Seth, Thanks for the reply. The attached image hopefully will clarify the problem I am having. On the left of the image is the output I would like (I have produced this using a GIS). On the right is the output using mapnik and gdal. The problem is the pixellated effect between the raster values on the RHS.
The GIS isn't that great as far as batch processing is concerned, hence why I am trying to use the GDAL utilities that ship with mapnik. The option in the GIS that produces the desired effect is "anti-aliasing (bilinear interpolation)", but it appears as though there is a more sophisticated smoothing algorithm being employed? I have tried running the various interpolation techniques with gdalwarp but none of them produce a crisp output. I have tried also increasing the resolution of the raster by 5x (both width and height) using "gdal_translate" and "-outsize 500% 500%" this doesn't help either. Any suggestions gratefully received, Chris > Date: Fri, 2 Oct 2009 12:36:24 -0500 > Subject: Re: [gdal-dev] Anti-Aliasing > From: s...@pricepages.org > To: chrisember...@hotmail.com > CC: gdal-dev@lists.osgeo.org > > Could you give an example of the problem? Anti-aliasing generally only > applies when you are going from vector line drawings to rasterized images. > > If I was trying to smooth things I would first look at cubic or bilinear. > Any other resampling may enhance any noise in your image. > ~Seth > > On Fri, October 2, 2009 11:16 am, Chris Emberson wrote: > > > > I am looking for an anti-aliasing function to smooth out the pixellated > > effect between raster values. I have tried the various interpolation > > methods with gdalwarp and have also increased the resolution of the raster > > to try and minimise the effect, to no avail. > > Is this a function to be added soon? > > > > Thanks, > > Chris > > > > _________________________________________________________________ > > Share your photos with Windows Live Photos – Free. > > http://clk.atdmt.com/UKM/go/134665338/direct/01/_______________________________________________ > > gdal-dev mailing list > > gdal-dev@lists.osgeo.org > > http://lists.osgeo.org/mailman/listinfo/gdal-dev > > _________________________________________________________________ Learn how to add other email accounts to Hotmail in 3 easy steps. http://clk.atdmt.com/UKM/go/167688463/direct/01/
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