Difference between revisions of "Downscaling raster maps"

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'''Q:''' What is be the recommended way to downsample a raster map?
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'''Question'''
  
'''A:''' The "best" way is subjective, but the main options are
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What is be the recommended way to downsample a raster map?
r.resamp.interp, r.resamp.stats, r.resamp.rst, r.mfilter.fp, or any
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 +
'''Answer'''
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The "best" way is subjective, but the main options are
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{{cmd|r.resamp.interp}}, {{cmd|r.resamp.stats}}, {{cmd|r.resamp.rst}}, {{cmd|r.mfilter.fp}}, or any
 
combination of those.
 
combination of those.
  
Another option is to use i.fft followed by i.ifft with a mask applied.
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Another option is to use {{cmd|i.fft}} followed by {{cmd|i.ifft}} with a MASK applied.
However, that requires that your raster contains no null cells (so you
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However, that requires that your raster contains no null cells
may need to use e.g. r.fillnulls first), and it also requires that you
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(so you may need to use e.g. {{cmd|r.fillnulls}} first), and it also requires that you
can fit the entire raster in memory (so it isn't suitable for very
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can fit the entire raster in memory (so it isn't suitable for very high resolution data).
high resolution data).
 
  
 
[[Category: FAQ]]
 
[[Category: FAQ]]

Revision as of 08:54, 5 February 2013

Question

What is be the recommended way to downsample a raster map?

Answer

The "best" way is subjective, but the main options are r.resamp.interp, r.resamp.stats, r.resamp.rst, r.mfilter.fp, or any combination of those.

Another option is to use i.fft followed by i.ifft with a MASK applied. However, that requires that your raster contains no null cells (so you may need to use e.g. r.fillnulls first), and it also requires that you can fit the entire raster in memory (so it isn't suitable for very high resolution data).