Hello, dear GRASS users.<br><br>A few words about new <a href="https://lpdaac.usgs.gov/about/news_archive/monday_october_17_2011">ASTER GDEM version 2</a>.<br><br>As was explored, this DEM could be also rather well filtered and smoothed with the <a href="http://personalpages.manchester.ac.uk/staff/neil.mitchell/mdenoise/" target="_blank">Sun's denoising algorithm</a> (using <GDAL> and free / open source program <mdenoise>). Also there is GRASS add-on <a href="http://grass.osgeo.org/wiki/GRASS_AddOns#r.denoise" target="_blank">r.denoise</a>.<br>
<br><span lang="en"><span>Experiments showed that</span></span> the best smoothing of ASTER GDEM 2 <span lang="en"><span>is reached with such parameters of <mdenoise>:<br>
</span></span><br>threshold<span> = 0.8<br></span><span></span>iterations<span> = </span><span>10-20<br><br>Also </span>filtering with <r.neighbors> by "average" method and window size >=5 is quite usefull to remove some noise from DEM. <br>
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With the best regards from Russia,<br><font color="#888888">Alexander Muriy. </font></span>