Building usable thermal camera with Raspberry Pi

[Vlad Ross]

Hello,

I think a lot of people here purchased Lepton for building portable thermal camera.
In this post I'm trying to determine main points to achieve this goal.

Essential features:
- Video display
- Hold and save frame as image
- Palletes: BW, ironbow, rainbow
- Calibrating, temperature scale display

I suppose our best choice for building such thing is Raspberry Pi and small TFT car display with composite input.
Hardware buttons could be used for operation control.

Questions:

1) We need to draw temperature color scale on the screen for reference. Is it possible?
Can radiometry help us (Datasheet 8.4)? I see curve plot in the doc, but it captioned as hypothetical...

2) If color scale requires calibration, how can we calibrate Lepthon before using?
May be we can use some plate with attached thermal sensor? Or even heated plate?

3) What about overlaying transparent image from webcamera?

4) How do you think: is it possible to get "macro" shots with Gallium Arsenide lens like in this video - https://www.youtube.com/watch?v=Lie771fzBaw  ?

BTW, thanks PureEngineering and tz for their code contribution.

P.S. Sorry for my English.

[tz]

- Video display

This can be an SPI LCD or similar, as well as NTSC/PAL or HDMI, however the use of SPI might slow down the lepton fram rate (until we have a kernel driver that can do spi-dma; the TFT can, the usermode spi can't).

The odroid-w is a compact pi clone with a tft backpack and battery, there are similar (larger) ones. See adafruit.com for products and tutorials.

I also have a "tft car display". They are about the same price, but the car display has a mirror mode so the image is as if I'm looking into a mirror (left-right is direct instead of exchanged).

- Hold and save frame as image

We get the raw values. My grayscale PNG save does this, as well as my BMP. These can be processed and converted. Or even stored as a lossless video stream.

- Palletes: BW, ironbow, rainbow

This is simply the lookup table

- Calibrating, temperature scale display

1) We need to draw temperature color scale on the screen for reference. Is it possible? 
Can radiometry help us (Datasheet 8.4)? I see curve plot in the doc, but it captioned as hypothetical...
2) If color scale requires calibration, how can we calibrate Lepthon before using? 
May be we can use some plate with attached thermal sensor? Or even heated plate?

This I'm unsure of, but I think it is linear (or close enough) so you would need one known temp. It is normally done by closing a shutter with an accurate temp sensor to get a baseline.

This would be useful in a contour mode where the colors would loop every 10 or 20 degrees F or C. The color itself would show the lowest digit ofmthe temp.

3) What about overlaying transparent image from webcamera?

I'm doing it with the pi camera, there is a mode to overlay video, but a usb webcam could work as well, just read and merge the frames.

[sa...@pureengineering.com]

you may be interested in this. 

https://groupgets.com/campaigns/43-flir-lepton-demo-camera-batch-1

if enough people buy this we may be able to reverse engineer this guy and put our custom firmware into this thing. 

I will be working on getting the programming pinout. 

[tz]

This is part II https://www.youtube.com/watch?v=SKLnGhwWtoc which goes into the FLiR One for iPhone 5 probing the buses - I would assume the demo camera would share as much as possible with it.
(Part 1 is the actual teardown.  I would like to get a silicon or whatever protective lens).

I'm on the list for one.  If someone just wants a thermal camera, this would be easier than trying to do wiring.

[Randy Mackay]

Good discussion going on.  I've joined the campaign for a few of the lepton sensors breakout boards and the demo camera.

Like many others, my aim is to put it on a UAV, in particular on an ArduCopter based UAV multicopter.  The low-ish resolution will probably make it not quite as useful as some hope but it's a start and there's nothing like it at this price.

Keeping it all small would be great, so either reverse engineering the demo camera or alternatively there was a discussion some time back of making an Intel Edison interface board for it in place of a RPi.  This would be really great because of it's reduced size and on the arducopter dev team we're already familiar with the intel edison (although we're also familiar with the RPi and Odroid).  The flight controller would communicate with the Intel Edison using a serial port, we'd probably use "MAVLink" and then call whatever libraries we have to trigger the picture taking and storing of images.  Ideally we might add the vehicle's current location (lat, lon, altitude) and attidue (roll, pitch, heading) into the images using EXIF.

Anyway, thanks again to the PureEngineering guys for making this possible!

[sa...@pureengineering.com]

Some great news for those interested in the demo camera. 

Flir released a SDK for the board!

more information is posted up on this site here:

http://www.pureengineering.com/projects/leptondemo

and direct link

https://drive.google.com/file/d/0B3wmCw6bdPqFTVNRMmlDeVY0ODA/view?usp=sharing