I'm trying to access ArcGis server map cache from Openlayers. I've seen the threads on mailing list about this topic, yet I'm still having the following issue: the cached images are only aligned correctly for some of the map zoom levels. So, my map has 10 zoom levels. The cached tiles align correctly for levels 1-4, do not align correctly for levels 5-7, and align correctly for levels 8-10. I tried to implement following posted fix for changing the extent at different zoom levels, but I dont know where to get the value for this.ymin variable. Also, it's been stated that the maxExtent should be perfect fit for tiles; but is there a standard equation to use to calculate this perfect fit for ArcGis map cache? Any help would be greatly appreciated. Dave
matthewsnape wrote: > > I have been using a previous version of the code extensively and can > confirm that it works. We certainly had trouble with the extents issue. > I found that the extents had to be different for each zoom level. I used > the following code to calculate the correct extents, added to the start of > the geturl and setmap functions: > > var res = this.map.getResolution(); > var tile_height = res*512; > var yorigin = this.maxExtent.top; > var ydiff = yorigin-this.ymin; > var tilecount = ydiff/tile_height; > var tilecountr = Math.ceil(tilecount); > var coverage = tilecountr*tile_height; > var yminorigin = yorigin-coverage; > this.maxExtent.bottom = yminorigin; > > Because you need a fixed number of tiles to cover the map, the bottom tile > will overlap the edge of the map extents. At different resolutions the > amount of overlap changes. This code calculates the y co-ordinate of the > bottom of the map extents, depending on your resolution. It uses an > addittional attribute "ymin" to store the minimum y value of the data > extents, allowing maxExtent.bottom to change as appropriate. > > > > -- View this message in context: http://www.nabble.com/ArcGIS-server-9.2-support-for-OL-tp9691195p18595695.html Sent from the OpenLayers Dev mailing list archive at Nabble.com. _______________________________________________ Dev mailing list [email protected] http://openlayers.org/mailman/listinfo/dev
