[GRASSLIST:4454] Re: Temperature from LANDSAT-TM5 ch.6

[Hamish]

> I'm looking at some LANDSAT-TM5 data and I'd like to derive surface
> temperature from channel 6 (thermal IR) as described in Neteler &
> Mitasova (1st ed.) S9.4.3.
> 
> The results look all wrong though, I'm getting a range of -54 to +69 C
> 
> Using the following formulae:
> 
> radiance = 1.238+(15.6-1.238)*tm6/255.0;
> temp_kelvin = 1260.56 / log(607.76/radiance + 1);
> temp_celsius = temp_kelvin - 273.15
> 
> we get:
> 
> tm6(0) = -69.7787 deg C
> tm6(255) = 68.6640 deg C
> 
> Using d.histogram on the "tm24r_b6" 8bit GeoTIFF input raster, I see a
> bimodal distribution with peaks at 75 (land) and 220 (ocean). That
> translates to -6deg for the land and +57deg for the ocean...
> 
> is my satellite data wrong or is it the conversion formulae?


It appears my data is missing all calibration coefficients; I was
assuming these were standardized. Apparently not.

... back to the vendor

,
Hamish