[OSM-dev] New tiling code

[Christopher Schmidt]

On Wed, Jun 28, 2006 at 04:55:54PM +0100, Tom Carden wrote:
> On 28/06/06, Christopher Schmidt <crschmidt at crschmidt.net> wrote:
> >Currently, the OpenStreetMap tile.js code does not round its values.
> 
> Isn't that what the _clamp/_quant/scale calculations are doing, or
> have I misunderstood?

Yes, there is rounding there, but there is more math (to convert to
Mercator) afterwards. So you get URLs like:

http://tile.openstreetmap.org/ruby/wmsmod.rbx?WIDTH=256&HEIGHT=128&BBOX=-0.032958,51.49052395477268,-0.021972000000000002,51.49394401031767&zoom=14&landsat=1

> Can anyone suggest a way we can check whether the cache is being used
> properly or not?

If it's not, the site falls over? :)

I zoomed into the Milleinum dome, at zoom level 14, then started
dragging the map around and looking at tiles -- you could probably watch 
LiveHTTPHeaders in Firefox and get a similar result without copy pasting
URLs until one breaks.

This is probably a relatively minor fix -- it probably only happens when
values get small (zooms get high) but it does have an effect at the
higher zoom levels -- the reason I knew about this fix is because we've
done the same thing in OpenLayers.Layer.WMS.

-- 
Christopher Schmidt
Web Developer