Hello OpenLayers Users, We plan to use OpenLayers for a project that requires accurate positioning of overlay objects drawn on an overlay layer above the map layer. We plan to use an updated base map layer such as one of the GSHHS tile sets.
One of the stakeholders in this project has asked me to determine how accurate OpenLayers will be for this purpose. In other words, if the user draws a rectangle that precisely bounds the Isle of Wight with our product, how far off is it likely to be in the real world? Is the coincidence between map layers uniform? The first time I tried to answer this question, I responded in terms of the map layer's accuracy. It was pointed out to me that this is not the full answer. It doesn't matter how accurate the map layer is, if the points that I have selected on my overlay layer are off in relation to the map. I have read several postings here that relate to how OpenLayers handles map projections, and see that it uses Proj.4 to perform its geospatial math. Unfortunately, I don't know enough yet to ask the right question, or where to look in the code. Has anyone come across this issue already? I would like to verify that OpenLayers handles the intersections between the map layer and layers above well enough for our needs, so that we can move forward to implementation. Kind thanks for any pointers! Scott C. Cary, NC USA -- View this message in context: http://n2.nabble.com/Positional-Accuracy-of-Drawn-Overlays-tp4910847p4910847.html Sent from the OpenLayers Users mailing list archive at Nabble.com. _______________________________________________ Users mailing list Users@openlayers.org http://openlayers.org/mailman/listinfo/users