[OSM-dev] request for hosting of WMS layers

[Jean-Guilhem Cailton]

Jukka Rahkonen a écrit :
> jamesmikedupont <at> googlemail.com <jamesmikedupont <at> googlemail.com> writes:
>
>   
>> Lets see:The russian toplogical maps 24G 
>>     
> ...But they are converted to tiffs so much bigger. 
> I guess we could go back the ECW proprietary compressed jpeg.. 
> but that needs special drivers.
>
> ECW is a fine format but it is a bit unclear if the license allows to use it for
> free on the server side even as an input image. It is probably OK but nobody
> seems to know for sure. What is sure is that it is not allowed to 
> send out ecw from a server without ECW SDK license from Erdas.
>
> If disk space is a problem a rather good alternative is to use jpeg compression
> inside tiff. Mapserver works pretty fast with such tiff images. The command to
> use is like this:
>
> gdal_translate -of GTiff -co COMPRESS=JPEG -co PHOTOMETRIC=YCBCR -co TILED=YES
> -co JPEG_QUALITY=85 input.tif output.tif
>
> However, both ecw and jpeg compression gives some problems if images are warped
> and have nodata areas which are often written out as totally black or white
> pixels. After compression nodata areas are no longer uniformly black and marking
> pixels with RGB value of 0 0 0 as transparent does not work. As a result there
> will be some amount of very dark but not totally black pixels which will remain
> visible. However, this can be avoided by doing some mosaicing and cutting before 
> compression. I can give some advice if needed, but perhaps OSM-dev is not the
> most suitable place for that. 
>
> -Jukka Rahkonen-
>
>
>   
How about free implementations of JPEG 2000 
(http://www.jpeg.org/jpeg2000/), such as JasPer 
(http://gdal.org/frmt_jpeg2000.html, 
http://www.ece.uvic.ca/~mdadams/jasper/) or OpenJPEG 
(http://www.openjpeg.org/) ?

Best regards,

Jean-Guilhem
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