[OpenLayers-Users] General question and GML question

[Ken Sanderson]

Just thought I would post a quick update. I have been beating my head 
against the problem for a few days and tried most everything I could 
think of including the steps outlined below to reproject the vector 
data. I tried KML as well and though it would display fine in Google 
Earth, it wouldnt display at all in OpenLayers.

Eventually I converted the data in ArcGIS to Web Mercator, then used 
gvSIG to export the GML and that worked perfect. So clearly it was a 
projection issue, but I am not sure why the reproject did not work as it 
seems fairly straight forward to implement. Is there anything I am doing 
wrong here:

// create Google Mercator layers
var gphy = new OpenLayers.Layer.Google( "Google Physical", {type: 
G_PHYSICAL_MAP,'sphericalMercator': true});
var gmap = new OpenLayers.Layer.Google( "Google Streets", 
{'sphericalMercator': true});
var gsat = new OpenLayers.Layer.Google( "Google Sattelite", {type: 
G_SATELLITE_MAP, 'sphericalMercator': true});
var ghyb = new OpenLayers.Layer.Google( "Google Hybrid", {type: 
G_HYBRID_MAP, 'sphericalMercator': true});

map.addLayers([gphy, gmap, gsat, ghyb]);

var partners = new OpenLayers.Layer.GML("Partner Boundaries", 
"data/member_gvsig.gml", {projection: new 
OpenLayers.Projection("EPSG:2153")});

map.addLayer(partners);


Chris I tried to send you my GML files on Friday, was having email 
issues so not sure that you go them or not?

Thanks for your help,

Ken




Christopher Schmidt wrote:
> On Fri, Dec 05, 2008 at 11:42:30AM -0400, Ken Sanderson wrote:
>> Hi everyone, this is about my third time giving OpenLayers a try and 
>> this time I thought I would bite the bullet and ask some questions 
>> instead of just going back to my mapserver setup.
>>
>> First a general best approach question. What I want to do is use google 
>> data and put a simple polygon boundary on top. That boundary is 
>> currently in a shape file. My thinking was to convert the shp file to 
>> gml and just add it as a layer. I have since read that this maybe 
>> tricker then I thought as google data is in a mercator projection that 
>> does not have an EPSG code. 
> 
> OpenLayers has a built in ability to convert between EPSG:4326 (lat/lon)
> and Google's Mercator projection: see
> http://docs.openlayers.org/spherical_mercator/#reprojecting-vector-data
> for more information on how to use it.
> 
>> Second more specific to the use of GML layers. I converted my shp file 
>> to GML using gvSIG and in another attempt shp2gml from spatial order. I 
>> cannot get my GML file to be viewable. Thinking it might be a projection 
>> issue I thought I would just display my GML file on its own, to avoid 
>> any conflicting projections, but that hasnt worked either. Using the 
>> gml-layer.html example I tried to work backwards and put my GML file in 
>> there, no luck.
> 
> Can you share the GML file you generated? It's possible this is a
> version problem, or some other parsing error: without seeing the GML
> file (or a sample file that fails) it's hard to know for sure.
> 
> Regards,

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