[OpenLayers-Users] Non-terrestrial datum [proj4] and ScaleLine

[a.lucas at geolnet.net]

Hello,

here is the full code I wrote.
I have some images for the background and a vector layer I can display over
the base map.


Thanks for any help.

<script type="text/javascript">

Proj4js.defs["PLANETB"] = "+proj=eqc +a=4500000 +b=4500000 +units=m
+no_defs";

var map, vectors, formats;
var graticuleCtl1, graticuleCtl2;


function init(){

map = new OpenLayers.Map('map', { controls: [ new
OpenLayers.Control.Navigation(), new OpenLayers.Control.PanZoomBar(),new
OpenLayers.Control.ScaleLine({bottomOutUnits: '',geodesic: true}), new
OpenLayers.Control.MousePosition(), new OpenLayers.Control.Graticule()
],
projection: new OpenLayers.Projection("PLANETB")
});
var ls = new OpenLayers.Control.LayerSwitcher()
map.addControl(ls);ls.maximizeControl();
var iss = new OpenLayers.Layer.Image( 'ISS (Base 3)', 'Data/ISS.gif', new
OpenLayers.Bounds(-180, -90, 180, 90), new OpenLayers.Size(800,
400),{numZoomLevels: 4});
var topo = new OpenLayers.Layer.Image( 'Topography
(Splined)','Data/spline.png',new OpenLayers.Bounds(-180, -90, 180,
90),new OpenLayers.Size(800, 400),{numZoomLevels:1});


var blank = new OpenLayers.Layer.Image( 'Blank (No Base Map)', '', new
OpenLayers.Bounds(-180, -90, 180, 90), new OpenLayers.Size(800,
400),{numZoomLevels: 4});




var blue_unit = new OpenLayers.Layer.Vector("Blue Unit", { protocol: new
OpenLayers.Protocol.HTTP({ url: "Data/blue_unit.gml", format: new
OpenLayers.Format.GML() }), strategies: [new
OpenLayers.Strategy.Fixed()],visibility: true,//wrapDateLine:
true,style: {fillColor: "#0066cc",fillOpacity:0.4 , strokeWidth: 1,
strokeColor:
"#0066cc", strokeOpacity: 1 }, projection: map.displayProjection, });



map.addLayers([blank, topo,iss,vims,sar,rad,dark_unit,blue_unit,dunes]);

map.zoomToMaxExtent();
var options = { hover: true, onSelect: serialize };  updateFormats();
map.setCenter(new OpenLayers.LonLat(0, 0), 1); }





</script>




On Mon, Jul 8, 2013 at 3:40 PM, Andreas Hocevar <ahocevar at opengeo.org>wrote:

> Hey,
>
> are you sure that your map actually uses the 'PLANETB' projection? Show a
> bit more code, especially which layers you add, or preferably point us to a
> fully configured example. Note that the base layer's projection - if
> specified - overrides the map projection.
>
> Andreas.
>
>
> On Mon, Jul 8, 2013 at 2:51 PM, a.lucas at geolnet.net <a.lucas at geolnet.net>wrote:
>
>> Hello Folks,
>>
>> I already asked but got no reply, so I repost my question, sorry for
>> spamming you on that.
>>
>>
>>
>>
>> I intend to use OpenLayers for an educational project dealing with
>> planetary data.
>> I tried to get an accurate scale bar (i.e., ScaleLine object) from a
>> custom projection but it seems that ScaleLine does not understand
>> non-terrestrial sphere/ellipsoid.
>>
>> Here is what I have done:
>>
>> I first call proj4js:
>> <script src="
>> http://svn.osgeo.org/metacrs/proj4js/trunk/lib/proj4js-compressed.js
>> "></script>
>> then OpenLayers
>>
>> and in a javascript sequence I do this:
>>
>> Proj4js.defs["PLANETB"] = "+proj=eqc +a=4500000 +b=4500000 +units=m
>> +no_defs";
>>
>>       function init(){
>>
>>                map = new OpenLayers.Map('map', {
>>                     controls: [
>>                         new OpenLayers.Control.Navigation(),
>>                         new OpenLayers.Control.PanZoomBar(),
>>                         new OpenLayers.Control.ScaleLine({bottomOutUnits:
>> '',geodesic: true}),
>>                         new OpenLayers.Control.MousePosition(),
>>                         new OpenLayers.Control.Graticule()
>>                     ],
>>                     projection:  new OpenLayers.Projection("PLANETB")
>>                 });
>>
>> Unfortunately, when displaying the page, the scale bar is totally wrong.
>> I played with different values of "a" and "b", ScaleLine does NOT take into
>> account these values. The Proj4 syntax seems correct as it works smoothly
>> under QGIS for instance. For me, OpenLayers just does not understand
>> correctly proj4 projection.
>>
>> Any idea if OpenLayer can really understand proj4 syntax? and if not,
>> how can I contribute (i.e., where, which files?) in order to get this right?
>>
>>
>> thank you for any feedback/ideas
>>
>> _______________________________________________
>> Users mailing list
>> Users at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/openlayers-users
>>
>>
>
>
> --
> Andreas Hocevar
> OpenGeo - http://opengeo.org/
> Expert service straight from the developers.
>
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