On Mon, Oct 18, 2010 at 8:36 AM, David Fawcett <[email protected]> wrote: > Puneet, > > I know that you are using php and not Python,
Thanks David, but I am not using either PHP or Python. I am a Perl guy through and through. Never used anything else. But, that is not really relevant here. I guess what I am looking for is access the to polygon that I just drew using the measure control. Obviously, it has been drawn on the map by OL. Surely it must be accessible somehow. I just can't figure out how. Looking at the GeoJSON example, it seems that if I have a GeoJSON object, I can create a poly out of it. So, putting the two together, it seems natural that if I could save my drawn poly as GeoJSON, I could draw it back out again at a later time. > but you may want to look > at FeatureServer http://featureserver.org/. Aiiiiiieeeee.. not another technology. I haven't looked at featureserver, so I know nothing about it. But my first, gut reaction is that I don't want to implement another technology. I am very happy with the mix of stuff I have going. > > David. > > On Mon, Oct 18, 2010 at 7:50 AM, P Kishor <[email protected]> wrote: >> On Mon, Oct 18, 2010 at 7:35 AM, Richard Greenwood >> <[email protected]> wrote: >>> On Sun, Oct 17, 2010 at 7:17 PM, P Kishor <[email protected]> wrote: >>>> I have created a control after the "OpenLayers Measure Example" >>>> [http://openlayers.org/dev/examples/measure.html], and all is good. >>>> The user can draw a poly in the browser, and measure the area. Now, I >>>> want to save the drawn polygon on the server-side, so I can recreate >>>> it later. I guess if I could convert the drawn poly to a geojson >>>> object, I could save it on the server. Then, at the click of a button, >>>> the saved map extent and the drawn feature could be recreated. Any >>>> ideas how I could do this? >>> >>> Puneet, >>> >>> I send the object to a PHP script on the server and save it into a >>> PostGIS database. >> >> Right, but what is the call for getting the object from the OL client? >> I guess I should simplify my question by breaking it up into two parts >> -- >> >> 1. Once I have drawn a poly on the map (using the measure control), >> how do I get its geometry that I can then send to the server? All I >> need to know here is the appropriate method that will give me the >> geometry of the poly I drew. >> >> 2. What all are the essential params required to reconstruct the state >> of a map view in OL? I guess I need to know the layers that are >> visible, and the map extent that needs to be saved. In my use case, >> since I also want to reconstruct the poly that was drawn, I need that >> geometry. The last I can get via #1 above, but how do I get the >> "current" map extent and the names of the layers that are currently >> visible? Is there a method that can "dump" all the information >> required to reconstruct the current state? >> >>> I don't use GeoJSON or any standard format, but >>> probably should. >> >> What format do you use? >> >>> Do a POST not a GET as geometries can become quite >>> big. And I always do an ST_ISVALID() before inserting it. If you're >>> working with polygons it is not uncommon for the user to draw an >>> invalid poly and there is nothing to stop that poly from being >>> inserted. It is only when you query that invalid poly that the >>> problems begin. If you're only working w/ lines and points then it's >>> not a worry. >>> >>> Similarly, I query a PHP script for an object's extent using the >>> PostGIS ST_EXTENT() function, and pass that to OpenLayers. ST_EXTENT() >>> is an aggregate function, so you can pass a set of records and get the >>> bounding box of the whole set, e.g. if you had a bunch of address >>> points: >>> SELECT ST_EXTENT(wkb_geometry) WHERE zipcode='83014'; >>> Would return the bounding box of the whole set of matching points. >>> >>> In both cases (saving and retrieving) I'm using home grown AJAX calls >>> to home grown PHP scripts. I'm sure others will suggest WFS-T which >>> has it's strengths, but forces you into WFS. I'm doing everything with >>> native MapServer layers. >> >> Simple is better. I am sticking to WMS with MapServer. For geographic >> data I have a mix of shapefiles, images, and PostGIS. For everything >> else, I am using SQLite (for now). >> >> Its all working quite well. >> >>> >>> Regards, >>> Rich >>> >>> >>>> -- >>>> Puneet Kishor http://www.punkish.org >>>> Carbon Model http://carbonmodel.org >>>> Charter Member, Open Source Geospatial Foundation http://www.osgeo.org >>>> Science Commons Fellow, http://sciencecommons.org/about/whoweare/kishor >>>> Nelson Institute, UW-Madison http://www.nelson.wisc.edu >>>> ----------------------------------------------------------------------- >>>> Assertions are politics; backing up assertions with evidence is science >>>> ======================================================================= >>>> _______________________________________________ >>>> Users mailing list >>>> [email protected] >>>> http://lists.osgeo.org/mailman/listinfo/openlayers-users >>>> >>> >>> >>> >>> -- >>> Richard Greenwood >>> [email protected] >>> www.greenwoodmap.com >>> >> >> >> >> -- >> Puneet Kishor http://www.punkish.org >> Carbon Model http://carbonmodel.org >> Charter Member, Open Source Geospatial Foundation http://www.osgeo.org >> Science Commons Fellow, http://sciencecommons.org/about/whoweare/kishor >> Nelson Institute, UW-Madison http://www.nelson.wisc.edu >> ----------------------------------------------------------------------- >> Assertions are politics; backing up assertions with evidence is science >> ======================================================================= >> _______________________________________________ >> Users mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/openlayers-users >> > -- Puneet Kishor http://www.punkish.org Carbon Model http://carbonmodel.org Charter Member, Open Source Geospatial Foundation http://www.osgeo.org Science Commons Fellow, http://sciencecommons.org/about/whoweare/kishor Nelson Institute, UW-Madison http://www.nelson.wisc.edu ----------------------------------------------------------------------- Assertions are politics; backing up assertions with evidence is science ======================================================================= _______________________________________________ Users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/openlayers-users
