[gdal-dev] Get real and turf imaginary from complex float...

[Derek Mueller]

Thank you Frank,

I think I should have said, how do I get both the real and imaginary 
numbers out as Float32, since ultimately I do want to calculate 
magnitude (as you might have guessed). Then I could read the 'real' and 
'imaginary' numbers into IDL as 2 separate tiffs do do the calculation. 

I tried to import the CFloat32 directly into IDL/ENVI but it doesn't 
like the '64-bit pixel'.  Could there be a workaround by modifying tiff 
tags to say the CFloat32 data are actually 2 separate 32-bit numbers?

Thanks,
Derek


Frank Warmerdam wrote:
> Derek Mueller wrote:
>> I am new to gdal and it looks very promising ...but I am trying to 
>> make a geotiff with four bands from an RSat-2 SLC image but I don't 
>> need or want the imaginary part of the CFloat32 for now.
>>
>> So far I have been able to extract the data and warp it to my 
>> favourite projection.  Can gdal separate the CFloat32 and save the 
>> just real part?
>>
>> gdal_translate.exe "RADARSAT_2_CALIB:SIGMA0:product.xml" out.tif
>> gdalwarp -s_srs wgs84.prf -t_srs aeaIS.prf -r bilinear out.tif image.tif
>
> Derek,
>
> gdal_translate "RADARSAT_2_CALIB:SIGMA0:product.xml" -ot Float32 out.tif
>
> should be sufficient to discard the imaginary portion.  I'm not aware 
> of any
> easy way of taking the magnitude of the data which is also often 
> desirable.
>
> Best regards,

-- 

*Derek Mueller
*Roberta Bondar Fellow in Northern and Polar Studies
Geography Department, Trent University
1600 West Bank Drive,
Peterborough, ON K9J 7B8
Tel: (705) 748-1011, ext. 7153,
Fax:  (705) 748-1205
E-mail: dmueller at trentu.ca

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