How Large are the Fireballs of Detonating Shells? : Lies from Movie Cameras

[dkoor]

went beta release  we all can test it.

 

I hope it will not turn to  MG151/20 like in UBI forum  again. 

 

man.... I miss my MK108/30

Haha, ironically all those MG151/20 whines turned out to be right on trail... pods were doing significantly more damage than those mounted in noses or in FW-190 wings... someone forgot to put in the minengeschosses, good it only took few years to rectify that  .

 

And yeah, I agree on Mk108 that is one hell of a cannon, for the most part I preferred it to the MG151/20s.

There is this sound thing about that cannon which makes an unsuspecting victim feeling like an illuminated rabbit on a highway at night...

Dang...that looks pretty darn good.....

Thanks!

Gotta few more of those, but I think the Fw one and this, dive bombing Ju-87s turned out best:

 

[Graawl]

Nice and informative thread !

It is a good example of how difficult it can be to properly implement visual effects in a sim.

 

I personnaly do not have any problem with big explosions, they happened some times, there are lots of pilot's testimonies about surprisingly big fireballs.

As long as some more subtle effects are present, like the long slender flame we can see in some guncams. [edit] That's not an explosion though.... but you catch my drift [/edit]

 

And big FTW explosions are fun AND rewarding for the one causing them :D

 

But isn't the OP about explosions being not as big as they should be?

Edited October 20, 2013 by Graawl

[FuriousMeow]

I believe that you actually disagree, as the OP clearly declares the faults of the slow speed gun cams as you do also.

The human eye might not be able to catch the details as a high speed camera, but shurely the light effects.

 

No, because high or low speed - cameras are not an accurate representation. They can catch too much light with high speed recording, they can be subject to artifacting where something shows up but truly isn't, and various other issues with light. Watching NASA videos of space, there are giant orbs of light and other artifacts that appear to be UFOs but are not present/smaller/different shapes than what is present in the recorded version.

 

Cameras/recording devices at any speed are not a good source for how it actually looks.

[FuriousMeow]

From my time in, I fired a Mk-47 GL at dummy tanks (real tanks hulls) at 250 to 500 meters. All that happened was a bright white flash at impact and a little smoke. It wasn't huge, it wasn't an impressive fireball - just flash and gone.

[bckstk]

As has been mentioned above, why make effects visible as perceived by a high speed camera? I don't think saying what a high speed camera sees makes what I can see 'a lie'. Its just a matter of perception. Why not model the sim in the infrared spectrum? That would yield different results, too.

 

Honestly, for me, big explosions = cool, and I admire your thoroughness, but I just disagree with your main idea that the high speed camera's view is the 'real' one.

 

Anyway, carry on...

 

In my original draft I talked about thoughts like this, but for the sake of reducing the length of my post, I deleted it.

 

Some people may have this idea: if the normal speed camera cannot see the the fireball which can be detected only by the high speed camera, then our human eyes cannot see it either. Or simply, that the human eye cannot see what the high-speed camera can. That is an interesting point, but it is one which is full of confusion and misunderstanding.

 

1) It is not something that can ONLY be seen by the high speed camera. The same fireball that one normal-speed camera fails to catch can perfectly be seen by another normal-speed camera, no high-speed camera whatsoever being involved here.

 

See the shot at 03m:07s, which I discussed at the beginning of post #2. (The pictures needed are attached below again.) For this shot, the first camera tells a lie, saying there is no fireball; by contrast, the second normal camera doesn't tell that lie. The difference is merely that only the second camera happens to keep its eye open at the moment when the detonation happens. If your eyes are not blinking at that moment, you can see that fireball too; that's by no means the special privilege of the high-speed camera.

 

 

 

 

2) No part of my dicussion at the top of this thread involves processes that can only be seen by the high-speed camera. I used the high speed camera's view to demonstrate that there is indeed a fireball where the normal camera says there is not...If there were other lucky normal-speed cameras to catch the fireballs, as in the case above, the high-speed camera's view would not have been really needed.

 

If there is a fireball, your human eye can see it, and can see the full-grown one. You can see a camera flash (for photography), can't you? That flash is extremely short, but still easy to dectect by the human eye. Detonation fireballs are much slower processes compared with camera flashes for photography. By the way, the human eye does not need the instensity of the camera flash to detect a flash of an equal temporal length.

 

3) I've never said that any sim should model the high-speed camera's view.

Edited October 21, 2013 by DeepSky

[SKG51_robtek]

No, because high or low speed - cameras are not an accurate representation. They can catch too much light with high speed recording, they can be subject to artifacting where something shows up but truly isn't, and various other issues with light. Watching NASA videos of space, there are giant orbs of light and other artifacts that appear to be UFOs but are not present/smaller/different shapes than what is present in the recorded version.

 

Cameras/recording devices at any speed are not a good source for how it actually looks.

I always thought , that with high speed recording the problem is to get enough light to expose the picture in the short time available.

Otherwise, they are the only storable way to save those impressions.

[bckstk]

I believe that you actually disagree, as the OP clearly declares the faults of the slow speed gun cams as you do also.

The human eye might not be able to catch the details as a high speed camera, but shurely the light effects.

 

[bckstk]

From my time in, I fired a Mk-47 GL at dummy tanks (real tanks hulls) at 250 to 500 meters. All that happened was a bright white flash at impact and a little smoke. It wasn't huge, it wasn't an impressive fireball - just flash and gone.

 

Personal impressions are difficult to interpret, because of vagueness ('small', 'huge', 'how far', etc).

Just a few thoughts. Sunlight can change the colour of the flash.     Looked at from far away, things are much smaller.      I would call that flash a white fireball; if it were indeed very small, you wouldn't have seen it that easily at that distance. If the sunlight is strong, it makes the flash less visible, especially at long distances.

[bckstk]

I always thought , that with high speed recording the problem is to get enough light to expose the picture in the short time available.

Otherwise, they are the only storable way to save those impressions.

 

Exactly. That is why a lot of high speed recordings are black-and-white, if I am not mistaken.

[JtD]

They are also cheaper. We've got both, black and white and colour high speed cameras, with the same sufficient resolution and fps for our purpose. So technically both are possible, but colour was a lot more expensive. I think that, at least with modern digital cameras, the limit is not so much about exposure but more about data storage. Full HD at 1000fps is a lot of data in a very short time.

[Wind]

Exactly. That is why a lot of high speed recordings are black-and-white, if I am not mistaken.

 

Not only that, but many of the high speed cameras are made sensetive for Infrared spectrum as well.

 

And it is here where the problems arise : What human eye, video camera or HS IR cameras see, can be very,very different.

 

The difference, say in percieved size of a explosion, between human eye and IR camera can be huge.

So which one is more True?

Both are, obviously.

And should someone model explosions for the game based on IR camera alone? Hell no.

 

That comes down to original posters videos, with what kind of camera are they shot with?

I have shot quite a bit of moving images, 8/16/35mm, RED, 1/5/7D, phantom and I can not say for 100% certainty with

what cam the BW materiel is shot with.

But, if it would come down to push and shove, my bet would be Phantom IR300.

 

A infrared sensetive high speed cam...

[mazex]

Well, here is one that I guess most of you have seen of a Hispano firing..

 

http://www.youtube.com/watch?v=Oc9E8_ZuESQ

 

Not too good quality and what the camera sees is not the same as the eye... 

 

 

[FuriousMeow]

I always thought , that with high speed recording the problem is to get enough light to expose the picture in the short time available.

Otherwise, they are the only storable way to save those impressions.

 

Yes, over exposure is where too much light is let in over a long period of time.

 

However, light can be controlled through the optics as well - much the same way the human eye's pupil/iris functions. So you can over-expose just by full dilation of the lense.

Edited October 21, 2013 by FuriousMeow

[Sternjaeger]

guys, have a look at the video I've posted on the previous page: aircraft 50 cal shooting mixed rounds (the incendiaries are the ones that flash and spark) against a metal target, it doesn't get any more accurate than that!

Edited October 22, 2013 by Sternjaeger

[VBF-12_Stick-95]

Are there any first hand accounts by pilots discussing what is seen in gun camera footage versus what they were able to see?

[bckstk]

Not only that, but many of the high speed cameras are made sensetive for Infrared spectrum as well.

 

And it is here where the problems arise : What human eye, video camera or HS IR cameras see, can be very,very different.

 

The difference, say in percieved size of a explosion, between human eye and IR camera can be huge.

So which one is more True?

Both are, obviously.

And should someone model explosions for the game based on IR camera alone? Hell no.

 

That comes down to original posters videos, with what kind of camera are they shot with?

I have shot quite a bit of moving images, 8/16/35mm, RED, 1/5/7D, phantom and I can not say for 100% certainty with

what cam the BW materiel is shot with.

But, if it would come down to push and shove, my bet would be Phantom IR300.

 

A infrared sensetive high speed cam...

 

Please have a look at my explanation at post #46. Then, I hope it is not difficult to understand this: the high-speed recordings do not have to be referred to if we have a large number of normal-speed cameras to simultaneously record every single detonation. Some cameras are going to fail to see the fireball altogether, some are going to see a small fireball, and only a few 'lucky' cameras are going to capture the full-sized fireball. 

 

And the Infrared issue. Before writing those posts at the top of this thread, I checked lots of Near-Infrared (NIR) photos and NIR recordings and compared them with the black-and-white recordings in this video, and I found they were very different. What do leaves and grass look like in an NIR red image? Here is an example:

 

 

In the video I posted, the grass and some dark short bushes in the black-and-white sections simply do not look that way, but look just as in normal black-and-white photography. 

 

Please look at the following screenshots. Is there any significant difference between the two scenes, apart from the slightly stronger contrast in the first image? Actually the first image was created by desaturating the colour recording at 01m:59s. Is there in the second image any recognizable infrared-ness?

 

 

Even if NIR recording is used in the video in question, does it really matter in the discussion of fireballs' existence and their sizes? It doesn't, because it does not give a new fireball size anyway.

 

As a matter of fact, in the original posts I pointed out some corresponding moments in normal-speed and high-speed recordings, so it can be checked whether what you called "IR recording" gives the same fireball size as does the normal speed recording.

 

You can also check the high-speed camera shots and the lucky, normal-speed camera shots of the same fireball at 02m:04s, to see if the two recordings give drastically different sizes of the same fireball. The normal speed camera was lucky in this case to catch almost the full size of the fireball. As you can see,  the fireball by high-speed recording has the same size. 

 

 

What human eye, video camera or HS IR cameras see, can be very,very different.

 

I can't agree more... But let's just don't stop at that knowledge ; it is more important to know where they are different and where they are not.

Edited October 25, 2013 by DeepSky

[79_vRAF_Friendly_flyer]

OP have you ever watched something like a cannon round out hands grenade explode in person?

I'm sure there are others here that have...

 

I have. The fireball/flash is not always visible, even though you know it must be there. I agree with DeepSky that the camera likely often misses flashes, but so does the human eye!

Edited October 25, 2013 by 79_vRAF_Friendly_flyer

[bckstk]

Yes, over exposure is where too much light is let in over a long period of time.

 

However, light can be controlled through the optics as well - much the same way the human eye's pupil/iris functions. So you can over-expose just by full dilation of the lense.  

 

The exposure time of each frame of a high-speed camera can be 1/10000th of the exposure of a normal camera. If dilation of the lens is adopted as a method of increasing exposure in high-speed recording, then the lens of the high-speed camera should be 10000 times as large as that of the normal-speed camera - that's over 300 metres! 

 

Anyway, there might be over exposure in high-speed recording as well, but that is an issue belonging to the cinematographer's skill, not to high-speed cinematography per se.  

 

[bckstk]

I have. The fireball/flash is not always visible, even though you know it must be there. I agree with DeepSky that the camera likely often misses flashes, but so does the human eye!

 

Strong sunlight and a long distance between you and the explosion can make the fireball visibility decrease, and even make it smaller. The orange outer part of the fireball can become invisible in the daytime if you look at it from far away -- that is the reason, or at least one of the most important reasons, why many claim that the 'flashes' are white. The orange (or red) outer part of a fireball is the weaker part of it in terms of light intensity; so, from far away, it is likely to see only the core of the fireball, which is the central whitish part of it. 

 

 

 

Incidentally, one can hold a lit candle or cigarette lighter and see how part of its flame can become invisible against a bright background.

 

 

~~~~~~~~~

 

There are a few questions, always overlooked, for simmers that claim to know from personal experience what shell explosions really look like:

 

- Did you look at the explosions within 20 metres or 30 metres of them? Did you observe in person the explosions at the full spectrum of distances, from 1000 metres to 9 metres (yes, I mean 9, since it is possible in WWII style air combat)?

 

( If you haven't looked at the explosion of a cetain type of shell from, say, 30 metres away, how can you claim to know what the explosion will look like within 30 metres? )

 

- Did you observe them in every hour of the day?  

 

- Did you observe the shells hitting all kinds of material? 

 

- Did the shell (or even the grenade) you watched have the same explosive filling, and the same casing, as WWII aircraft cannon shells? 

 

- (As a joke, did you blink your eyes when watching? )

 

If a person's experiences have not covered all those possibilities, then can he say that he knows for certain about  explosion visual effects under all different conditions (distances, times of day, target material, shell specifications, etc)? Why must all explosions always have only that particular visual effect which he happened to see.

 

I'm afraid people may tend to generalise, believing the special cases that they have experienced to be universal. 

 

You can't see a person's nose if he or she is 50 metres from you; in other words, visually they have no nose at that distance, and this is what everyone sees with their eyes. But you really do not expect any game to draw a person with no nose when he or she is face to face with you.

  

Does anyone want a WWII flight sim in which the explosion effects on an aircraft 30 metres away are created according to a simmer's description of certain 'modern' explosions he once saw from 300 metres away? 

 

 

Edited October 26, 2013 by DeepSky

[79_vRAF_Friendly_flyer]

 If a person's experiences have not covered all those possibilities, then can he say that he knows for certain about  explosion visual effects under all different conditions (distances, times of day, target material, shell specifications, etc)? Why must all explosions always have only that particular visual effect which he happened to see. 

 

I'm afraid people may tend to generalise, believing the special cases that they have experienced to be universal. 

 

Notice is said "sometimes"...

 

Granted, the explosions I saw was in the 1980s and -90s, so the explosives may have been different from those of 2nd WW weapons. I have seen several weapons at work, including grenades and RPGs. Sometimes they had small fireballs, sometimes just flashes, and sometimes no discernible light effects at all, just smoke and a bang. The lesson I took away was that the hit effects re extremely variable, and not at all like in the movies (well, since 1980s films were the comparison...).