I am developing an application that displays land ownership information via OpenLayers. One of the requirements is to be able to select a land parcel using OpenLayers using GetFeatureInfo for further manipulating. The problem I have is that once I zoom down to a scale less than 1:15000, the accuracy of the displayed land parcels goes out in a seemingly random manner.
The link http://souwest.dnsalias.com/instant/pages/test.html shows an example of the problem. It shows a set of land parcels within a certain bounds and has a layer showing a selected land parcel (in this example #15). I am quite sure that the centroid of the land parcel being displayed is correct as shown and that the bounds used to zoom are correct. At the zoom selected by getZoomForExtents in this example, the map seems shifted north and east. If you zoom out once, it then seems shifted south and west. Zooming out more seems to show an accurate projection. The WKT data for the selected land parcel is: MULTIPOLYGON(((28.15951 -32.759207,28.159547 -32.759313,28.159599 -32.759351,28.159321 -32.759625,28.159174 -32.759518,28.159095 -32.759293,28.15951 -32.759207))) The data is stored in Postgis served via GeoServer and the SRS is EPSG:4326. Using Udig or going directly to GeoServer and exporting a png, the map is shown 100% accurately so the problem I am having is only exhibited using OpenLayers. Could anyone perhaps help me to find what I am doing wrong ? This is my first OpenLayers application (in fact, my first geospatial application !) so I know I must be doing something really stupid. I have seen a post on this mailing list about JS rounding errors but the extent of the inaccuracy shown here is far greater than what was suggested in that post. -- View this message in context: http://www.nabble.com/Accuracy-of-OpenLayers-at-scales-less-than-1%3A15000-tp19567946p19567946.html Sent from the OpenLayers Users mailing list archive at Nabble.com. _______________________________________________ Users mailing list [email protected] http://openlayers.org/mailman/listinfo/users
