Autel Evo II Dual 640T V3 Temperature Values

PIX4Dmapper
1

Hello,

I used an Autel Evo II Dual 640T V3 to capture thermal imagery of a field for the purpose of making an orthomosaic. I was able to generate a thermal orthomosaic, however I am unsure how to convert the pixel values to their proper temperature values (the sensor is radiometric).

The range of values as shown in the image below is between 2960 and 3085, and the higher values do correspond to the warmer areas. The processing thermal images page provides guidance for converting these values for other cameras, but none of the equations would appear to be applicable to my drone. Does anyone have any experience with getting the actual temperature values to display?

The thermal camera generates .JPG, .IRG, and .TIFF files. I used the TIFF tiles to construct the orthomosaic.

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Hi @nburner ,

Is the dataset in RJPG format? When using a radiometric JPG (RJPG) dataset, creating a thermal reflectance map with absolute temperature is possible.

The values are relative when the thermal images are not in the RJPG format. This means PIX4Dmapper can still create a reflectance map based on the RGB bands or Greyscale information, but the map you see only provides visualization of where it might be hotter or colder.

For a better visualization, feel free to change the Colors Distribution to Thermal.

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If you have further questions about this, I am happy to answer them.

Best regards,
Rosana (she/her)

3

The imagery is not in RJPG format. The Evo II provides 3 files per thermal image: a pseudocolored .jpg, a .tiff, and .irg file (shown below). I used the .TIFF to generate the orthomosaic. The “Processing Thermal Images” article does mention TIFF as being an acceptable format, and that it “can lack important radiometric data”. From what I have read online, people are saying that the TIFF does include radiometric data.

Would I need to convert these images into an RJPG for them to work with Pix4Dmapper, or am I completely doing something wrong?

Thanks

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2 Likes
4

Yes I’m too in need of answer to this query!!
How to use .tiff imagery from evo 2 thermal to thermal maps

5

Pls do answer the next question ! That would help autel thermal users and me!!

7

The formula I used to get the .tiff values in Celsius was:

thermal_ir*0.1-273.15

I found this formula about a year ago on the autelpilots.com forum, but am unable to locate the thread.

1 Like