DIY-Thermocam: A low-cost thermal imager based on the FLIR Lepton sensor

by rittermax • 3 years ago

170 92 3 years ago

rittermax11• 3 years ago

The DIY-Thermocam V3 is a low-cost, do-it-yourself thermal imager, based on the popular radiometric FLIR Lepton sensor and an open-source ecosystem.

It gives private persons, educational institutes and companies access to a portable, affordable and customizable thermal imaging platform that is based on open-source software and hardware. It is constructed as a self-assembly solution, that can be build at home by only using some standard tools.

There are various applications like finding heat leaks in the insulation of buildings, the analysis of electrical or mechanical components, the detection of persons / animals or even mounting it on a drone and recording continuous or time-lapse images.

The device has a large ecosystem of software around it, that allows to extend the functionalities of the device beyond the firmware itself. You can use the Thermal Analysis Software to edit raw data files on your PC and save them in various file formats. In addition to that, the Thermal Live Viewer can stream live thermal images to your PC, change settings on the fly and record images or videos. The Thermal Data Viewer provides another way of editing raw files, and with the Video Converter you can convert series of captures images to movie files.

The Device Firmware provides a lot of functionalities, that can be accessed over the 3.2" TFT LCD touch screen. Flashing the firmware is easy and can be done without any programming knowledge on any operating system over the command line interface. Once the Thermocam is connected to the PC, it will show up as a mass storage device and allows you to transfer thermal images from or to the device.

The DIY-Thermocam offers a wide range of features, like adding temperature points, changing temperature range limits, displaying hot or cold temperatures only, saving single images or a series of images (video or timelapse) to the integrated storage, changing the color scheme, etc. It can also communicate to the PC over the USB serial protocol, in order to stream thermal images or change settings remotely.

In case you want to extend the existing featureset with your own functionality, that's possible too. The firmware of the DIY-Thermocam is completely open-source and written in C/C++. Just download Visual Studio Code and the PlatformIO extension, and you are ready to go!

sitkack6• 3 years ago

Your parts list is missing the actual Lepton imager, https://www.diy-thermocam.net/docs/partlist/ I know it is on the other group gets page. I was not able to find the BOM in the GH repo. This would be a useful addition.

It looks like in an earlier version you had a visible camera as well, what was the choice in removing it?

I take it the device does not present itself as a web cam?

rittermax11• 3 years ago

Thanks for mentioning the missing parts. It was so obvious that I missed it, they are now added ;)

You are right, Version 2 had a visual camera. However, the alignment between LWIR sensor and visual camera was never perfect and most people only used the thermal image feature OR they took photos with a smartphone and combined it in the Thermal Analysis Software (ThermoVision) on the PC later on. That's why I decided to remove the visual camera for V3 to reduce building complexity and costs.

pwg2• 3 years ago

The very first line of the "Building" page states:

The DIY-Thermocam V3 Kit from GroupGets contains all required parts to build the device:

One has to scroll below the image to see a suggestion that the FLIR sensor and breakout board are not included in the kit.

The groupgets page is more clear, but even there one has to scroll to very far down before one finds:

The DIY-Thermocam V3 self-assembly KIT contains all required components excluding the FLIR Lepton 2.5/3.5 and the Lepton Breakout Board V2.

When I started reading the "Building" page, my interpretation of "all required parts to build the device" is that all (meaning every last one) parts necessary are contained in the kit. Finding the wording just after the large photo of "in case you do not already have ..." seemed odd, as it was hinting at "all" not really meaning "all", but not making such meaning clear. Only the groupgets page clarified that "all" did not in fact mean all, and even then took some scrolling to find that clarification.

I suggest you reword the first sentence of the "Building" page to read:

The DIY-Thermocam V3 Kit from GroupGets contains all required parts excluding the FLIR Lepton 2.5/3.5 and the Lepton Breakout Board V2 to build the device:

rittermax11• 3 years ago

Thanks for the feedback, it was indeed missleading to write it like that. I have improved the text as you have proposed it, so it is much clearer now what is required :)

splitbrain• 3 years ago

Awesome project. But $300 is still quite steep for a thing I might maybe use once a year. I really wish these thermal sensors came down in price...

doctorwho42• 3 years ago

I don't know if it's been awhile since you looked, but prices have dropped if you don't look at the name brand:

Bought one of these for work (HIKmicro, 160x120/19200pixel) for ~$300. It works, it's quite good compared to any thermal camera I played with 5+ years ago (even the fancy ones).

https://www.amazon.com/HIKMICRO-Resolution-Portable-4%C2%B0F...

It's important to note that camera sensor tech has been advancing quite rapidly these past two decades.

sitkack6• 3 years ago

The sensor itself is 160. There is no getting around that.

kragen5• 3 years ago

you could make your own thermal sensor, which is what i thought the article was going to be about from the title

this is a bit like 'i made a working, drivable car from scratch using only basic hand tools, raw materials, and a 2005 honda civic' or 'i built my own operating system around the linux kernel'

01100011• 3 years ago

You can rent a FLIR camera for $80/day from Home Depot if you really need one for a quick project.

schappim• 3 years ago

I would not call a FLIR Lepton affordable for everyone.

dpflan• 3 years ago

Do you know of a good, lower-price substitute?

sitkack6• 3 years ago

You can get MLX90640 based devices for under $50, but the resolution is 32x24 instead of 160x120

https://www.melexis.com/en/product/MLX90640/Far-Infrared-The...

rasz2• 3 years ago

$300 160x120 @ 9fps FLIR Lepton, and its a DIY kit. Hilarious. Meanwhile INFIRAY P2 Pro/T2S+, SNDWAY SW-8256 is a ~$200 _25hz_ 256×192.

rittermax11• 3 years ago

Indeed, smartphone addons are much cheaper and might be a good option, too!

nibbleshifter• 3 years ago

Lepton sensors cucked because itar lol

rtomanek• 3 years ago

$523 total? That's not my definition of affordable.

atoav• 3 years ago

Depends. 523 USD for a car is suspicously cheap. 523 USD for a mediocre sandwich is outrageously expensive.

Context matters and thermal imaging is very expensive usually.

hansvm• 3 years ago

Separately, there's a notion of purchases large enough you have to plan for them. $523 is a few weeks of pay for some people even in the US. The headline is set up to suggest a low-cost (because it's DIY) relative to the status quo of devices an average student couldn't really buy to tinker with. The result is more expensive than an off-the-shelf thermal camera I bought awhile ago without substantially better features (other than tinkerability).

Goz3rr3• 3 years ago

I still find it expensive for a thermal imager. I personally bought a Chinese Guide PC210 for €216 shipped, and that includes 21% VAT, for a whole unit and not just a sensor. For another €15 I got a ZnSe lens for macro use.

Not only is it cheaper, on paper it's also much better:

  - 45 mK vs 50 mK thermal sensitivity  
  - ±2 °C or ±2% vs ±10°C or ±10% accuracy  
  - 256x192 vs 160x120 resolution  
  - 25 vs 8.7Hz framerate  
  - -20 to 550 °C vs -10 to 450 °C range

The kicker is that (being European) I can't even get a FLIR equivalent to some of these specs, as they would violate ITAR export restrictions.

rittermax11• 3 years ago

You are right, there are cheaper solutions like smartphone addons, but as a standalone thermal imager including display, storage, etc., there are not many options that are less expensive and provide the same flexibility in terms of open-source software and hardware. This is a comparable all-in-one device from FLIR itself: https://www.amazon.de/FLIR-89401-0202-C5-Kompakt-W%C3%A4rmeb...

OJFord• 3 years ago

Can you make a slightly crappier version with a much cheaper visible spectrum sensor? I don't know much (obviously) about how they work, but intuitively it would seem a bit weird to me if they just happened to be restricted to exactly the same part of the spectrum as our eyes as a hardware limitation. Can you ignore data about visible red and higher in firmware, and get a thermal image that's obviously not as good as a purpose-built sensor, but maybe useful for some applications?

ZiiS• 3 years ago

Yes standard sensors have a IR filter that can usually be removed. Raspberry PI sell thier camera without the filter as removal is tricky. However this is only very near IR nothing close to the capabilities of this.

kragen5• 3 years ago

prolly not for room temperature; planck's law tells us there's a rapid exponential dropoff of spectral radiance with f/T, and room temperature is about a third of the draper-point temperature, so you'd expect undetectably low radiance below about 2000 nm, three times the 700-nm limit of visible light

silicon's bandgap of 1.1 electron volts corresponds to about a 1100-nm wavelength; is that the minimum photon energy a cmos sensor can detect?

if i did this calculation right, the spectral radiance at 1100nm should be a couple million times dimmer than the 700nm radiance at the draper point

        You have: h c / boltzmann 700 nm 300 K
        You want:
                Definition: 68.513185
        You have: h c / boltzmann 2000 nm 300 K
        You want:
                Definition: 23.979615
        You have: h c / boltzmann 700 nm tempC(525)
        You want:
                Definition: 25.751996
        You have: h c / boltzmann 1100 nm 300 K
        You want:
                Definition: 43.599299
        You have: exp(43.6-25.8)
        You want:
                Definition: 53757836

11³/7³ is about 4 and 54/4 is 'a couple' to me

so it's not literally impossible to detect but it seems like you would probably need special conditions like a light-tight darkroom or a thermal emitter switching on and off at a particular known frequency for millions of cycles

blincoln• 3 years ago

Yes. In my experience, the scenarios where NIR picks up a difference due to heat are very limited. Years ago, I did a test and there was no visible difference with an electric stovetop until it was set to medium[1], which would be more than enough to severely burn your skin.

A physicist once emailed me to say that it's possible to pick up NIR emissions from a soldering iron, but only in a dark room.

Beyond the sensor limitations, MWIR and LWIR require special optics, because regular glass is opaque to them. The last time I looked into it, the glass was usually germanium-based.

One can do some neat stuff with actual thermal imaging. I was lucky enough to get a FLIR E4 when they could have the firmware replaced to turn them into an E8. 320x240 resolution is still pretty low, but having seen the difference between that and the stock 160x120, I'd not want to use a sensor with a resolution any lower than 320x240 or so.

[1] Scroll way down to the "Stovetop Bokeh (Stove on Medium-High)" section of https://www.beneaththewaves.net/Photography/Thermal_versus_N...

detaro2• 3 years ago

but intuitively it would seem a bit weird to me if they just happened to be restricted to exactly the same part of the spectrum as our eyes as a hardware limitation

being restricted to ~visible spectrum is a design goal for a camera, since we expect it to produce images that look like what we see. Your usual camera sensor will see a bit further into infrared than humans do (hence why cameras usually contain a filter filtering that out), but not so far that it is in any way useful for things that aren't burning hot. E.g. with cheap digital cameras with bad filters you might see the coals of campfire being slightly tinted wrong, because those get hot enough to be visible, but everything else is not affected, and you'd think a camera was bad if it were

RobotToaster• 3 years ago

If you remove the infrared blocking filter (hot mirror) from many digital cameras, they can see very shortwave near infra red. Forward looking infrared (FLIR)[0] cameras detect long wave infrared, which is what you need for a "thermal" camera.

[0] quite what is "forward looking" about them I don't know

lawrenceduk• 3 years ago

I think the company originally made forward looking infrared sensors for military aircraft.

The name’s just stuck around since.

13of40• 3 years ago

"forward looking"

Old sensors worked like side-scanning sonar, where the image is built up one row at a time as your vehicle moves forward. Forward looking means you can just point it somewhere and take a 2D picture.

analog31• 3 years ago

Not strictly impossible, but probably difficult to the point where the FLIR sensor becomes a cheaper solution.

The visible detectors are kind of a lucky accident, that the visible spectrum is within the range that can be detected by a silicon sensor. Therefore, visible sensors are cheap and easy to make thanks to silicon IC technology. Sensors that detect IR beyond about 1 micron wavelength (the bandgap of silicon, where it becomes transparent) have to be made out of more "exotic" materials that are also more expensive. The problem might be surmountable, but fewer people want to set up and optimize "fabs" for those materials.

The problem with detecting heat with silicon is that the intensity is extremely low, and the amount of background radiation high. Getting a temperature measurement that isn't corrupted by other effects is going to be difficult.

lm28469• 3 years ago

Even modified sensors (removal of the IR sensor filter) barely see above 1000nm, which not anywhere close to what you need for thermal imaging

it would seem a bit weird to me if they just happened to be restricted to exactly the same part of the spectrum as our eyes as a hardware limitation.

That's a feature, for the leica m8 sensor "sees" UV and IR, as a result you need to use a UV/IR filter on your lens otherwise you get weird colors and blurrier images (since UV/visible light/IR all focus at different plans)

https://www.35mmc.com/14/02/2016/leica-m8-infrared-cut-filte...

Entinel• 3 years ago

For the people saying "this isn't affordable," decent thermal cameras range in the thousands of dollars.

DoingIsLearning2• 3 years ago

It still isn't affordable. You can get a phone add-on from FLIR for $180/$200.

This is a great exercise in building stuff for yourself but not affordable at all.

The thousand of dollars cameras you refer to have very high resolutions which are really not the use case for the curious maker that would be interested in such a project.

rittermax11• 3 years ago

The DIY-Thermocam also works with the FLIR Lepton2.5, which is slightly cheaper (but has a lower resolution): https://store.groupgets.com/products/flir-lepton-2-5

But I agree that the price might be too steep for the curious maker who does not have a serious use-case that satisfies the investment on the long run

baldeagle• 3 years ago

I’ve played around with the FLIR lepton a good bit and it can be pretty cool. I think the best current hackable platform is the Tcam. It is about an ESP32 combined with a Lepton. Great if you can use the iPhone app or setup a server to interact with it.

https://store.groupgets.com/products/tcam-mini-rev4-wireless...

rittermax11• 3 years ago

The tCam-Mini is also an awesome project, thanks for mentioning!

detrites• 3 years ago

Was curious and found this (somehow both terrible and amazing) video, of various everyday human activities, viewed through a good high resolution thermal camera: https://youtube.com/watch?v=48bwQVa0AQc

(Note, there are a couple of moments that are very NSFW.)

angry_octet4• 3 years ago

Cool video, but yes, I could have done without LWIR penis. Imagine the chaos this would cause an innocent physics teacher who showed this to a class of 15 year olds...

runjake• 3 years ago

If they don’t review the video for its educational value beforehand, and they somehow get past their District’s Restricted Mode filtering and they don’t notice the video being rated mature, the very first second of the film should give them a clue.

Also, this video is 8 years old now.

oneplane2• 3 years ago

It's pretty cool. But note that from an end-user perspective you're getting a Flir Lepton 3.5 thermal camera for $522.99. A Flir TG165-X does mostly the same stuff for a much lower price (and half the horizontal and vertical resolution due to the lower end lepton). But the TG doesn't allow you to hack it, and this project does.

A Flir ONE (2nd Gen) does almost the same, for about half the price. But again, not as hackable.

So while a bunch of people here might suggest that the price is very high, or the capabilities can easily be matched, it's a bit of a mixed bag. If you just want to see some thermal images, and you already have a smartphone, a Flir ONE might be for you. If you need a dedicated ruggedised hand-held cameras, get one of the ones from Flir. Anything beyond that is probably either too expensive or not as easy to integrate with what you need, and that's where this DIY comes in; easy to do whatever you want to, and good enough to outperform whatever else is on the market, but it will still cost money.

Edit: There is a PURETHERMAL-M which apparently is a USB interface board for the lepton module, so if someone wanted to hack around with a slightly less useful kit, but for a lower price, that's an option too. It does require a host system to control it, so it's not like you can use it as a 'handheld' like this DIY project.

rittermax11• 3 years ago

Agree. I think it depends on the use-case (and a personal interest in open-source and DIY stuff) which solution is the best.

For example with the open serial protocol of the DIY-Thermocam, you can build your own software applications in Python, Typescript, etc. to cover use-cases that are not part of any standalone solution (https://www.diy-thermocam.net/docs/serial/).

And if you are familiar with Arduino microcontrollers, you can change the firmware as you wish and extend it with new capabilities as well (https://github.com/maxritter/diy-thermocam/tree/master/firmw...).

oneplane2• 3 years ago

I think that it is where this project shines; the accessibility. After building and setting it up it can work stand-alone, but also integrated with any project you are already familiar with (within reason).

rasz2• 3 years ago

not matched, beat by Chinese $200 256×192@25hz USB modules https://www.youtube.com/watch?v=YMQeXq1ujn0

rittermax11• 3 years ago

I know that affordable is a flexible term and the DIY-Thermocam might still be too expensive for some folks.

The predecessor of this device was called "Cheap-Thermocam" (https://web.archive.org/web/20121128040746/http://www.cheap-...) and it used a single-spot MLX90614 sensor to create a thermal image by combining the measurements.

Although the project is now 10 years old, there is a good writeup if anybody wants to build it: https://www.instructables.com/Thermal-Camera/

angry_octet4• 3 years ago

Can anyone explain why I would get a FLIR Lepton system (America) vs an InfiRay P2 (China) system? The InfiRay seems to have much better performance for the price, and sturdier construction. But software? As much fun as DIY is, I want something with a UVC interface I can plug into a Linux machine.

coolhand2120• 3 years ago

I purchased an InfiRay P2 and it started failing the day after I purchased it. Had to return it. I suspect the seller just resold the defective unit over and over. Nice device if you can find a working one.

angry_octet4• 3 years ago

Was that from eBay/AliExpress etc or a proper retailer? If it was a retailer with a relationship to the manufacturer that indicates poor quality control on production stock. (E.g. I would hope these guys are okay: https://www.pergear.com/products/infiray-p2-pro )

joshvm2• 3 years ago

If you want a UVC setup then the purethermal carrier is the route to go.

You buy FLIR because they're well made, reliable products. Same reason people spend the money on Fluke. I'm not sure you can necessarily say the support is better for consumers because they mostly cater to OEMs, but the camera cores are (mostly) very well documented and software support is good.

giantg27• 3 years ago

"the camera cores are (mostly) very well documented and software support is good."

I have seen some good documents, but they are mostly tailored to OEMs as well. It also depends on what you want to do. I've been trying to get a lepton streaming video to a TFT screen using an ESP32. Resources are scares. If you hit a problem, you're basically on your own.

klondike_• 3 years ago

FLIR systems are limited in resolution and frame rate because of ITAR restrictions, even though they're the industry leader. Chinese systems have improved a lot in recent years and are not subject to ITAR and can offer higher resolutions and framerates

giantg27• 3 years ago

FLIR offers higher resolution and higher framerate options too. For that, they want you to buy a Boson or higher. They even make Leptons with 25fps capability. The firmware for the standard Lepton simply reads every third frame.

erwincoumans• 3 years ago

Strongly suggest looking into Guide T120 PC210 (resolution 256x192) see this eevblog review: https://www.eevblog.com/forum/thermal-imaging/guide-pc210-re... It can save JPG with temperature info, and also stream video to PC. I got it last year from AliExpress for around 299-350 USD and prefer it over the more expensive FLIR TG267.

yftsui• 3 years ago

UTi260B is also a good option, price swing between $260-$360 depending on time.

wkat42422• 3 years ago

"Low cost" is still 300 bucks. That's very expensive.

I wish this tech would come down a bit so it would enable a whole new range of applications that weren't possible before due to the price.

detaro2• 3 years ago

It's also lowish-cost for the field and is possible because the tech has come down quite a bit, which enabled a whole new range of applications that weren't possible before due to price. ;)

But I assume the chinese parts at least will continue to become cheaper, although afaik they are currently not as available as individual parts vs complete devices.

wkat42422• 3 years ago

It's been around this price for around 5 years at least, or more. Since the FLIR one came out really.

poulpy123• 3 years ago

+220$ for the sensor and breakout board. However looking at AliExpress the price looks reasonable

anigbrowl2• 3 years ago

Excellent specs and design, good value.

Somewhat off-topic, but if you want to get into thermal imaging for super cheap (albeit at a lower resolution again), you can get a compact FLIR kit from M5stack for $79 that's ready to use as soon as you charge it, but also freely hackable.

https://shop.m5stack.com/collections/m5stack-new-arrival/pro...

rittermax11• 3 years ago

Thanks a lot! That's super cool, very nice price tag, compact design, thanks for bringing it up :)

hgomersall• 3 years ago

It's really low resolution, but I wonder what could be done with some super resolution techniques. Is the transfer function of these sensors well defined?

anigbrowl2• 3 years ago

I don't know enough about thermal sensors to say with confidence and haven't looked up the spec sheet on this one at all. I'm just a fan of this manufacturer help them out with translation/documentation stuff occasionally. They market to prototypers and industrial clients and my experience is that their QA is good and they prioritize quality over lowest price.

adolph2• 3 years ago

MLX90640-BAA is an interesting sensor.

Adafruit’s breakout sounds interesting, like enough for a homemade AIM9

This sensor contains a 24x32 array of IR thermal sensors. When connected to your microcontroller (or Raspberry Pi) it will return an array of 768 individual infrared temperature readings over I2C. . . . This version has a wide 110°x70° field of view we also have a version with a narrower 55°x35° field of view. . . This version has a wide 110°x70° field of view we also have a version with a narrower 55°x35° field of view

https://www.adafruit.com/product/4469?gclid=Cj0KCQjwmN2iBhCr...

Early AIM9 explained: https://medium.com/@OpenSeason/1946-germany-has-been-defeate...

giantg27• 3 years ago

I've been working on a lepton project for about 5 months. The resources for examples and debugging are scarce and I don't have a lot of time to spend on it. It should be much cheaper than this using an ESP32. I haven't gotten it to work though.

I did get it working (but choppy) on a Pi Zero. I might be able to get it working smoothly if I wanted to trim down some of the other processes and prioritize this one. But the ESP32 should have faster start up.

I guess what I'm saying is be prepared for headaches if you want a truly DIY or really cheap lepton project.

adolph2• 3 years ago

Was your software running bare metal or with an OS?

giantg27• 3 years ago

On the Pi? I had an OS. I think it was the standard raspberry pi OS. I wanted to do Arch Linux Arm for the supposedly lighter xfce, but I couldn't find it. I'm way to dumb to do it bare metal all by myself.

spdustin• 3 years ago

Somewhat related: FLIR sold a handheld model back in 2013—the E4—that had the same electronics and sensors as their high-end E8 model. The E4’s firmware was originally unencrypted, so some enterprising folks quickly figured out how to turn the 80x60 E4 (~$1000) into a 320x240 E8 (~$6000). As in, functionality, resolution, and performance were indistinguishable between a modded E4 and a retail E8. They didn’t even bin the larger sensors, they literally just used flags to determine the capabilities that would be exposed to the end user. I still have that camera. :) Hackaday article from that time: https://hackaday.com/2013/11/04/manufacturer-crippled-flir-e...

ericpauley• 3 years ago

Not nearly as cool, but rigol’s 1xx4 series had similar bypassable firmware restrictions. For a broke college student being able to get a 100mhz 4-channel scope (the class equipment was only 2 channel) for a few hundred bucks really simplified a lot of labs. I suspect the firmware protections were purposefully weak knowing it would gain cred with budding EEs.

StrangeDoctor• 3 years ago

I was able to do the same thing in 2023 with a new retail E4.

reaperman• 3 years ago

I’m curious if this still the most cost-effective option for most hobbyists, 10 years later. If so, wow. Impressive that FLIR had a >10-year lead that persists through today.

9edda054-232f• 3 years ago

I would buy it if it's $50. $300 for a teensy 4.1? HELL NO.

fest• 3 years ago

There's another path to cheap thermal imaging- some premium cars have had thermal imagers for night vision (animal, pedestrian detection) for ~10 years.

The most common such system is Autoliv NV3, which is using the same sensor as Tau2/Flir E4/E8 (~320x256px). The original processing electronics does have protection preventing the use of it without car's ECU (though it's already broke), but the sensor interface is reverse engineered. Due to the age of the vehicles and the fact that the protective window in front of the lens is easily damaged, the modules can be bought relatively cheaply (I got mine for ~150EUR).

I made a breakout board for the sensor and have a more-or-less working nmigen gateware (using glasgow): https://github.com/festlv/isc0901b0-breakout

I don't have it fully working yet, as the sensor requires bias values to be sent for each pixel and Glasgow didn't have enough on-board memory to store them, and the thermal image without correct bias values is more or less unusable (many pixels are underexposed/overexposed).

I have hardware ready for ECP5 development board with enough onboard RAM but life got in the way, so it's still sitting in the pile of unfinished projects :/

There's also next generation (Autoliv NV4 == Veoneer NiVi4) which is based on 640x512 Boson sensor, though there is a lot less information about it.

vanillax• 3 years ago

Raspberry Pi equivalent https://petapixel.com/2021/03/25/how-to-build-your-own-therm...

doubleg72• 3 years ago

I built one of these in like 2015 when he first released the plans for the original. I recently put a Lepton 3.5 in it. What an amazingly useful device it has been.

DIY-Thermocam: A low-cost thermal imager based on the FLIR Lepton sensor

Related Stories