[GRASS-user] troubles with i.landsat.rgb and d.rgb

[Renae Mackas]

Thanks for your input, and sorry for the delayed response Hamish, I've been
away for the last while and haven't had much chance to work with Grass.  



Hamish wrote:
> 
> 
> Renae Mackas wrote:
>> I have used r.ing.dal to import different Landsat TIFF images, and am now
>> trying to superimpose red, green, and blue spectral bandsto get  "real
>> colour" images.
>> 
>> I am under the impression that I need to use i.landsat.rgb to
>> auto-balance the colours of the LANDSAT images I am using.
> 
> you do not "need" to use i.landsat.rgb, it just helps brighten things up
> if the image comes out rather dark. example:
>   http://bambi.otago.ac.nz/hamish/grass/landsat/
> 
> The reason that I wanted to try and use i.landsat.rgb is that when I have
> been doing r.composite with the Landsat images, the resulting composite
> images come out with a coloured tinge to them (I am putting together
> images of sea ice formations, and most r.composite images come out with a
> pinkish/purple tinge). I thought I might be able to avoid this using
> i.landsat.rgb.  Perhaps this was an incorrect assumption?
> 
> 
>> I am using a PC, using the native version.
> 
> does that mean you are running MS Windows?  native or cygwin version?
> (sorry to be overly pedantic, but consider that many run linux on a PC,
> and that historically many/most? GRASS users use some flavour of Linux)
> 
> Yes, I am using MS windows, using the native version
>> and when I run the command:
>> i.landsat.rgb red=020.020.2000.055_B30
>>    green=020.020.2000.055_B20
>>    blue=020.020.2000.055_B10
>>
>> a microsoft windows window pops up that informs me " r.univar.exe has
>> stopped working- a problem caused the program to stop working correctly. 
>> Windows will close the program and notify you if a solution is vailable". 
>> As long as I continue to run the i.landsat.rgb command,
>> this window continues to pop up.
> 
> can you run "r.univar 020.020.2000.055_B10" from the command prompt?
> 
> Yes, I could run this.
> 
> 
>> Have I made a mistake somewhere??
> 
> don't really know. might be an install problem.
> 
> can you view the scene ok in QGIS? (www.qgis.org)
> 
> 
>> Also, once (if?) I do get i.landsat.rgb to work, will the map display
>> window automatically show me the superimposed images??
> 
> no. if you are currently viewing the layers you have to do a "hard"
> redraw as the GUI isn't aware that the colors have changed behind its
> back and the existing view may be partially cached.
> 
> How do I do a "hard" redraw to be able to see the result of i.landsat.rgb? 
> What I ultimately want is a mosaic image of multiple Landsat images.  If I
> do end up using i.landsat.rgb, do end up doing the "hard redraw" with my
> final mosaiced image, or do I have to do it seperately with each image
> that I want to put into the mosaic?
> 
>> Also, I have tried just running d.rgb on the same images:
>> 
>> d.rgb red=020.020.2000.103_B30 blue=020.020.2000.103_B20
>> green=020.020.2000.103_B10
> 
> if this is the native build d.rgb shouldn't work from the command prompt,
> as there are no xmon to draw to (d.mon + UNIX's X-Windows). Instead use
> the 'Add RGB or HIS layer' button from the GIS manager.
> the cygwin version uses X-Windows (aka X11) and so allows xmons.
> 
> I tried using the button, and it displayed well, thank you.
> 
> good luck,
> Hamish
> 
> 
> 
>       
> 
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> 

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