Hey Frederik, Frederik Ramm schrieb: > What you're doing is you request an EPSG4326 projected bitmap from the > server but with a height that doesn't fit. Example: Assume your JOSM map > view is 500x500 pixels and you're viewing an area around 60°N in > spherical Mercator. The area displayed is 5° wide. How high is it? The > answer is that it will be about 10° high (let us assume it's 55° to > 65°). You now send a WMS request for an area of 5° by 10° in EPSG4326 > with a width parameter of 500 pixels; normally the image produced would > be 1000 pixels high, but you request a 500 pixel high image, causing the > WMS server to scale (scale! not reproject) the image.
Ok. > Having said that, the effect is less pronounced if you're nearer the > equator, and if you are zoomed in far then the error is way smaller than > typical GPS accuracy errors. Which means ± 15 Meter without WAAS/EGNOS or dGPS. > The proper thing for JOSM would be to add the SRS parameter based on the > current projection, and evaluate a GetCapabilities response before it > even allows you to make a WMS request with the current projection. > (Landsat, for example, will always return EPSG4326 no matter what you > request.) Yes, the server needs to support other projections. Perhaps it would be a better solution to reproject files in JOSM? That would cover all "EPSG:4336"-only servers. Best regards, Tobias _______________________________________________ josm-dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/josm-dev
