Flir lepton 3.5 - raw image capture from Raspi 4b python

Hi there,
I have a flir lepton 3.0 on a pure thermal 2 breakout board connected to a raspberry pi 4b via a micro usb cable.
I am trying to use a python program on the raspi to capture raw thermal images from the lepton 3 which i can then process with python and open CV to filter out the pixels in the image which are above a certain temperature.
Problems I am having are:

  • lepton 3.0 is non-radiometric and from what I can see, this cannot be used to calculate the actual temperature values of each pixel - although it’s not clear why.
  • i’d like to stick with the lepton 3 series due to it’s higher resolution and so would need to go for a lepton 3.5. The questions on this are:
  1. Do you sell stand alone Lepton 3.5 cameras? - it doesn’t appear so on your site so might have to go via mouser or digikey but with extra lead time from US I suppose.
  2. Can I get raw thermal images either via the micro usb cable or via the SDA, SCL, RX and TX pins on the pure thermal 2 board pins from a python program on the raspberry pi 4b? Despite a lot of searching, I haven’t been able to get an answer on this online. I’ve also messaged flir support but they haven’t got back to me at all.

Hi Nick,

Having a look at this, I’ve come up with the following answers:

  1. Unfortunately, as you’ve probably worked out, we only sell the Lepton as a complete module with the PureThermal Mini Pro:
  2. The python code you linked uses USB as far as I can tell, using LibUVC (A usb video library):

Keen to see this working as I’m sure someone else will want to do this in future!

Hi James, thanks a lot for your reply - very useful to know that the LibUVC identifies that it’s communicating via the usb cable - kind of obvious now i look at it again. Re my question, do you know if the OpenGL with full KMS is used by the raw data transfer or is it just used if you’re using the Get Thermal app to get the images/video?
‘on the 4b it’s not possible to run OpenGL desktop driver with full KMS but I’m not sure if this is required if you’re not using the Get Thermal software app to get the images.’