite a bit of knowledge on the subject. I have no doubt he'll make a decision, and if its 'yes' he'll surely give guidelines on which aircraft need what.

I completely agree that Refraction (even simple refraction of only the armoured windscreen) of aircraft glass had a significant (even if only of minor significance) impact on the cockpit view (and there for Situational Awareness), and that this refraction is not currently modeled in FB (as stated by Oleg). I also agree that with some work it could be simulated in FB. Here's to hoping it works out for the best: Cheers!

XyZspineZyX
06-17-2003, 11:55 PM
Please look at the thickness of the frame on the P-47 or LaGG Amathing how thin they are, no?. Or P-39 which seems to not have frames holding glass at all. Does it look to you like any of these has an armored thick glass? I think not. So either it isn't or they already accounted refraction in the view. Or it is incorrect and should be thickened.

<img src=http://www.silence.plus.com/xanty/stuff/fb_falco.jpg>

Message Edited on 06/18/0312:19AM by xanty

XyZspineZyX
06-19-2003, 05:06 AM
The defraction does not lower the bar, it shifts the immage. That's the real problem with modelling, and using such a view. What the pilot would see is a plane passes behind the vertical struts and seems to shift up several degrees, when infact it is still flying along the same path. It can be rather disorienting until you get used to it (much as bifocals take several weeks before you can get used to the multiple immages.)

The P-47 had, if I recall correctly, two panes of glass, joining at a narrow joint at the front, with a pane of armoured glass behind it. Looking out the front of that plane, everything goes through two panes, with different angles and refraction indexes. That was another thing the pilots complained about.

Most of the side panes in aircraft were not armoured, however, I recall that the high visibility hood on the late model 109's had an armoured glass headrest for the pilot, so when he would look over his shoulder, he would, again, be looking through two panes of glass, the armoured headrest, and the external canopy.

A basic rule of thumb for American aircraft is if the plane has a flat forward windscreen, then that windscreen is armoured glass, and the curved sections are not. Nearly every aircraft has at least one pane of thick armoured glass in it; the Il-2, to my knowledge, has even the side panes armoured.

Thing is, it is still hard to make even an unarmoured pane of curved glass optically pure. The technology is still being worked on, and in WWII it was a very new technology. Many pilots reported noticable distortions in the blown and bubble canopies.

The basic point I am trying to make, is if you try to account for diffraction in just one pane of one aircraft, you are shortchanging every other aircraft in the game. You really have to take into account the refraction effects on all glazings on all aircraft, in order to implement diffraction in a fair manner.

Now, don't get me wrong, I'd love to see it done some day, when personal computers can handle it, but that day is not now, and tweaking just one aircraft to account for just one facet of diffraction isn't going to cut it. It would be like giving the 109 Komerstadt, while requiring that all other aircraft have constant pitch propellers, simply becausse the computers couldn't handle automated adjustments across the board. We already have enough accusations of bias as it is.

Harry Voyager

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XyZspineZyX
06-19-2003, 05:23 AM
Folks, there is still considerable evidence that the Revi sightline is effectively mounted too low in the sim (both refraction and line of sight, plus the bar shouldn't be in the way.) Even the folks building replica 190's say it is off. The other planes generally lack this bewildering "feature." How many of you actually believe that this design flaw of the Revi mounting would have survived more than a few test pilot flights? It just doesn't smell right. All it would require is a slight shift upward in the gunsight mounting (I could make spacers or a new bracket and do it myself in an afternoon.) Unlike your "virtual pilot" head this would only effect sighting view, not giving you trouble with being too close to the crossbar...at other times. Even if the Revi sight line were so low, you would still not be obstructed by the bar of the glass. Again, if it were all you have to do as a designer to fix it is extend the front glass/frame down by about 1.5 inches in a pre-production mod. Anyone who has done equipment design can see how easy this is in real life.

XyZspineZyX
06-19-2003, 05:45 AM
If I may add, I have been in a P-51D with its bubble canopy, and in the P-80. The refraction distorts quite a bit, but the thing that really throws you off is REFLECTION!!!! On a furved surface, it will REALLY throw you off. Doing a roll in a F-16 with MODERN GLASS with LESS REFRACTION AND OPTIC'S made me SICK from the visuals, not from the motion. It was very hard to land that damn thing on a carrier deck with all the reflections dancing around on the canopy. UGH! Remembering it makes me sick.

Notice on this pic, the refraction quality of the modern thin plexyglass on the P-51. YOu can see it how it bends the shed in the backfround.

http://gibbageart.havagame.com/chino/images/PICT0020.JPG


Add to that the reflection inside, its all very disorentating.

Gib


"You dont win a war by dieing for your country. You win a war by making the other fool die for his country."

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