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Thermal Temperature Conversion

6X Series Sensors - Thermal Temperature Conversion

Introduction

.Tif files from the 6X Thermal and 6X Thermal Pro are recorded in CentiKelvin (Kelvin * 100). To view thermal data in celsius, you must first convert it. This can be achieved with Sentera's Radiometric Correction Tool, as well as free imagery software.

Sentera's Radiometric Correction Tool

To convert individual .Tif files from CentiKelvin to Celsius, run your images through Sentera's radiometric correction tool.

Radiometric Corrections Script

This program is primarily designed to correct for lighting in 6X Imagery. It will additionally convert 6X Thermal Images from CentiKelvin to Celsius.

Thermal Temperature Conversion Formula

To convert individual .Tif files, or stitched maps, from CentiKelvin to Celsius, use the following formula:

Degrees Celsius=DNLWIR100273.15Degrees\ Celsius = \dfrac{DN_{LWIR}}{100} - 273.15

This formula can be used in imagery software to perform the conversion. For example, in QGIS, use the raster calculator to input the equation.


Grey Images

Raw 6X thermal images will appear solid grey when viewed on most basic image viewers (ex. Windows Photo Viewer). The color scale on a basic photo viewer is set to the range of all possible temperatures that the 6X thermal sensor can record; Black being the coldest and white being the hottest. Relative to the range of possible temperatures, the range of temperatures recorded in a typical 6X image is relatively small. This relatively small range is somewhere in-between the coldest (black) and hotest (white) extremes, causing the image to appear as a nearly constant grey.

Grey image example

Most advanced imagery software will automatically adjust the displayed color range to match the range of temperatures recorded in an image. As a result, raw images viewed using most GIS tools will highlight the temperature differences you'd expect to see in a thermal image.

The image shown below is the same "grey" image seen above, but as it appears in Irfanview. QGIS and other GIS tools will similarly convey the temperature differences in raw imagery.

detailed image example

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