Import Landsat 7 & 8 thermal images - Dragonfly

RafaelA · November 9, 2018, 12:23pm

Hi all,

Has someone managed to import Landsat 7 & 8 thermal images through Dragonfly?
I´ve got Landsat 4-5 working pretty well, but when I try with more recent versions it produces unexpected results. I guess there are some small modifications to the band/file naming and metadata structure.

I´ve seen it on the list for Dragonfly+ (which looks very promising!), but perhaps someone has a workaround in the meantime.

Rafael

chris · November 9, 2018, 11:01pm

@RafaelA ,

I am sorry to say that I have not yet added support for LANDSAT 7 and 8 images in the Dragonfly plugin or core libraries yet. As soon as I finish cleaning up the UWG API in Dragonfly+ (which should be pretty soon), I think the next priority will be to build objects for LANDSAT images and I will do it correctly this time (the LANDSAT 5 support in Dragonfly Legacy plugin is very hacky).

The best workaround that I can give you for now is that I think the conversion formulas for going from digital numbers for the thermal TIFF image to temperature in Celcius are pretty similar to those used in LANDSAT 7+8:

github.com

chriswmackey/Dragonfly/blob/master/src/DF Import LANDSAT Image.py#L248-L253


color = img.GetPixel(xVal, yVal)
DN = color.R/255
cellRadiance = radianceMin + (DN*radianceDiff)
cellTempKelvin = 1260.56 / math.log((( 607.76 * 0.95) / cellRadiance) +1)
cellTempCelcius = cellTempKelvin - 273.15
temperatureValues.append(cellTempCelcius)

So, if you grab the right thermal image TIFF from a LANDSAT 7 image, I think you can use the same formulas to get temperature.

RafaelA · November 15, 2018, 2:00pm

Thanks for the update Chris!
The formulas are very useful, I´ll try to play around with them and see if I manage to make it work in the meantime.
Rafa

MichaelEsposito · March 24, 2021, 2:04pm

Hi @RafaelA and @chris, Has there been any updates to the LANDSAT image processing workflow since this last discussion?