[OpenLayers-Users] openlayers + tilecache + resolutions

[Ivan Grcic]

Hi,  i think its something like this:

scale = resolution * OpenLayers.INCHES_PER_UNIT[1m] *OpenLayers.DOTS_PER_INCH

(you can set OpenLayers.DOTS_PER_INCH to some other number but default is 72)

scale = resolution * 39.3700787401575 * 72

resolution = 39.3700787401575 * 72 / scale

You just need to set zoom levels, like 1 000 000, 500 000, 100 000, 10
000...and calculate scales according to them...

Cheers!

On Thu, Jul 10, 2008 at 3:43 PM, Wendell Turner <wendell at enflight.com> wrote:
>
> How does someone compute the resulutions array?  As I
> understand it, to make openlayers work well with tilecache,
> the zoom levels and resolutions all need to match.  Also,
> maxResolution: "auto" is specifically bad for this reason.
>
> Given a mosaic of geotiff images in epsg:3394 (which is in
> meters), and knowing the (outer) bounding box of them, how
> do I compute the resolutions array so that the layers
> generated by tilecache_seed.py match those requested by
> openlayers?
>
> Thanks,
>
> Wendell
>
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-- 
Ivan Grcic

igrcic at gmail.com
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