# NYT: GIMBAL Video of U.S. Navy Jet Encounter with Unknown Object

#### FatPhil

##### Senior Member.
easy. take pen and paper. draw a line of an inch exactly in the center. now rotate the paper on its center. the line rotates.

now draw a similar line but way next to it, near the edge (to make the effect more pronounced). rotate it on the paper's center as before. while the line in the center rotates, the line on the outside almost makes a looping / jumps rather than rotating.

the smudge on the window therefore needs to be super symmetrical in the center if it should have caused the glare during the rotation. if the smudge is more to the side, the glare would have done a looping / jumping rotation.

do you understand what i mean?

I do not accept your "the smudge on the window therefore needs to be super symmetrical" deduction. I don't even think your pencil line is an satisfactory analogue for a "smudge". Repeat the experiment with a big splash of tea on your piece of paper, rather than a small precise line, and we might have something closer to an analogue, and we might end up with the alternative deduction "the smudge on the window therefore needs to just be taking up a reasonably large area in front of the internal optics", which is a demand of almost immeasurable triviality.

Remember - Mick's already demonstrated that an imperceptible smear on a slide can mimic the effect seen - how is your pen line an analogue to that situation?

#### jackfrostvc

##### Senior Member
@Mick West

Would a oval heat source create an oval glare, or would it be round still?

#### Mick West

Staff member
Would a oval heat source create an oval glare, or would it be round still?

Depends how hot it is, and how large it is on screen.

Glare is the spreading of light around a bright object.

Glare starts out as the shape of the hot part of the object (when it's not really glare, just the shape), but as it gets hotter the more spread it is, and the more the shape is defined by other factors (aperture shape, diffraction - resulting in a 2D glare spread function, giving a shape)

#### Domzh

##### Active Member
I do not accept your "the smudge on the window therefore needs to be super symmetrical" deduction. I don't even think your pencil line is an satisfactory analogue for a "smudge". Repeat the experiment with a big splash of tea on your piece of paper, rather than a small precise line, and we might have something closer to an analogue, and we might end up with the alternative deduction "the smudge on the window therefore needs to just be taking up a reasonably large area in front of the internal optics", which is a demand of almost immeasurable triviality.

Remember - Mick's already demonstrated that an imperceptible smear on a slide can mimic the effect seen - how is your pen line an analogue to that situation?
we assume the flir technician Mick interviewed is correct, and that these glares could happen when theres smear over the front glass, ok?

the object is centered in the footage.

so if what we see is glare and not a physical object, creating a rotating illusion when the gimbal itself rotates, then my point still stands and the smear must create a centered, symmetrical glare or otherwise the glare wouldnt rotate in place but doing a little ark / semi loop.

the effect im pointing to still remains even with your splash of tea.

#### AmberRobot

##### Senior Member
we assume the flir technician Mick interviewed is correct, and that these glares could happen when theres smear over the front glass, ok?

the object is centered in the footage.

so if what we see is glare and not a physical object, creating a rotating illusion when the gimbal itself rotates, then my point still stands and the smear must create a centered, symmetrical glare or otherwise the glare wouldnt rotate in place but doing a little ark / semi loop.

the effect im pointing to still remains even with your splash of tea.
It sounds like you are assuming that the glare will be centered on the position of the smudge and not that the smudge will enhance the scattering of light around the position of bright objects in the field of view.

#### Domzh

##### Active Member
It sounds like you are assuming that the glare will be centered on the position of the smudge and not that the smudge will enhance the scattering of light around the position of bright objects in the field of view.
i dont know how i should explain this in any other way..

if you smudge the window and this smudge is the reason for glare to happen, then this glare WILL not be symmetrical AND centered over the object AND turn on its center axis without being perfectly centered and symmetrical.

IF the smudge isnt in the center and therefore the glare happens on an offset position to the center of the camera sensor then the glare / object WILL NOT rotate on its own axis AND stay in the same relation to the horizon / clouds EVEN IF the tiny mirrors inside the gymbal did center the object. The glare as a result of the offset positioned smudge on the outside window would "loop" / "arc" during the rotation of the gymbal.

dont fight positions, lets investigate what the Flir technician told Mick and how this should work out if his assumption should work.

he proposed this idea, not me. im just asking questions because i dont believe this explanation of the smudge works on the GIMBAL video. It might work to be the cause of assymetrical glares or artifacts on objects (coyotes maybe even) but i cant see how it could then turn on its own axis.

before the smudge idea the glare explanation was more plausible. adding this piece of information makes it rather unlikely.

and hence the technician said the glare happens when theres smudged windows and not on clean windows i would rule out the glare theory all together.

especially when we add the speed and trajectory from our newest findings to the equation, because now we have a plane that must fly sideways.

#### AmberRobot

##### Senior Member
i dont know how i should explain this in any other way..

if you smudge the window and this smudge is the reason for glare to happen, then this glare WILL not be symmetrical AND centered over the object AND turn on its center axis without being perfectly centered and symmetrical.

IF the smudge isnt in the center and therefore the glare happens on an offset position to the center of the camera sensor then the glare / object WILL NOT rotate on its own axis AND stay in the same relation to the horizon / clouds EVEN IF the tiny mirrors inside the gymbal did center the object. The glare as a result of the offset positioned smudge on the outside window would "loop" / "arc" during the rotation of the gymbal.
Ok. I think I understand what you are picturing now. You are contemplating a different effect than I am.

#### Domzh

##### Active Member
yes i know my thoughts are solely regarding the flir technicians feedback that he:

1) has seen flare/ glare rotate
2) in order for it to happen the window cant be clear but "whiped clear" with a sleeve resulting in a smudge (according to him thats what pilots do)

so if we assume that this is correct, the glare claim becomes extremely unlikely compared to the actual gimbal footage (the why as stated above in my previous post).

#### Buckaroo

##### Member
yes i know my thoughts are solely regarding the flir technicians feedback that he:

1) has seen flare/ glare rotate
2) in order for it to happen the window cant be clear but "whiped clear" with a sleeve resulting in a smudge (according to him thats what pilots do)

so if we assume that this is correct, the glare claim becomes extremely unlikely compared to the actual gimbal footage (the why as stated above in my previous post).
The glare is more likely to to have come from scattering off micro-scratches and imperfections across the entire aperture, like you'd find in an old windshield for example (all optical surfaces have them to some degree - you'd expect even more in the punishing environment of a FLIR pod), than a single isolated smudge caused by a negligent technician. In this case the glare would occur exactly as Mick has described.

#### Domzh

##### Active Member
The glare is more likely to to have come from scattering off micro-scratches and imperfections across the entire aperture, like you'd find in an old windshield for example (all optical surfaces have them to some degree - you'd expect even more in the punishing environment of a FLIR pod), than a single isolated smudge caused by a negligent technician. In this case the glare would occur exactly as Mick has described.
no i wouldnt agree

it would be the same effect that i have described. exchange smudge with scratch, doesnt make a difference.

if the glaring is caused on/due to the window, my explanation remains true imo

because now, as soon as the window rotates, you change the relative position on the camera sensor to the object emitting the IR rays.

at the very least the glare effect would shift from its previous position on the object and as i said most likely rotate in a curve.

if the software automatically centers the glare as the supposed object, it would still change its position relative to the horizon and clouds

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#### Itsme

##### Active Member
What you see when you look directly into a jet exhaust in IR is partly physical, partly glare.

The physical part is the exhaust plume which becomes very visible in IR. When you look "head-on" at that elongated hot cloud of gas, you are basically looking through a thick layer of hot air emitting lots of IR. That alone will look like a blob caused by glare, though in reality it is something physical.
The glare itself comes on top of this.

You can distinguish both when looking at the example in the middle of the picture below. The glare mostly consists of the two 'beams' radiating out to the bottom. If you cover those beams, you'll see that the rest simply rotates and moves with the jet. This is because the rest is something physical (hot exhaust gas), not glare.

What you see in the left picture is mostly hot gas, not glare.

Treating the whole gimbal blob as a glare of a jet exhaust seems a bit of a stretch to me.

#### Buckaroo

##### Member
Treating the whole gimbal blob as a glare of a jet exhaust seems a bit of a stretch to me.
Except that even in the clip you just posted, you can see by looking at the clouds that the gimbal motion coincides with the "rotation" of the object, demonstrating pretty conclusively that the rotation is an artifact of the mechanism itself, and is exactly the kind of artifact that is produced by glare. Unresolved blobs tend to look alike. This doesn't mean they're the same thing.

#### Itsme

##### Active Member
Except that even in the clip you just posted, you can see by looking at the clouds that the gimbal motion coincides with the "rotation" of the object, demonstrating pretty conclusively that the rotation is an artifact of the mechanism itself, and is exactly the kind of artifact that is produced by glare. Unresolved blobs tend to look alike. This doesn't mean they're the same thing.
Or it could be a coincidence. The object reacting when the jet points its nose at it which happens to coincide with the gimbal rotation. Is there a picture or movie clip indicating that both rotate to the same degree?

#### AmberRobot

##### Senior Member
Except that even in the clip you just posted, you can see by looking at the clouds that the gimbal motion coincides with the "rotation" of the object, demonstrating pretty conclusively that the rotation is an artifact of the mechanism itself, and is exactly the kind of artifact that is produced by glare. Unresolved blobs tend to look alike. This doesn't mean they're the same thing.
Also there are other features in the video that rotate at the same time. Adding these and that the rotation happens when the view angle goes through zero degrees suggests that Mick’s explanation is quite a probable one.

#### Domzh

##### Active Member
It does, though. What you're describing is not how scattering or diffraction in optical systems works. And the fact that Mick shows multiple examples of this very phenomenon, some from other FLIR systems, demonstrates this. See, e.g, 0:30 in his video:

you dont understand what i mean.

im not even arguing that the possibility of glare rotating independently from the source.

what i say is the object is centered in the footage. when the gimbal rotates, the glare stays perfectly centered over the object and in its relative position in space (against the horizon and clouds).

if the glare is caused, by something on the window (scratch, smudge, Underwoods underwear,...) then the distorted light / straylight wouldnt rotate on its center axis while keeping the same relative position.

it would cause an offset position or distortion.

this is undeniable if the cause for the glare / stray light happens because theres something on the window.

if the glare would happen INDEPENDENTLY on a perfectly smooth and clear window then I agree, i can see how the gimbal effect could have happened.

BUT IF WE SAY the cause for the glare / straylight is found on the window, than my statement is true.

do your own mick west glare experiment with a flashlight or sun. but dead center the glare hardware or software wise in your video. hold a window in front of your camera and smear it. then rotate while keeping the glare centered.

you will see the surroundings behave as I have described it, theres no clear rotation keeping its relative position.

the reason i bring this up is because of the interview mick had with a flir technician. who stated he has seen glare effects that rotate with the gimbal BUT ONLY when the window is smudged.

hence why i thought about how such a glare would behave, and it wouldnt behave as im the gimbal video

#### Buckaroo

##### Member
BUT IF WE SAY the cause for the glare / straylight is found on the window, than my statement is true.
You keep saying it's true. It isn't. Again: you can see the effect clearly demonstrated in Mick's video, in multiple different contexts.

#### Domzh

##### Active Member
Also there are other features in the video that rotate at the same time. Adding these and that the rotation happens when the view angle goes through zero degrees suggests that Mick’s explanation is quite a probable one.

my hypothesis is, because its infrared, its possible the source emitts IR radiation in all directions in the sky, when the source rotates the distribution / pattern rotates together with it because it is still emitting the same distribution of IR that is now rotating along with it.

@Mick West

#### Domzh

##### Active Member
You keep saying it's true. It isn't. Again: you can see the effect clearly demonstrated in Mick's video, in multiple different contexts.
he did not locked it to center though and looked how the surroundings behave in relative distance to its center point during the stabilized rotation. can keep referencing these videos for as long as you want, we are not talking about the same effect

you can even slightly see the effect i am talking about in his flashlight video. and here we arent even talking about a moving object in a big open space where the effect would be even more pronounced

#### Buckaroo

##### Member
you can even slightly see the effect i am talking about in his flashlight video. and here we arent even talking about a moving object in a big open space where the effect would be even more pronounced
I think I see the source of your error. You're talking about lens flare, not glare. They're two different processes. There isn't any appreciable lens flare in the GIMBAL video.

#### Domzh

##### Active Member
I think I see the source of your error. You're talking about lens flare, not glare. They're two different processes. There isn't any appreciable lens flare in the GIMBAL video.
no i am not talking about lense flare and possible artifacts. i am talking about distortion of glare.

i believe we should agree to disagree or shift our discussion to PM for the sake of this thread

#### Buckaroo

##### Member
no i am not talking about lense flare and possible artifacts. i am talking about distortion of glare.

i believe we should agree to disagree or shift our discussion to PM for the sake of this thread

Can you post an image or a video of a clear example of what you're talking about? It might be easier to understand that way.

I think what we're seeing IS a distortion of the glare - i.e. unless the pattern of optical imperfection is completely uniform within the 2D plane, there will be a distortion of the glare along a preferred axis, giving us a slightly elongated "saucer" shape. When the optical system rotates, this distortion axis rotates as well, producing the effect in the video.

#### Domzh

##### Active Member
Can you post an image or a video of a clear example of what you're talking about? It might be easier to understand that way.

I think what we're seeing IS a distortion of the glare - i.e. unless the pattern of optical imperfection is completely uniform within the 2D plane, there will be a distortion of the glare along a preferred axis, giving us a slightly elongated "saucer" shape. When the optical system rotates, this distortion axis rotates as well, producing the effect in the video.
youre almost there. now just imagine what will happen if the cause for the distortion isnt perfectly centered but at an offset position on the window. when this window rotates, the "distortion spot" will rotate around / across the real object and will alter its perception and most likely even position relative to it, while the real object would stay stationary.

#### AmberRobot

##### Senior Member
youre almost there. now just imagine what will happen if the cause for the distortion isnt perfectly centered but at an offset position on the window. when this window rotates, the "distortion spot" will rotate around / across the real object and will alter its perception and most likely even position relative to it, while the real object would stay stationary.
It depends on the size of the optical footprint of a resolution element at the axial position of the window. The window is not going to be in focus, so as the light from an external object passes through the window it can be modified by whatever defect happens to lie in that footprint. The size and shape of the point spread function will be modified. With a bright, unresolved and likely saturated source the PSF will dominate the shape that is seen on the camera’s focal plane. That’s why I was asking about the optical design because the magnitude of the effect depends on the relative location between the window and the entrance pupil to the camera.

I think you are picturing something more akin to viewing through a car windshield and seeing sunlight glint off a smudge or defect on the window. Then the light would appear to come from the direction of the defect, not the source. I’m not certain that is an appropriately comparable situation here.

#### JMartJr

##### Senior Member
when this window rotates, the "distortion spot" will rotate around / across the real object and will alter its perception and most likely even position relative to it, while the real object would stay stationary.
Hiya --
I'm trying to understand and struggling. Could you perhaps do w quick demonstration vid demonstrating what you are talking about? With 1 picture proverbially being worth a thousand words (and a video being thus worth several kilo-words a second) it might save some time and space. And it might help me to understand your point. Thanks!

#### Ravi

##### Senior Member.
Domzh said:
when this window rotates, the "distortion spot" will rotate around / across the real object and will alter its perception and most likely even position relative to it, while the real object would stay stationary.

Hiya said
I'm trying to understand and struggling. Could you perhaps do w quick demonstration vid demonstrating what you are talking about? With 1 picture proverbially being worth a thousand words (and a video being thus worth several kilo-words a second) it might save some time and space. And it might help me to understand your point. Thanks!
Thats is because it does not work that way. The window is not in the object plane and therefore the smudge on it does not get resolved in the image. So Domzh's idea is not seen. Both flare and smudge are straylight inducers though.

#### Domzh

##### Active Member
no not a car window.

imagine the upper half of the gimbal front section window would be smeared with butter, the lower half would be clear

we look at a jet with a glaring engine

if we look at the picture on screen, we would now see a plane where the upper part of its engine-glare would be distorted

if the pod rotates about 90 degrees now, the uncorrected image would show a plane on its side, while the glare wouldnt rotate together with it but now the (depends on rotation side) left side of the glare is distorted

if we now stabilize the picture (derotate it) to level the horizon, we would see a stable object and stable horizon, with a rotating glare that rotates through a distortion spot (if i visualize this correctly).

another example i believe could be if you take a camera, put an optic on it, and on this optic you place a contact lens. but not in the middle but on its edge.

not middle: ( o )
on its edge: (o )

if you would now film a flashlight-glare, and move the contact lens (simulating the rotation of the smudge on the window) it would distort it, correct?

is it me not delivering my point clear enough or am i totally not getting something?

(both could be possible, its hard to explain bc english isnt my main language)

#### Ravi

##### Senior Member.
no not a car window.

imagine the upper half of the gimbal front section window would be smeared with butter, the lower half would be clear

we look at a jet with a glaring engine

if we look at the picture on screen, we would now see a plane where the upper part of its engine-glare would be distorted

No, this is not what happens. Please read my former post (nr 586)

#### Domzh

##### Active Member
so when you say the smear on the window will not alter the glare perception in any way shape or form (if i understand you correctly) than you are contradicting the FLIR technician Mick interviewed and who told Mick he has seen these glare rotations BUT ONLY when the window was smudged.

#### Ravi

##### Senior Member.
so when you say the smear on the window will not alter the glare perception in any way shape or form (if i understand you correctly) than you are contradicting the FLIR technician Mick interviewed and who told Mick he has seen these glare rotations BUT ONLY when the window was smudged.

EDIT

Well, the glare will not be shown as a "cut in half" image. So that the upper half has glare, and the bottom part not. This is not correct, the glare is distributed over the entire image.

I made a small paraxial diagram of similar optical situation, attached below. As you can see, the window is not imaged. This means no localised window artefacts (your smudge) can be resolved.

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#### DavidB66

##### Senior Member
if the pod rotates about 90 degrees now, the uncorrected image would show a plane on its side, while the glare wouldnt rotate together with it but now the (depends on rotation side) left side of the glare is distorted

I haven't followed this discussion closely, but I think the passage I have quoted from #587 overlooks one important point. In Mick West's 'glare' hypothesis it is assumed [KEY ASSUMPTION] that the 'uncorrected' image is viewed in a display where the 'top' and 'bottom' of the screen correspond to the 'top' and bottom' of the camera, or in this case the ATFLIR pod. If the camera/pod rotates, the objects beyond the camera will rotate in the image on the screen, but anything that is fixed in relation to the camera, e.g. cross-hairs, or the hypothetical smear of butter, would not rotate in the image on the screen. Since it is the hypothetical smear that is responsible for what Domzh calls the 'distortion of the glare', the distortion would not rotate on the screen either: if the smear is at the top, the distortion will stay at the top. But if the system then derotates the entire image, to cancel out the unwanted rotation of the objects beyond the camera, anything that is fixed in relation to the camera (cross-hairs, smear, distortion of glare, etc) will rotate on the screen. Which is more-or-less what is seen in the Gimbal video.

Whether this is the correct explanation of what is seen depends in part on whether what I have marked as the KEY ASSUMPTION is correct. It seems very reasonable, but I don't know if it can be confirmed from the documents.

#### AmberRobot

##### Senior Member
I would also assume that the display is fixed orientation relative to the detector. However because there is a derotator (likely a “K-mirror”) then there is a set of optics fore of the derotator that are not fixed relative to the detector. If the scene is kept fixed on the detector then there will be a relative change in orientation of any effect caused by those optics.

#### Domzh

##### Active Member
@Ravi @DavidB66

so the glare happens on the window itself and not on the camera sensor? So the glare will rotate together with the window ON the window?

#### FatPhil

##### Senior Member.
yes i know my thoughts are solely regarding the flir technicians feedback that he:

1) has seen flare/ glare rotate
2) in order for it to happen the window cant be clear but "whiped clear" with a sleeve resulting in a smudge (according to him thats what pilots do)

so if we assume that this is correct, the glare claim becomes extremely unlikely compared to the actual gimbal footage (the why as stated above in my previous post).

Smearing from a sleeve and a thumb mark on a microscope slide will create the same optical effect - Mick's model holds.

You should also remember that "glare" is a gloss. Glare isn't a tangible thing in itself, it is the misperception of a thing by another thing, and as such happens in the detector. HDR techniques can mitigate against it. Pretty similar to "bloom" in its effects, as both are the bleeding of high signal into low signal areas. There's probably some bloom in these captured images, but given that the unsharp-like halos are a feature, they're probably being processed out. (Less closely related, but still with the same visual effect is "bleed", that's a sensor issue in the electronic domain rather than an optics issue.)

#### AmberRobot

##### Senior Member
@Ravi @DavidB66

so the glare happens on the window itself and not on the camera sensor
The glare happens because some light passing through the window along the line of sight toward an object can get deviated a little by the impacts of diffraction, geometric aberrations, or defects on the optics.

it is light from the source that is detected in the sensor at focal positions that extend beyond that of the source.

the question for me is how close the window is to a pupil plane because at a pupil plane a defect will impact all field angles the same (a la your camera’s iris). Otherwise it depends on how much of an object’s light passes through a particular area on the window.

#### Ravi

##### Senior Member.
@Ravi @DavidB66

so the glare happens on the window itself and not on the camera sensor
Correct. Straylight = glare. And a non perfect surface (perfect: polished to nm surface roughness) is causing the passing light rays to scatter, ruining the image causing noise and glares.

#### Itsme

##### Active Member
Except that even in the clip you just posted, you can see by looking at the clouds that the gimbal motion coincides with the "rotation" of the object, demonstrating pretty conclusively that the rotation is an artifact of the mechanism itself, and is exactly the kind of artifact that is produced by glare. Unresolved blobs tend to look alike. This doesn't mean they're the same thing.
This animated gif is the gist of it. If I cover the object I only see movement consistent with the jet's banking angle. The rest seems to be random noise, small variations in the background or maybe subtle lens flares that vary with the banking angle of the jet. I'm not convinced at all there is anything rotating in the background in sync with the object, only with the jet's banking angle. Sure, there are some bumps of the camera system but nobody claims these bumps are movements of the object itself.

To see this you have to cover the object, though. Otherwise your brain will trick you in seeing a correlation with the object instead of the jet's banking angle.

#### Domzh

##### Active Member
@Ravi i see! in this case i wasted a page of discussion and admit my idea was bs lol

so it doesnt matter what kind of mirrors or derotation happens behind the window, because nothing can distinguish the entering light anymore from these two sources ("real world" and "window") and therefore it gets merged into one new image, correct?

thanks for taking the time

#### fartchitect

##### New Member
Sorry to jump into the conversation, I'm new here. Apologies if I'm asking an obvious thing, but in Mick's rotating glare hypothesis, would an actual rotation of the glare's source have any influence on its perception on the camera sensor?

I'm trying to figure out if an actual rotation of the object would change the orientation of the glare. I'm asking this because I've observed a couple of "bumps" in the video that can be either from the dero mechanism or just turbulence, but they "shake" the frame in the same way and not all of them result in a rotation of the glare.

My understanding is that the glare is the result of light - subsurface scatter at small scale generated by surface imperfections (or smears) on the pod's frontal glass. So as long as the glare has some sharpenss (around the edges), I'm assuming the scattering effect on the glass does not distort the source's outline that much. So if the source rotates, you should see it on the screen, right?

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#### Buckaroo

##### Member
This animated gif is the gist of it. If I cover the object I only see movement consistent with the jet's banking angle. The rest seems to be random noise, small variations in the background or maybe subtle lens flares that vary with the banking angle of the jet. I'm not convinced at all there is anything rotating in the background in sync with the object, only with the jet's banking angle. Sure, there are some bumps of the camera system but nobody claims these bumps are movements of the object itself.

To see this you have to cover the object, though. Otherwise your brain will trick you in seeing a correlation with the object instead of the jet's banking angle.
No, there is indeed a correlation. The reason you're not seeing it is because the magnitude and direction of the apparent movement aren't the same as the apparent rotation of the image field window, which is to be expected in a mechanism that uses the compounded movement of multiple axes to correct the orientation. But the noise in the sky, in particular, is perfectly in sync with the apparent magnitude and direction of the rotation of the blob. You can even discern the preferential direction of the glare distortion within the noise.

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