[Qgis-user] [EXTERNAL] Re: Working with second band of two-band GeoTIFF

[Jonas]

Hi Eric,

I checked the image on Mac with QGIS 3.6.3 (homebrew) and both bands are
showing up fine in the Raster Calculator.

Cheers 
Jonas


Alex Mandel-2 wrote
> Eric,
> 
> That is indeed strange behavior. I can not replicate on QGIS 3.4 +
> Linux, hopefully another Mac user can jump in to test. At first I
> thought maybe the lack of band stats but that doesn't seem to be an
> issue. For me I can see it in the Raster Calculator without issue.
> 
> As a workaround, I found in the toolbox "Rearrange Bands" which will let
> you save out specific bands (it's gdal_translate with the -b option).
> 
> +1 for feature request that selecting bands should be on the Save As
> dialog for rasters.
> 
> Also take a look at the Information tab and see if it differs from
> gdalinfo, just to verify QGIS is reading the file correctly.
> 
> Thanks,
> Alex
> 
> On 6/24/19 09:04, Fielding, Eric J (329A) wrote:
>> Alex,
>> 
>> Here is the output of gdalinfo on the file:
>> ======
>> gdalinfo filt_topophase.unw.geo.tif
>> Driver: GTiff/GeoTIFF
>> Files: filt_topophase.unw.geo.tif
>> Size is 4866, 6076
>> Coordinate System is:
>> GEOGCS["WGS 84",
>>     DATUM["WGS_1984",
>>         SPHEROID["WGS 84",6378137,298.257223563,
>>             AUTHORITY["EPSG","7030"]],
>>         AUTHORITY["EPSG","6326"]],
>>     PRIMEM["Greenwich",0],
>>     UNIT["degree",0.0174532925199433],
>>     AUTHORITY["EPSG","4326"]]
>> Origin = (104.507222222222225,28.770277777777778)
>> Pixel Size = (0.000277777777778,-0.000277777777778)
>> Metadata:
>>   AREA_OR_POINT=Area
>> Image Structure Metadata:
>>   INTERLEAVE=PIXEL
>> Corner Coordinates:
>> Upper Left  ( 104.5072222,  28.7702778) (104d30'26.00"E, 28d46'13.00"N)
>> Lower Left  ( 104.5072222,  27.0825000) (104d30'26.00"E, 27d 4'57.00"N)
>> Upper Right ( 105.8588889,  28.7702778) (105d51'32.00"E, 28d46'13.00"N)
>> Lower Right ( 105.8588889,  27.0825000) (105d51'32.00"E, 27d 4'57.00"N)
>> Center      ( 105.1830556,  27.9263889) (105d10'59.00"E, 27d55'35.00"N)
>> Band 1 Block=512x512 Type=Float32, ColorInterp=Gray
>>   NoData Value=0
>>   Overviews: 2433x3038, 1217x1519, 609x760, 305x380, 153x190
>> Band 2 Block=512x512 Type=Float32, ColorInterp=Undefined
>>   NoData Value=0
>>   Overviews: 2433x3038, 1217x1519, 609x760, 305x380, 153x190
>> ===========
>> 
>> I can see that band two has ColorInterp=Undefined. I don't know what that
>> means.
>> 
>> The GeoTIFF file is automatically generated by some SAR interferometry
>> processing scripts we have and it is over 300 MB. The direct link to the
>> file is:
>> http://hysds-urgent-response.s3-us-west-2.amazonaws.com/datasets/interferogram/v1.2/2019/06/09/S1-IFG_RM_M1S2_TN055_20190621T110015-20190609T105947_s1-resorb-1ea6-v1.2-china/merged/filt_topophase.unw.geo.tif
>> 
>> Thanks,
>> 	++Eric
>> 
>> -----Original Message-----
>> From: Alex M <

> tech_dev@

> >
>> 
>>     On 6/23/19 11:11, Fielding, Eric J (329A) wrote:
>>     > I only recently switched to QGIS 3, so I am not sure whether I am
>> missing something that was moved to a different place or the handling of
>> raster layers changed. I am using 3.6.0 on a Mac. I have a two-band
>> GeoTIFF image, and I want to run the Raster Calculator on the second band
>> of the image. When I open the Raster Calculator, it only shows me band 1
>> of the image (image_name at 1). I tried forcing it to use band 2 with @2,
>> but that did not work. I looked at layer Export->Save As and I don’t see
>> a way to save the second band there. I finally went to the terminal and
>> used “gdal_translate -b 2” to save the second band to a separate file. In
>> QGIS 2, it showed me the two bands of the image in the Raster Calculator.
>> Is there a way to do this inside QGIS 3?
>>     > 
>>     
>>     Eric,
>>     
>>     Can you provide a sample 2 band raster file?
>>     Also what does the Information tab in the layer Properties show
>> (should
>>     be similar to gdalinfo)?
>>     
>>     I'm wondering if it thinks your 2nd band is an Alpha/Mask layer and
>>     treats it differently.
>>     
>>     Thanks,
>>     Alex
>>     
>> 
> 
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