FLIR Pathfindir II image gets darker when water drops on lens/in rain

[Dark Volter]

So, I recently acquired a Flir Pathfindir II, which i'd been after for a long time ever since seeing the OEM version on BMW's in 05.
(note: A few years ago I also acquired a Therm-App HZ)

(my setup)

I am in FL where it rains frequently.
And upon finally getting it installed , I have noticed a odd issue, that I was curious if anyone had experience with?

I noticed that, with rain droplets on the front lens, cause the image to get severely darker, and all I can see are hot tailpipes , the environment disappears completely in the image. I am surprised, as I assumed the camera would adjust it's lower temperature span like my Therm App thermal camera will do with the default app(or I can do it myself using the Therm-app Plus app), to bring things back into view. I cannot manually adjust the PF2 at all.

After nearly a month of using it, in various situations and comparing against my Therm-App HZ in rainy conditions(being a bit careful since the Therm-App isn't waterproof)  , I have confirmed the image  from the Pathfindir II does oddly get darker when water drops are on the front of the camera. I did bug FLIR tech support, and the person I talked to mentioned that the image adjusting like that should only happen if something very hot or cold gets in the image- I noted that I could , then drive my car so it aimed at a wall or bunch of trees where there were no sources of hot or lack of IR(cold) in the image and then take a picture of it still being dark,  and was sorta passed over/ignored on that suggestion.

From elsewhere on the web it was suggested that Autoliv codes the OEM version for the cars' algorithms, and then the PF2 is just a copy of that.
I find this odd, as I know they test this camera in cold weather, but in FL in the humid air when it's raining , the image shouldn't degrade..It does surprise me that water drops on the front make it adjust like that- and that hot sources of IR like tailpipes then can get through still.

The Pedestrian Detection/Animal Detection feature (which i do have),FLIR support mentioned would still work regardless , if i had it- and it does, but at slightly reduced range... for those who get the camera without the feature though, they'd only have a dark image...with tailpipes.

I am aware IR cannot go through actual water flow(which isn't this), - however, if this was my Therm-App HZ, I would take the bottom number of the temperature span and lower it until the environment comes back into view. I tested this actually today in the rain with the TAhz and sure enough, the image got a little darker(in Therm-App Plus), then I lowered the bottom of the span till the environment was back- that was easy.

I find this a shame, as these cameras have been long marketed as being able to see through obscurants- and research papers from FLIR themselves note the extent in bad weather where their cameras will still penetrate fogs and haze and rain. The cameras do have a heater, but that is for cold weather and presumably ice, I assume the heater would also take care of rain, but it's obviously not going to turn on in warm weather. I have not had the chance to test it in very cold weather with rain, and can't tell when the heater is on.(I have driven in cold air with it.)

I know SEEK just announced at CES  a $1000 auto thermal camera with the same specs as the PF2 they are working on- I  wonder if their algorithms will better handle this odd edge case.
You can't interface with the PF2 at all, but I know pretty much every other FLIR core lets you control settings on them- but none of them are IP69/waterproof, and the Boson- based driverless-car thermal camera vision project FLIR  have now is just underway(it would need weatherproofing)



Has anyone else encountered this issue?

(a few pictures of the effect)
https://imgur.com/a/dARzn

 

[Fraser]

Hi,

That is definitely abnormal behaviour from your Pathfinder.

The Autoliv version of the camera is protected against transfer out of the original car, it stops the camera even switching on. This is not the cause of your issue.

Have you taken a look at the front of your camera with your other thermal camera ? I am just wondering if your camera has a fault and the front window heater is running too hot so anything sitting on its surface reflects the significant heat back at the camera. The windows AR coating would enable the camera to see through the actual window but water would emit visible heat due to its decent Emissivity. I know you say the heater should only run in cold weather, but things can, and do go wrong  if this is the case, the camera would shift its centre temperature up and that is why you only see the hot exhausts. I would not expect the heater to run hot anyway as it is intended to prevent icing and not evaporate water per se.

You have not provided a history for your camera. It could sadly be a faulty unit that is in need of a visit to FLIR's service department.

I think the PFII may be very similar to the TAU core. If so, the configuration utility for the TAU may be able to access its setup and other useful information via an internal RS232 port. You would have to dismantle the camera though.

Fraser

[Fraser]

Another test you can do is to place a piece of shiny metal over the window. Such will act as a mirror for any heat generated by the camera and heated window. See if it causes a very bright image. You can also try placing a piece of card on the window (in direct contact with it) to see if the card starts emitting heat back at the camera. If the result is positive in these tests, it suggests something is wrong with the window temperature.

Fraser

[Fraser]

I just checked, the window heater automatically comes on at +4C and switches off at +6C. It is a 6W heater so you can see its behaviour by monitoring the cameras current draw. It should not be on above +6C and I would hope it is self regulating in terms of window temperature. It appears to directly monitor the window temperature rather than using the case or internal temperature. If it is not, there is a fault.

Fraser

[railrun]

Have you checked your Ge-window? Maybe it has a leak and water runs into your camera? https://www.audiworld.com/forums/a8-s8-d4-platform-discussion-190/replace-night-vision-assist-camera-2871957/#post24877036

[Fraser]

I had hoped we might hear more from the OP regarding this issue. It is always nice to hear of progress or a conclusion.

[Dark Volter]

Apologies- I actually haven't been able to get back because I ran into a hog shortly after - making a turn in a intersection

...and the PF2 is limited to a ~24 degree field of view, which of course will not see something to the side during an intersection turn....

the old Pathfinder 1 with it's wider...45 degree fov i think... I suspect that would nearly be enough for the situation i encountered...but  I have the next generation one...

/edge cases like very sharp turns..- it's why those companies at CES are pursuing options for driverless cars such as dual thermal cameras at angles to not just look ahead

The PF2 survived the hit, the front of my car did not fare as well- but I will take the first opportunity I get when all is settled, to look at it with my TA -HZ


I haven't been in 42 degree temp in over a month- and was due to travel north where it is this cold, but because of the incident, that is not happening now and i do not know when i will be in those temps again- Having said that, i've nothing that suggests the heater is turning on in the warm temps where i am..

I WAS able to find something with my therm app- i have been out in light drizzle a few more times, and a few times verified the image gets darker if drops get on the lens- using therm app plus, i was able to indeed counter this and return the image environment brightness to a proper one again..


I looked at that AUDI thread and am don't see errors like they are seeing- but then again, I have noticed the issue doesn't persist after heavy rain conditions stop......

I am looking into this further and plan to do some more things like adjusting my camera's angle a bit - it was pointed slightly high, and I wondered before if the algorithms need the ground in a good portion of the image rather than a small bit, to base the rest of the image off of. That probably will not totally eliminate what seems to be a algorithm issue, but I'm up for trying some things to get it to preserve effectiveness

[Fraser]

Very sorry to hear of your accident. I hope everything gets sorted for you soon.

Fraser

[Dark Volter]

So, I am following up on this old topic(I've lurked since them, I'm still around-apologies for the late response, as this is absolutely still 100% relevant )- as I finally just setup a second PF2 I had to buy, on my current car-


And so now i'm back to the situation i was before- it works perfectly except in the case when rain gets onto the front, where the image becomes darker,

in a similar manner to as if i took my Therm-App with Therm-App Plus and raised the number on the lower bound of the span until only the hottest things are still visible with darkness covering up everything else in the environment.


So, what options do I have?

I am going to toy again with putting a tiny piece of plastic wrap over the front of the camera but I suspect it's only going to slightly delay the water effect, not stop it or hold it off for a extended period of time -

I am starting to consider Germanium lenses like these
https://www.edmundoptics.com/f/germanium-ge-windows/13137/

- though i'd have to figure out how to mount something like this in front

(attaching a picture of my current install)from the front

[bap2703]

Isn't your problem just due to water sticking on the lens?
As it is opaque and cold you get the effect that your scene is wholy shifted to lesser signal values.
So the behaviour seems totally normal for a 'dumb' camera that doesn't adjust to the scene range.

Can you put the camera further back into the hood ?

[vdeny]

I know that you were able to play with settings on Pathfindir first generation but not on Pathfindir ii.
I also have it on my car and it pretty useless in rainy conditions for me too. Have you followed Seek? Did they made their version of thermal camera for cars at around $1000 price range?
Its also interesting to know how Flir manage this problem with their marine thermal cameras.

[Ultrapurple]

I don't know what it might do to optical coatings but I wonder if one of the hydrophobic coatings like those used on windscreens might be worth playing with? The one I know of that's available in the UK is called Rain-X and it is remarkable for the way it stops water wetting the glass.

My chemistry isn't good enough to know how it works or if it'd bond to anything other than glass, nor if it's even transparent to LWIR, but if someone's prepared to try potentially sacrificing a small germanium or ZnSe windor (perhaps a broken piece?) then the experiment might be worth a try.

If it works, rain simply won't hang around on the lens long enough for you to notice it!

Of course, you may be able to find a variant of this excellent idea to keep the lens clean and dry.

[meanie2]

Unsure if this would be helpful:

This guy used a piece of plastic as lens shield:
I used a clear protective photo sleeve to cut the lens shield out of. The plastic that the bag is made from is thermally transparent.
https://www.thingiverse. com/thing:1013936


There is a film called 'Xiaomi Guildford Car Mirror Anti Rain Film', not sure if you can use this as well.

[bap2703]

Vaguely related to this topic, this video might provide you some general information about thermal cameras in cars:

[Ultrapurple]

Thanks for finding that talk - it was very interesting and thought-provoking. I can see myself having wanted to race my friends along deserted roads in zero-visibility conditions when I was in my youth! Certain things would have mitigated against it though - where i grew up there were very few roads even as big as two lanes, my family wasn't loaded with money, the technology hadn't been invented yet and, perhaps most importantly, rural south-west England is not renowned for its sand storms 

[Dark Volter]

I am looking into what options might serve as a cheap , transparent window, rather than a 200 dollar window,



 

Vaguely related to this topic, this video might provide you some general information about thermal cameras in cars:

They talk about rain drips, but don't mention how they solved that problem of heat flashes- Though I dont think what i'm encountering is heat flashes, but rather the camera software not dealing with rain drops on the front at all- unfortunately


(also here at at 18:58 if others want to just jump to the porting on rain, you can't fast forwards on other links)

The software needs to be made with poor conditions able to be taken into account...as it's what will let a thermal cut right through it anyway, as I can demonstrate with my Therm-App HZ

I know that you were able to play with settings on Pathfindir first generation but not on Pathfindir ii.
I also have it on my car and it pretty useless in rainy conditions for me too. Have you followed Seek? Did they made their version of thermal camera for cars at around $1000 price range?
Its also interesting to know how Flir manage this problem with their marine thermal cameras.

That is a REALLY good question, and i'd love to know as well how FLIR's thermal cameras on their boats operate at all in rain or under heavy sea spray if they have similar software. I took a look at their boat FLIRS

and noted they seem to have something called flir detail enhancement
https://www.flir.com/products/m132/

Which makes me wonder if they got smarter, at a certain point and just refuse to update most of their cameras except the ones that had this from the beginning.


There's got to be a way to deal with this issue, lol - FLIR really should have tested their cameras in places like Florida, or whatnot- where rain is extremely frequent.

[Fraser]

FLIR’s comment on the matter......

https://www.flir.co.uk/support-center/oem/how-do-water-droplets-on-the-camera-lens-affect-the-image-do-they-affect-the-image-as-much-as-on-a-visible-light-range-camera/

It’s is just the physics of the situation.

Fraser

[Fraser]

More about the effects of fog and rain on thermal imaging camera range.....

https://www.flirmedia.com/MMC/CVS/Tech_Notes/TN_0001_EN.pdf

Fraser

[Fraser]

There is a lot of information on the internet regarding the effects of rain on thermal cameras. This is with good reason as thermal imaging is used for critical military and SAR operations. The technology is limited by basic physics, like all other technology. Understand it’s limitations, accept them and work within them 

https://oatao.univ-toulouse.fr/11729/1/Zenou_11729.pdf

Fraser

[Fraser]

http://www.securitysa.com/article.aspx?pklarticleid=5369


https://www.flir.co.uk/support-center/oem/does-the-pathfindir-ii-work-in-fog/

[Fraser]

Just to repeat what has likely already been said (TLDR) the presence of the water droplets on the lens does not normally cause a thermal camera to significantly darken its image. That sounds very much like some form of very aggressive ‘auto exposure’ algorithm at work. The setup of the Auto span and centre temperature algorithm is not something that is normally made available to the User of a TAU or similar imaging core. There are ‘auto exposure’ algorithms that are designed to deliberately highlight the warmest target in a scene, at the expense of background detail. These algorithms may be found in some fire fighting thermal cameras and weapon sights and are often heavily centre weighted. I do not know how FLIR configures your Pathfinder camera but it does appear that it is a little excessive in its response to rain droplets on the lens. Have you approached a FLIR and asked about this behaviour ? They may know exactly why the camera behaves in this way.

Fraser

[Dark Volter]

 

I know that you were able to play with settings on Pathfindir first generation but not on Pathfindir ii.
I also have it on my car and it pretty useless in rainy conditions for me too. Have you followed Seek? Did they made their version of thermal camera for cars at around $1000 price range?
Its also interesting to know how Flir manage this problem with their marine thermal cameras.

Oh, I have followed the others- it looks like there are multiple competitors, but only Hudway's thermal camera looks like it's about to come out
https://store.hudway.co/products/night-vision-camera-set.html
[I see very recently they just pushed this back from October of this year, and raised the price to 1500 from 1000, ]-they too were also targeting that price point...

- SEEK hasnt come out with their yet despite it being 2 years,
and ADASKY seems focused on automotive tech, unfortunately- i don't know if they'd come out with a system for people, or will just work on automated tie-ins for automated vehicles
(It also has not escaped my attention that they seem to also have no issues with rain- though of course I'd want to see more rain videos)




Nightride seems to already exist- a basic take, and a big form factor- but it's there, and at 900
https://nightride.io/

Seeing as everyone is trying to get that $1000 price point, and looking at how ADASKY's aiming to get slightly better sensors that seem to handle bad conditions far better than the Pathfindir II des- FLIR's monopoly days in this space ae in trouble(though they too are working on automated car vision as well, but with other cores of theirs)

[vdeny]

Hudway is not manufacturing and is not selling their own thermal camera. They are selling thermal camera that is selling on AliExpress or Alibaba. It costs around $1500-1700 for 1 camera.
Here is an example: https://m.alibaba.com/product/60826484205/vehicle-Infrared-Thermal-Imager-for-car.html?__detailProductImg=%2F%2Fs.alicdn.com%2F%40sc01%2Fkf%2FHTB1D4VdaiDxK1RjSsphq6zHrpXar%2Fvehicle-Infrared-Thermal-Imager-for-car-or.jpg_140x140xz.jpg

https://m.alibaba.com/product/62034931952/Advanced-portable-car-video-ir-camera.html?__detailProductImg=%2F%2Fs.alicdn.com%2F%40sc01%2Fkf%2FHTB1oLaJL5rpK1RjSZFhq6xSdXXal%2FAdvanced-portable-car-video-ir-camera-for.jpg_140x140xz.jpg