[GRASS-dev] Re: [GRASS GIS] #549: r.mfilter should _respect_ i.fft outputs for use with i.ifft

[GRASS GIS]

#549: r.mfilter should _respect_ i.fft outputs for use with i.ifft
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  Reporter:  nikos        |       Owner:  grass-dev at lists.osgeo.org
      Type:  defect       |      Status:  new                      
  Priority:  major        |   Milestone:  6.4.0                    
 Component:  Raster       |     Version:  svn-develbranch6         
Resolution:               |    Keywords:  i.fft, r.mfilter, i.ifft 
  Platform:  Unspecified  |         Cpu:  Unspecified              
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Comment (by glynn):

 Replying to [ticket:549 nikos]:

 >   Is it fair enough to ask for this support?[[BR]]

 It's already present in 7.0, but the interface had to be changed (separate
 maps for the real and imaginary components), so it's unlikely to be back-
 ported.

 >   Or is there a reason why _r.mfilter_ alters the i.fft-products in such
 a way that _i.ifft_ can't handle?

 i.fft stores the actual frequency-domain data in auxiliary data files. The
 output map only exists for viewing with d.rast. Apart from anything else,
 a raster map can only store real values, and the FFT results are complex
 values.

 i.ifft operates upon the auxiliary data files, not the map itself, so it
 only works with maps which were generated by i.fft. The only processing
 which can be performed on the frequency-domain data is to apply a mask
 (i.ifft explicitly applies the MASK raster if it exists).

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Ticket URL: <http://trac.osgeo.org/grass/ticket/549#comment:2>
GRASS GIS <http://grass.osgeo.org>