[Talk-GB] OS OpenData StreetView Tiles now available

TimSC mapping at sheerman-chase.org.uk
Wed Apr 7 12:53:51 BST 2010

Hi all,

The "very simple WMS that someone wrote in PHP" was written by me. No 
wonder it is a bit dodgy! :) The drop in resolution is due to JOSM 
requesting tiles at the current screen resolution (I think), so the 
tiles are resized by the server when the WMS response is created. I am 
guessing this is where the problem lies - the resizing entails 
resampling the tile. The thing is JOSM does not know what the native 
resolution of the tile, which would result in a higher quality result. 
Probably the best idea is to write another plugin to grab tiles directly 
from the server as potlatch does. This would transfer the required 
resizing from the server to the client.

In both the edgemaster's and Richard's tiles there are periodic kinks 
(about 1 pixel in size) in what should be straight lines. It is more 
obvious in Richard's tiles because they are less noisy. Any idea what is 
causing that?



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