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Re: Of DAS, EOTS etc..

Unread postPosted: 20 Nov 2018, 08:25
by hornetfinn
Taog, like Dragon029 here said, imaging system needs to have enough information about the target to actually detect it. This requires it covers enough pixels in the detector to be detected with certain probability. Here are couple of good references to how it works:

https://www.flirmedia.com/MMC/CVS/Tech_ ... 002_EN.pdf
https://www.flir.com/globalassets/impor ... asheet.pdf

You may notice that 640x480 detector has roughly equal Field of View with 25 mm lens as 320x240 detector with 13 mm lens. However it can detect a vehicle 2.2 km away whereas 320x240 detector can do the same from 840 meters away. This is most likely because the 640x480 detector has slightly higher sensitivity. Human target exhibit similar behaviour.

Here are specs from Thales:
https://www.thalesgroup.com/sites/defau ... 071005.pdf
https://www.thalesgroup.com/sites/defau ... eet%20.pdf

Here 768x576 resolution Catherine-XP has 13.5 km detection range against tank and 1280x1024 Catherine-MP has 20 km detection range with narrow Field of View setting. This despite the fact that Catherine-XP has slightly higher sensitivity and narrower Field of View (higher zoom).

As you can see from these examples, higher resolution yields longer detection range against all target types. Sure sensitivity will affect range also, but only against some targets with very low thermal signature. Most targets will have high enough signature to be more affected by the resolution than sensitivity with modern systems.

Here is another document which has some additional info:
http://www.drsinfrared.com/Portals/0/do ... 0-683A.pdf

Re: Of DAS, EOTS etc..

Unread postPosted: 14 Mar 2019, 06:57
by marauder2048
Hadn't seen this before but we talked about FPAs as a driver for fibre channel data rates.

https://www.itea.org/wp-content/uploads/2018/12/MOLLOY-Zap.pdf

Re: Of DAS, EOTS etc..

Unread postPosted: 17 Sep 2019, 15:04
by taog
Image quality and resolution difference between EOTS and Advanced EOTS

https://news.lockheedmartin.com/2019-09 ... evelopment

Image

Re: Of DAS, EOTS etc..

Unread postPosted: 17 Sep 2019, 15:30
by sprstdlyscottsmn
Assuming the range is the same, that is a much clearer picture

Re: Of DAS, EOTS etc..

Unread postPosted: 17 Sep 2019, 17:02
by doge
:shock: It looks pretty clear. :applause: I expect the detection effect improve of enemy fighter's frontal in the air. 8) (more longer)

Re: Of DAS, EOTS etc..

Unread postPosted: 17 Sep 2019, 18:29
by playloud
Not sure that is apples to apples. Looks to be a different wavelength?

Re: Of DAS, EOTS etc..

Unread postPosted: 17 Sep 2019, 20:04
by spazsinbad
ScreenGrab in greyscale from Video.

Re: Of DAS, EOTS etc..

Unread postPosted: 18 Sep 2019, 08:38
by hornetfinn
playloud wrote:Not sure that is apples to apples. Looks to be a different wavelength?


Difficult to say from that image and video. Advanced EOTS images could be SWIR or they could be MWIR image from larger aperture, higher resolution and better thermal sensitivity. It might well be that they are showcasing the SWIR capability with that image. To me it seems like there are shadows in that image which would mean SWIR (or NIR) as MWIR (or LWIR) images don't have shadows.

I think it's good comparison as it shows how much the image quality is improved. With Advanced EOTS there is possibility of using SWIR or NIR for targeting which gives advantages especially in complex urban environment. Of course MWIR would be used in both in cases where there is too little light available for SWIR/NIR detector. Even then the Advanced EOTS should have higher performance, although the difference might not be huge in practice as EOTS itself has pretty good MWIR detector already.

Re: Of DAS, EOTS etc..

Unread postPosted: 18 Sep 2019, 12:34
by Dragon029
One cue that they're different spectrums is that the face of the building just below the roof is white in the EOTS' MWIR image but black in the AEOTS image, despite the glass being dark in both images (which would signify they're both on white = hot).

There also appears to be sky visible in the top-right corner of each image, with that being dark in the EOTS and bright in the AEOTS shot, suggesting that it's an SWIR / NIR sensor (although to play devil's advocate, if there were clouds covering that portion of the sky they might appear bright in MWIR).

Re: Of DAS, EOTS etc..

Unread postPosted: 18 Sep 2019, 13:24
by ricnunes
Isn't it possible that the image from the right is generated by combining the MWIR and SWIR imagery together an shown to the pilot as a single imagery?

This wouldn't be the first time that something similar would be done. For example the M-TADS (Arrowhead) which equips the latest version of the Apache attack helicopter (AH-64E Apache Guarding) is already able to combine IR with TV imagery and show it to the pilot as a single imagery:
https://www.defenseindustrydaily.com/ar ... tem-06461/

Arrowhead also has an image-intensified TV camera to aid aircraft pilotage in thermal environments and urban scenarios. The TV camera enables the pilots to see ground tracers, laser points and other signals from the ground. The system’s software combines imagery from the TV and the FLIR sensor into one multi-spectral image for the pilot and crew.


So if you can merge TV with IR then merging MWIR with SWIR should also be possible, right?

Re: Of DAS, EOTS etc..

Unread postPosted: 18 Sep 2019, 13:54
by Dragon029
It's definitely possible to combine them, but in all attempts of fusing different spectral images in video I've seen so far, it's been evident from minor artifacts in how one wavelength gets affected differently by things like heatwave refraction (or more commonly, differences in sensor resolution or framerate). Plus some aspects of blending MWIR and SWIR would be undesirable, such as the sky and any heat signatures in the sky both becoming more grey.

Re: Of DAS, EOTS etc..

Unread postPosted: 18 Sep 2019, 14:11
by hornetfinn
ricnunes wrote:So if you can merge TV with IR then merging MWIR with SWIR should also be possible, right?


Sure that would be possible and would definitely give advantages over having either one alone. That could be possible explanation too.

Re: Of DAS, EOTS etc..

Unread postPosted: 18 Sep 2019, 15:20
by quicksilver
Same day? Same time of day? Same atmospherics/environmentals? Same form/fit/power/cooling? Same OML? Lotsa questions before anyone ‘buys’ the improvement.

Re: Of DAS, EOTS etc..

Unread postPosted: 18 Sep 2019, 22:39
by ricnunes
quicksilver wrote:Same day? Same time of day? Same atmospherics/environmentals? Same form/fit/power/cooling? Same OML? Lotsa questions before anyone ‘buys’ the improvement.


Even if the time of day, atmospherics, etc... were different, it's clear that the right image (AEOTS) has a much sharper and higher quality imagery compared to the left (EOTS) which by its turn means better target VID.

Re: Of DAS, EOTS etc..

Unread postPosted: 18 Sep 2019, 22:53
by ricnunes
Dragon029 wrote:It's definitely possible to combine them, but in all attempts of fusing different spectral images in video I've seen so far, it's been evident from minor artifacts in how one wavelength gets affected differently by things like heatwave refraction (or more commonly, differences in sensor resolution or framerate). Plus some aspects of blending MWIR and SWIR would be undesirable, such as the sky and any heat signatures in the sky both becoming more grey.


Yes, I imagine that fusing different spectral images in video may bring some undesirable effects/artifacts in some/many of the systems made so far but this could be due to the following:
1- The inicial deployment of the first gen equipment using a new technology (this case multi-spectral imagery fusion) usually comes "filled" with "bugs". As technology progresses/evolves such bugs eventually get solved or "ironed out".
2- I would say that merging/fusing MWIR with SWIR is not exactly the same as "fusing different spectral images" since both MWIR and SWIR belongs to the same spectral wavelength, which in this case is IR (Infra-Red). Now fusing TV with IR imagery is indeed fusing different spectral images since TV uses to the Light spectral wavelength while IR like the name says uses IR spectral wavelength.
My point and 2 cents, is that in theory it could actually be easier to merge MWIR with SWIR compared to merge TV/Light with any IR imagery, and even more so considering the impressive and unique sensor fusion capability of the F-35.