Frank, Fodder, There is a nice open source implementation of interpolation on TerraLib.org [1] that takes any vector and produces a raster based on nearest neighbor, average nearest neighbor, distance weigh average nearest neighbor, box interpolation and average box interpolation.
Best regards, Ivan [1] http://terralib.org/html/v320/html/class_te_interpolation_algorithms.html > -------Original Message------- > From: Frank Warmerdam <[EMAIL PROTECTED]> > Subject: Re: [Gdal-dev] Algorithm Development > Sent: Sep 09 '08 03:22 > > Fodder wrote: > > > > > > Frank Warmerdam-2 wrote: > >> > >> - An algorithm for interpolation in regions of a raster. > >> > >> > > > > Hi Frank, > > > > Happy to hear about your research. I'm interested in the interpolation in > > regions of a raster algorithm. In particular: > > - What interpolation methods with be supported? > > Fodder, > > A simple "four quadrant inverse distance" interpolation is used. That is, > I find the closest valid pixel for each of the four quadrants and then > mix them based on inverse distance weighting. > > Then I apply some number of 3x3 average filtering in the interpolated areas > to smooth out various artifacts somewhat. > > While this approach has a number of problems, I feel it is suitable for > use in a variety of circumstances, including sparse data (such as might > be the result of burning a bunch of known sample points into a raster), > holes in data (such as SRTM or interferometry DEM holes), or to interpolate > in data after burning contours into a raster. > > This is in contrast to approaches such as the spline interpolation in > GRASS which produces (presumably) superior results when interpolating in > modest sized holes in rasters but that does not scale well to sparse data > or to large empty regions like with contours. > > > - What vector sources will be supported (if any) (points only, or polyline > > polygon etc)? > > The fill algorithm does not directly use vector data. If you want to produce > raster data by interpolating from vectors you would need to first use > gdal_rasterize to turn the vectors into a raster, and then use the fill > program/functions to interpolate in the holes. I believe someone > (Andrey? Even?) has been improving gdal_rasterize to support additional > data types. > > > - Will it be incorporated in Gdal_Grid? > > No. I'm only moderately familiar with gdal_grid but my understanding > is that it does not scale particularly well to handling huge numbers of > points to interpolate from. But generally speaking gdal_grid will still > be much superior for interpolating reasonable amounts of point data > to build a raster. > > > - When you say regions, do you mean vector polygons or raster zones? > > Raster zones. > > Note that this algorithm is already in trunk as the function > GDALFillNodata(). However, I've had some problems with the post > fill smoothing filtering and haven't really finished cleaning things > up and documenting them. > > Best regards, > -- > > ---------------------------------------+-------------------------------------- > I set the clouds in motion - turn up | Frank Warmerdam, [EMAIL PROTECTED] > light and sound - activate the windows | http://pobox.com/~warmerdam > and watch the world go round - Rush | Geospatial Programmer for Rent > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev > _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev