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Seth,<br><br>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.<br><br>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.<br><br>Any suggestions gratefully received,<br><br>Chris<br><br><br><br><br>> Date: Fri, 2 Oct 2009 12:36:24 -0500<br>> Subject: Re: [gdal-dev] Anti-Aliasing<br>> From: seth@pricepages.org<br>> To: chrisemberson@hotmail.com<br>> CC: gdal-dev@lists.osgeo.org<br>> <br>> Could you give an example of the problem? Anti-aliasing generally only<br>> applies when you are going from vector line drawings to rasterized images.<br>> <br>> If I was trying to smooth things I would first look at cubic or bilinear.<br>> Any other resampling may enhance any noise in your image.<br>> ~Seth<br>> <br>> On Fri, October 2, 2009 11:16 am, Chris Emberson wrote:<br>> ><br>> > I am looking for an anti-aliasing function to smooth out the pixellated<br>> > effect between raster values. I have tried the various interpolation<br>> > methods with gdalwarp and have also increased the resolution of the raster<br>> > to try and minimise the effect, to no avail.<br>> > Is this a function to be added soon?<br>> ><br>> > Thanks,<br>> > Chris<br>> ><br>> > _________________________________________________________________<br>> > Share your photos with Windows Live Photos – Free.<br>> > http://clk.atdmt.com/UKM/go/134665338/direct/01/_______________________________________________<br>> > gdal-dev mailing list<br>> > gdal-dev@lists.osgeo.org<br>> > http://lists.osgeo.org/mailman/listinfo/gdal-dev<br>> <br>> <br> <br /><hr />New! Receive and respond to mail from other email accounts from within Hotmail <a href='http://clk.atdmt.com/UKM/go/167688463/direct/01/' target='_new'>Find out how.</a></body>
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