Hi Bratliff. The UK OS Projection is like one wide UTM zone. Both UTM and UK OS are Transverse Mercator though with slightly different parameter values. There is no reason why the same techniques can not be used to reproject similar scale UTM tiles onto Google tiles. You could no doubt re-project UTM tiles from more than one 6 degree UTM zone on to one Google map, provided you know which zone the source tile is on. Of course, the technique relies on the source and transformed tiles being of similar scales (meters per pixel).
As you say, the advantage of re-projecting tiles is that we can use the Google API to draw markers, polys, routes, heat maps ... Of course any grid lines on the reprojected tiles end up not being screen north aligned and there is a degradation in text/symbol rendering quality with interpolation. This is what lead me to try a custom projection for the UK tiles. Sadly though we can draw markers on a custom projection map we can't do anything with polys (and so I assume routes). Google have not responded in any way (PM or forum) about vector rendering being broke for non Google projections. I have posted the issue as a bug - star it if you like. I expect that the performance of per tile affine transformations (whether source tile or target tile) will probably outperform any per pixel or small pixel group translations. Its possible that CANVAS may be a better solution than SVG for the non IE browsers - I've not played with it that much yet. If someone wants to port what I have done in SVG to CANVAS for a performance comparison then that is fine by me. Per pixel (or pixel group) will of course be the only way for tiles that cover a large portion of the earth - try zooming my OS demos right out and you will see that things eventually degrade. The solutions I have presented should be good for IE >= 6 , and the in use versions of the other main stream browsers. I don't believe that CANVAS is supported in IE until the new MSIE9. -- You received this message because you are subscribed to the Google Groups "Google Maps JavaScript API v3" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-maps-js-api-v3?hl=en.
