[OpenLayers-Users] drawing a geojson layer

[Puneet Kishor]

On Sep 23, 2011, at 3:15 PM, Puneet Kishor wrote:

> 
> On Sep 23, 2011, at 3:05 PM, <christopher.schmidt at nokia.com> wrote:
> 
>> Are you using OSM? Did you reproject your coordinates anywhere?
> 
> 
> No, I am using Google Maps base layer. My data are in lat/lng, so I believe this s a re-projection issue.


Yeah, that was it. I transformed my data on the server while extracting it from Pg. It works fine now. On the other hand, if I decided that I'd rather send lng/lat to the client, what would I have to do on the client side? Could I just declare the projection on my layer so that even though I'd be adding lng/lat to it, it would display the features correctly?


> 
> I redefined my map like so
> 
>            map = new OpenLayers.Map("map", {
>                controls: [
>                    new OpenLayers.Control.LayerSwitcher(),
>                    new OpenLayers.Control.MousePosition({div:document.getElementById("coords")})
>                ],
>                projection: new OpenLayers.Projection("EPSG:900913"),
>                displayProjection: new OpenLayers.Projection("EPSG:4326")
>            });
> 
> 
> and then
> 
>            var vector_layer = new OpenLayers.Layer.Vector(
>                "vector layer", 
>                {projection: new OpenLayers.Projection("EPSG:4326")}
>            );
>            map.addLayer(vector_layer);
> 
> and then 
> 
>           var geojson_format = new OpenLayers.Format.GeoJSON();
>           vector_layer.addFeatures(geojson_format.read(featurecollection));
> 
> I am assuming that is not the right way, because that is not working. Do I have to transform every point one by one?
> 
> 
>> 
>> -- Chris
>> 
>> On Sep 23, 2011, at 3:07 PM, ext Puneet Kishor wrote:
>> 
>>> I have a fairly straightforward code like so, with the JSON data coming out of Pg. I am using OL 2.11
>>> 
>>>  var data = {
>>>    "type" : "FeatureCollection"
>>>    "features" : [
>>>       {
>>>          "geometry" : {
>>>             "coordinates" : [[[x1, y1], [x2, y2], [x3, y3]]],
>>>             "type" : "MultiLineString"
>>>          },
>>>          "type" : "Feature",
>>>          "properties" : {"code" : 101, "desc" : "blah" }
>>>       },
>>>       {
>>>          "geometry" : {
>>>             "coordinates" : [[[x1, y1], [x2, y2], [x3, y3]]],
>>>             "type" : "MultiLineString"
>>>          },
>>>          "type" : "Feature",
>>>          "properties" : {"code" : 102, "desc" : "blah" }
>>>       },
>>>       {
>>>          "geometry" : {
>>>             "coordinates" : [[[x1, y1], [x2, y2], [x3, y3]]],
>>>             "type" : "MultiLineString"
>>>          },
>>>          "type" : "Feature",
>>>          "properties" : {"code" : 103, "desc" : "blah" }
>>>       },
>>>    ]
>>>  }
>>> 
>>>  var geojson_format = new OpenLayers.Format.GeoJSON();
>>>  var lyr = new OpenLayers.Layer.Vector("layer name"); 
>>>  PK.vars.map.addLayer(lyr);
>>>  trenches.addFeatures(geojson_format.read(data));
>>> 
>>> Yet, no errors and no features drawn on the map. What am I doing wrong?
>>> 
>>> Puneet._______________________________________________
>>> Users mailing list
>>> Users at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/openlayers-users
>> 
>