[Mapserver-users] Smoothing NEXRAD imagery

[Frank Warmerdam]

Daryl Herzmann wrote:
> I have been working on generating maps of current NEXRAD (Weather 
> Service RARAR) imagery and overlaying observations.  This is currently 
> working great, except the pixelation that occurs at very close range.  
> Does anyone know how to implement an automatic TIFF smoothing algorithm at 
> close ranges?
> 
> Here is a page with an example of what happens to the NEXRAD image at 
> close ranges...  The pixelation at 25km is not that bad and will probably 
> be what I live with for the final app.

Daryl,

If you are using MapServer 3.7 from CVS there is a LoadGDALImage() function
in mapdrawgdal.c that is responsible for most imagery loads from GDAL. It
would be relatively easy to add a processing option to the map file that
would direct this function to load oversampled imagery with some sort of
smoothing - nearest neighbour or cubic convolution for instance.

If you are feeling ambitious go ahead and take a crack at it.  The processing
arguments are generic all your changes would be in this one function.

The special case to watch for would be when src_xsize > dst_xsize or
src_ysize > dst_ysize.  Just modify the code to loading into a data array
at the source resolution and resample appropriate into the output buffer.

I could do this, but I have little time available.  Of course if you wanted
to pay I am sure someone would be happy to do it.

Best regards,

-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent