[OpenLayers-Users] pixel units to lat/lon units & nexrad

[Christopher Schmidt]

On Wed, Jun 04, 2008 at 09:55:40AM -0700, Scott Baker wrote:
> I was trying to do something similar to this when I first started - I 
> asked here in the list about it too - but received no response. So I 
> spent 3 months figuring it out myself... Correct me if I'm wrong, but I 
> couldn't find any way to use gdal2tiles for anything other then a single 
> map - always in pixel coordinates and not suitable for any sort of 
> overlays.

I think I responded to that claim from another user here:

 http://www.nabble.com/GDAL2Tiles-td16458672.html

 http://openlayers.org/pipermail/users/2008-April/005362.html 

> It's a great method for creating a standalone OL viewer of a raster map 
> but that's about it.

I would tend to disagree.

> As soon as you want to get into mixing layers, overlaying stuff - etc... 
> you will need a mapserver to do it.

This is definitely not true -- even if you can't use gdal2tiles, you
could always write another tool that did something similar. 

> I ended up with mapserver running and then implementing tilecache 
> (mapserver is incredibly slow directly) 

I doubt this is true. It is more likely that your data is poorly
prepared for serving dynamically. (Properly preparing data for dynamic
serving is hard. For vector data, it requires intelligent cartographic
decisions. For Raster data, it requires effort to be put into ensuring
that your data is properly overlay-ed, tiled, not-compressed, etc.) 

> then an OL display. The 
> combination of the three is the only way I found to get nice looking 
> maps and have floexibility enough to include raster, vector, and public 
> data in OL.

Sure, but that's not related to the question at hand. gdal2tiles can't
draw vector data into tiles, so you'll need to set up a server for that
part of it.

Regards,
-- 
Christopher Schmidt
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