[GRASS-user] Exporting RGB Composite Images to GeoTIFF

[Markus Neteler]

Hi,


On Thu, Jul 21, 2016 at 2:53 AM, Michele Toma <michele.toma at airborne.aero>
wrote:

> Hi everyone (again),
>
>
>
> I am having trouble exporting a composite RGB image into a GeoTIFF format
> that I can open in Global Mapper, Photoshop, or other programs. This is
> using Landsat 8 imagery. I am able to open the composite image in QGIS, but
> not in Global Mapper or Photoshop.
>
>
>
> Below is a list of steps that I took to get the image. I am unsure of what
> settings to use when using r.out.gdal to export my image so that it works
> in other programs. I am using GRASS 7.0.4.
>
>
>
> 1.       Import Landsat 8 imagery
>
> 2.       Convert the DN to reflectance/radiance
>
> a.       i.landsat.toar input=LC81100362016082LGN00_B
> output=LC81100362016082LGN00_refl metfile=LC81100362016082LGN00_MTL.txt
>
> 3.       Perform pansharpening with i.fusion.brovey addon
>
> a.       i.fusion.brovey -l ms1=LC81100362016082LGN00_refl2 at Osaka
> ms2=LC81100362016082LGN00_refl3 at Osaka
> ms3=LC81100362016082LGN00_refl4 at Osaka
> pan=LC81100362016082LGN00_refl8 at Osaka output_prefix=brovey
>

BTW: this method is superior (the addon can be installed with g.extension):
https://github.com/NikosAlexandris/i.fusion.hpf

[...]


> Another method that I have tried using an example on the r.out.gdal
> documentation page:
>
>
>
> i.group group=brovey_group input=brovey.red,brovey.green,brovey.blue
>
> g.region rast=brovey.blue -p
>
> r.out.gdal in=brovey_group output=brovey_group.tif type=Float64 \
>
>   createopt="PROFILE=GeoTIFF,INTERLEAVE=PIXEL,TFW=YES"
>
>
>
> The result is an image with distorted colors when opened in QGIS. Water
> has turned a reddish brown color.
>
>
>
> [...]
>

Please try to create the group in order B G R, not R G B:

i.group group=brovey_group input=brovey.blue,brovey.green,brovey.red

and then export it as above.

Best,
Markus


-- 
Markus Neteler
http://www.mundialis.de - free data with free software
http://grass.osgeo.org
http://courses.neteler.org/blog
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