Interpolate image

[Pål Kristensen]

Thanks for the help!! I really appreciate the quick response.

Would it be an idea to add the information provided in the MS RFC 4 to the
raster how to document? It is mentioned in the RFC that the documentation
should be updated with the new processing functionality provided. Is far as
I can see this is not the case, many other processing options is described
in the raster how to, but not the resample option.

At the moment the information on how to resample the output is quite hard to
find (especially for a Mapserver noob like me :-) ). The result of using an
other resample method than nearest neighbor is dramatically increasing
output quality in some cases when dealing with rasters. I think it would be
nice to add this to the raster how to, so that others don't have to dig into
the development section of the site to find it.

Anyway, thanks again for the help!

Regards,
Pål Kristensen
Norwegian Mapping and Cadastre Authority


Daniel Morissette-2 wrote:
> 
> I think Guillaume is correct that AGG's main advantages are on the 
> vector side and unless I'm mistaken you won't see much difference with 
> rasters. Thomas or others who worked on AGG support can correct me if 
> I'm wrong.
> 
> Back to Pål's question, if I understood correctly, you're looking for a 
> way to do bilinear resampling. This has been supported since MapServer 
> 4.8, see RFC-4 for the details:
>    http://mapserver.gis.umn.edu/development/rfc/ms-rfc-4
> 
> Note that bilinear resampling was not working for AGG output in 
> 5.0.0-rc2 and this was fixed in the 5.0.0 release (that's one of the two 
> fixes that were made after RC2.) ... you'll have to wait for a new MS4W 
> with the release version of MapServer 5.0.0 to test this with AGG, but 
> you can already test it with GD with RC2. I heard that Jeff was working 
> on a new MS4W release yesterday, so it should be available very soon.
> 
> Daniel
> 
> 
> Guillaume Sueur wrote:
>> I think AGG optimization only applies on vector data. Am I wrong ?
>> 
>> Guillaume
>> 
>> Pål Kristensen a écrit :
>>> Hi!
>>>
>>> I have recently installed ms4w 2.2.6 beta which include MS 5.0 RC2. The
>>> reason for this was to test the new AGG rendering engine when using
>>> Mapserver as a WMS server, with only high resolution (RGB) rasters as
>>> the
>>> data source. Most WMS servers around (both free and commercial) uses 
>>> nearest
>>> neighbor interpolation on the resulting image that is transfered to the
>>> client. In situations where the source data is only hires rasters or 
>>> imagery
>>> (as in my case), the quality of the output would be much better if you 
>>> could
>>> apply an bilinear interpolation to the produced image (see the attached
>>> images for an example). Because in most cases the pixels in the source 
>>> data
>>> and the pixels on the screen do not match up, even if I have produces
>>> pyramids on the source data (using gdal gdaladdo with the average option
>>> sett). The only WMS servers that has the ability to interpolate the
>>> resulting image with bilinear interpolation (that I have discovered) 
>>> is the
>>> ESRI ArcIMS ArcMap image service and the ESRI ArcGIS Server.
>>>
>>> I kind of hoped that the new AGG rendering back-end would give an 
>>> option to
>>> set the interpolation method used in the output, but I see no difference
>>> when using AGG instead of GD. (IMAGEMODE is 24bit (RGB) PNG in both 
>>> cases).
>>> Am I missing something here, or do not AGG increase the image quality 
>>> if the
>>> resulting image if the data source is only rasters? Does anyone have any
>>> experience concerning this issue, and maybe could give me some advice?
>>>
>>> ArcGIS Server
>>> http://www.nabble.com/file/p12754990/ArcGIS_Server.png
>>>
>>> Mapserver 5.0 rc2 with AGG rendering
>>> http://www.nabble.com/file/p12754990/MapServer_5rc2_AGG.png
>>> Regards,
>>> Pål Kristensen
>>> Norwegian Mapping and Cadastre Authority
>> 
>> 
> 
> 
> -- 
> Daniel Morissette
> http://www.mapgears.com/
> 
> 

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