[gdal-dev] ECW Format

Frank Warmerdam warmerdam at p...
Mon Apr 2 14:13:35 EDT 2001


Tyler Mitchell wrote:
> 
> Hi Frank,
> I am very interested in a windows build on openev with this functionality.
> Particularly interested in using it for some 3d viewing if possible.
> Currenltly I am uncompressing/converting to JPEG.
> Now ECW is pretty neat because it only display what you can see at a
> particular scale - how do you account for this in gdal and/or openev. As
> you zoom in you should see more detail right?

Tyler, 

Right. 

OpenEV has a concept of asking files (via GDAL) for reduced resolution
overviews when displaying at overview levels, and then if the user zooms
in, each of the tiles is updated with full resolution imagery as time
permits. 

In most file formats extracting overviews is only efficient if extra overview
levels have been built. In the case of ECW the overviews can (apparently)
be extracted especially efficiently because of the nature of wavelets. 

I will try to prepare a new OpenEV distribution sometime this week. Bug
me Friday if you haven't heard anything more. 

Best regards,

---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, warmerdam at p...
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent




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