[GRASS-user] Exporting RGB Composite Images to GeoTIFF

[Michele Toma]

Hi Markus, everyone,

Thank you for your all of the information.

As for the i.fusion.hpf method, I am unable to install on Windows 7 with GRASS 7.0.4. The g.extention module does not allow me to connect to github to install the extension as noted in the g.extension documentation page. If I understand what I read correctly, I would need to download and install the Source Code version or version 7.2. Also, Moritz Lennert’s reply stated that it works in 7.2 but not in 7.0 which I have been using.

I was able to resolve my issue (export the composite image so that it can be opened in Global Mapper and Photoshop) by opening it in QGIS using the GRASS Tools plugin. Click “Add raster layer” button and navigate to the composite image and click OK. Once it was added to QGIS, I right-clicked the raster layer in the Layer menu and selected the Save As… option. Then in the Save As… window, I selected “rendered image” as the output and left all other options as the default. This newly exported image allowed me to open the it in other programs.

Thank you,

Michele Toma
michele.toma at airborne.aero<mailto:michele.toma at airborne.aero>
www.airborne.aero

[New Small2]

From: neteler.osgeo at gmail.com [mailto:neteler.osgeo at gmail.com] On Behalf Of Markus Neteler
Sent: Thursday, July 21, 2016 7:28 AM
To: Michele Toma
Cc: grass-user at lists.osgeo.org
Subject: Re: [GRASS-user] Exporting RGB Composite Images to GeoTIFF

Hi,

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