2

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?

  • Please consider to use a recent GRASS GIS 7 package for this task. – markusN Nov 15 '14 at 13:37
  • Landsat 8 OLI data is already in a TOA reflectance-like format. What you need to do is simply multiply by 2e-5 and subtract 0.1 . You can do the above in ENVI using band-math. Remember to use float(b1) to force the conversion into floating point from integer. This approach functions for bands 1 through 9. – Mikkel Lydholm Rasmussen May 13 '15 at 6:30
1

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.

0

The error message come really from GDAL which is used by GRASS GIS for the export to GeoTIFF. It sounds overly dramatic, in fact only the color table gets lost during the export because the GeoTIFF format does not support floating point color tables (GRASS does).

You may export to ENVI format right away: http://www.gdal.org/frmt_various.html#ENVI by selecting format=ENVI.

-2

You can use QGIS, with the GeoSud TOA plugin:

The plugin is dedicated to Geosud data. However, it should be used for satellite images acquired in other ways. It converts Digital Numbers (DN) to Top of Atmosphere (ToA) Reflectance for three types of instrument : RapidEye, Spot 5 and Landsat 8.

  • 1
    It would be helpful to include some information about the plugin and where to find it in your answer, possibly a link. Note the summary of what it can do or how it can solve the problem is more important than the link. – Chris W May 12 '15 at 20:00

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