OAK Thermal Accuracy Issues

yishu_corpex

I am using the OAK Thermal camera and trying to detect the temperature of a metallic pipe. I initially first use an thermometer (that has an accuracy of +- 0.2%) to measure the temperature of the metallic pipe and then measuring it using the thermal camera.

Given the range of 30 cm to infinity in the specifications of the camera, I try to do multiple experiments at different distances between 30 cm to 6 ft. I make use of the Thermal Camera example code to carry out these experiments. We move the mouse over the metallic pipe over multiple points and consider the average temperature measurement for each experiment.

I see that at room temperature the the camera and the thermometer readings are around +-3 degree C but when i heat the pipe using a heat gun this difference becomes significantly larger. This can be seen in the image shared below that shows the measurement tables.

Below are the versions of the packages being used for the example script mentioned above.
depthai 2.29.0.0
numpy 2.2.6
opencv 4.11.0.86

I am trying to understand why this might be happening as the error is huge as compared to the specification mentioned in the documentation for OAK Thermal. Your help in this regard would be highly appreciated.

Thanks & Regards
Yishu

jakaskerl

yishu_corpex
If I go by these measurements, I'd say it's probably the calibration that is off. Since you are measuring the radiation of a metallic object, the default values set for emissivity are probably wrong.

However it is not exposed on the depthaiV2, only on V3.
luxonis/depthai-coreblob/v3_develop/include/depthai/pipeline/datatype/ThermalConfig.hpp#L27-L45

Thanks,
Jaka

yishu_corpex

jakaskerl

Thanks for sharing it. I do see in the url that you shared that V3 has a Thermal node.

I have tried 2 things. First I downloaded the v3 develop branch and ran the below command and then ran the thermal_crosshair.py example.
python3 examples/python/install_requirements.py on the branch you want to install

I also installed depthai v3 (2.30) in a separate environment and ran the same example script from there as well.

In both cases i get multiple errors while the code defines the pipeline and also get the error that there is no node named Thermal. I am assuming this isn't supported yet in the current v3 version (2.30) of depthai?

jakaskerl

yishu_corpex
Depthai v3, means depthai versions >3.0.0. Please make sure you have that.

Thanks,
Jaka

yishu_corpex

@jakaskerl

How can I get depthai versions >3.0.0?

All I see on both the depthai-core (C++) and depthai-python the lates release as of May 18,2025 is version 2.30.0.

Thanks,
Yishu

jakaskerl

yishu_corpex
https://stg.docs.luxonis.com/software-v3/depthai/ - here are instructions for both.

Thanks,
Jaka

yishu_corpex

jakaskerl

Thanks, I now have this version of depthai v3.

Thanks,
Yishu