Lepton 3.5, Help with "Get object temp"

OpenMV Products
1

Hello, The Flir Lepton 3.5 works really well, but I’m having a hard time understanding the relationship between the Threshold values and the min & max temperature.

I would like to read/measure temperatures around 180C. It would be nice to know a litter more about the relationship between the two so I can get the temperatures above 35C.

Thank you for your help, sorry if I missed something.

Color Tracking Thresholds (Grayscale Min, Grayscale Max)

threshold_list = [(200, 255)]

Set the target temp range here

min_temp_in_celsius = 20.0
max_temp_in_celsius = 35.0

2

It’s simply:

(max_temp_in_celsius - min_temp_in_celsius) / 255

Each pixel value… 0-255 is then mapped to the range you said. In your case above 1 LSB is worth ~0.05C (0.05882352941176470588235294117647)

The image processing library doesn’t understand temp. So, it’s looking at the pixel values. Which in this case are 200*~0.05C + 20C ~= 31.7C and 255*~0.05C + 20C ~= 35C

3

Thank you for the quick response!!

4

please also see that:

  • Scene Dynamic Range - High Gain Mode: -10° to +140°C; Low Gain Mode: -10° to +400°C (at room temperature), -10° to +450°C (typical)
    so you have to deal with low gain mode for this temps i think…
1 Like