[GIS] Converting Landsat8 DN to TOA reflectance for use in envi

envigrasslandsat 8

I am used to working in envi, however my current version does not support Landsat8.
I downloaded GRASS for the express purpose of converting Landsat8 DN to TOA reflectance for use/analysis in envi.

I have managed to do the conversion fine using the tutorial provided (http://courses.neteler.org/processing-landsat8-data-in-grass-gis-7/#Unpacking_the_downloaded_Landsat_8_dataset), however once I try to export that to a format usable by envi, I get stuck.

I have tried "r.out.tiff":
However get this warning:
"WARNING: Raster map > is a floating point map. Fractional values will be rounded to integer"

When I load it in envi it is clear that the image quality has decreased and it is no longer suitable for my analyses.

When I try "r.out.gdal":
I get the following error message: "ERROR 6: SetColorTable() only supported for Byte or UInt16 bands in TIFF format."

And when I try to open it in envi, I get this message: "Cannot open in envi: unsupported number of bits per pixel"

Can anyone help me please?

Best Answer

You can open the images in ENVI (band by band) and apply the equations of this paper:

  1. DN to Radiance
  2. Radiance to Reflectance

the parameters are inside the metadata (*.mtl)

  • gain= RADIANCE_MULT_BAND
  • offset or bias= RADIANCE_ADD_BAND
  • date=DATE_ACQUIRED
  • cos(tetha)=sen(SUN_ELEVATION)
  • d=EARTH_SUN_DISTANCE
  • landsat 8 doesnt need ESUN

also in the metadata you can find the k1 and k2 for temperature.

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