Base Map in EPSG:2056 projection

[Heinrich Baur]

I can display the "Base Map" Vector Tiles with Openlayers and the following Vanilla Code:

// Mapbox layer definitions
// ------------------------

var baseMapSource = new ol.source.VectorTile({
  format: new ol.format.MVT(),
  url: 'https://vectortiles.geo.admin.ch/tiles/ch.swisstopo.base.vt/v1.0.0/{z}/{x}/{y}.pbf',
});

var baseMapLayer = new ol.layer.VectorTile({
    id: "base-map-layer",
    source: baseMapSource,
});

var view = new ol.View({
  projection: "EPSG:3857",
  center: [922300, 5902000],
  zoom: 10,
});

var map = new ol.Map({
  target: "map",
  layers: [baseMapLayer],
  controls: [],
  view: view
});

olms.apply(map, 'https://vectortiles.geo.admin.ch/styles/ch.swisstopo.basemap.vt/style.json');

Is it possible to get the Vector Tiles in projection EPSG:2056 instead of EPSG:3857 and if yes, Is there an example script or what should I change in my script?

Thanks and best regards, Heiri

[Heinrich Baur]

There is another issue: Waters are labeled with incomprehensible character strings (see attached screenshot). Is there a problem in the file "style.json"?

Cheers, Heiri

[Heinrich Baur]

Addendum: The labeling issue only exists with Microsoft Edge. Firefox labels correctly (see screenshot).

Sorry, Heiri

[Heinrich Baur]

The labeling issue is solved when I specify the character set in the HTML file:

    <meta charset="UTF-8">

But I am still interested in any hint about Mapbox Vector Tiles in EPSG:2056 projection

Best regards, Heiri

[Pascal Barth]

Hi Heiri,

We haven't yet officially added VectorTiles to our map viewer, but there's some work-in-progress done here if you want to have a glimpse on how we will achieve it.

To summarize what we do :

We load everything in LV95 with OpenLayers (as it is currently done) and add the VectorTile layer with the help of MapLibre and a bridge component found here

We edited this bridge-component to be able to transform our LV95 zoom level into Mercator zoom on-the-fly, we hope to be able to add this change in the bridge-component itself in the future.

TL;DR;

We show VectorTiles with MapLibre in Mercator

We add that to OpenLayers that runs in LV95, and transform position/zoom on-the-fly to sync MapLibre

Hope it helps, don't hesitate if you want more details on something.

Cheers,

Pascal

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[Heinrich Baur]

Hi Pascal,

Thank you very much for the link to your interesting work on the integration of Mapbox Vector Tiles into web-mapviewer. As you say, it is "work-in-progress": panning and zooming is not yet as smooth as in the swisstopo Android app. WMTS and MVT layers do not always match perfectly (see "Wanderwege" in BaseMap_web-mapviewer.jpg).

I am currently trying a different approach: I am using two separate ol.map objects named mapMVT and map respectively. Two separate <div>s are the targets of the two map objects. One of the <div>s is completely covering the other. The two map objects have different views named viewMercator and viewLV95 respectively. As the names suggest the views use "EPSG:3857" and "EPSG:2056" respectively. I am applying the olms.js bridge to the mapMVT with web-mercator projection:

olms.apply(mapMVT, 'https://vectortiles.geo.admin.ch/styles/ch.swisstopo.basemap.vt/style.json');

In order to match the two maps I am synchronizing the view centers and resolutions of the maps. To synchronize the centers I convert the LV95 coordinates to WGS84 lon/lat coordinates and from there to web-mercator coordinates. To adjust the resolution I am using the following code:

var MVTperLV95resolution = 1/Math.cos(Math.PI * lat / 180);
viewMercator.setResolution(viewLV95.getResolution()*MVTperLV95resolution);

This works but speeds of panning and zooming are comparable to speeds with your approach. MVT and WMTS layers again do not match perfectly (see BasMap_GPS_Schweiz.jpg).

In contrast "ch.swisstopo.swisstlm3d-wanderwege" is matching perfectly with "ch.swisstopo.pixelkarte-farbe" (see Pixelkarte_GPS_Schweiz.jpg). 

Also the match is perfect in the swisstopo Android app (see BaseMap_swisstopo_app.jpg). Presumably this app is not based on Openlayers, do you know what framework they use?

I have two additional questions about the swisstopo implementations of the "basemap" and the "basemap-winter":

1. The API documentation about Mapbox Vector Tiles (api3.geo.admin.ch) does not list an example of an URL to get one pbf tile for the "basemap-winter". My guess "https://vectortiles.geo.admin.ch/tiles/ch.swisstopo.base-winter.vt/v1.0.0/7/67/44.pbf" is not working. Is there a correct URL for "basemap-winter"?
2. The Edge developer console reports the following error:
   olms.js:1
   Expected value to be of type number, but found string instead.
   evaluate @ olms.js:1
   on execution of the following line:
   olms.apply(mapMVT, 'https://vectortiles.geo.admin.ch/styles/ch.swisstopo.basemap.vt/style.json');
   Is there an error in the style.json file?
   

Cheers, Heiri