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Tiled Map Connector

by Technical Evangelist on ‎09-09-2015 04:08 AM - edited on ‎04-07-2017 08:10 AM by Technical Evangelist (1,800 Views)

1. Slippy Tiles

1.1. Tiles Overview

The map tiles are square bitmap graphics displayed in a grid arrangement to show a map. The Slippy Tiles mechanism is in fact Intergraph's implementation of Slippy Map, a term referring to modern web maps which let you zoom and pan around (the map slips around when you drag the mouse).

In fact the same mechanism is used in the OGC WMTS (Web Map Tile Service) and tiled view of OGC WMS (Web Map Service), which allow consuming map data delivered by raster tiles and presenting it in a map window. Similar approach is used while composing the map for Google Maps and Bing Maps.


1.2. OpenStreetMap

OpenStreetMap is the project that creates and distributes free geographic data. The OpenStreetMap service delivers the maps in tiles that can be handled in the Geospatial Portal thanks to the SlippyTiles project, which incorporates the custom connector for OSM.



1.3. ViaEuropa

ViaEuropa is an online service from Europa Technologies for the delivery of digital maps. The service renders map tiles delivered to the client application and simple SlippyTiles project introducing custom connector to the Geospatial Portal core solutions gives an opportunity to handle it.



2. Implementation

2.1. Map Service

The Slippy Tiles Map Service is an abstract class introducing the necessary common internals for the tiled map services (OSM and viaEuropa) such as single legend definition and coordinate reference system specification (in this case it is EPSG:3785 CRS).




The particular OSM Map Service is a SlippyTilesMapService implementation that incorporates custom mapType property which is dedicated to handle the different available Open Street Map Renderers.


The viaEuropa Map Service introduces the UserId property which is necessary to gain access to the Europa Technologies data. The registration on the viaEuropa page is an obligatory to grant you access to the viaEuropa Open service.


The relevant UserId granted on the registration process shall be provided in the Web.config file. The ViaEuropaUserId<code> key shall be put in the <code>;appSettings><code> section.


   <add key="ViaEuropaUserId" value="granted_id" />



2.2. Map Service Config Provider

The OSM Map Service Config Provider shows explicitly how to pass the introduced mapType property to the client side (JS) by setting (and checking) the Map Service Config. In the similar way is set the Config for viaEuropa Map Service.



2.3. Map Layer

The Slippy Tiles Map Layer introduces the necessary common properties for the map layers of the tiled map services (OSM and viaEuropa) such as tile size, hadled CRS and bounding box. It should be treated as an abstract class.


The actual layer implementations (OSMLayer and ViaEuropaLayer) are responsible for preparing the appropriate requests to the map service and they provide the concrete implementation of get_slippyTileUrl and get_zoomLevelsRange methods.



2.4. Map Types

The new type of data used in the custom Map Service may be easily introduced as the OsmMapType mentioned previously. It is used as a Map Layer setting responsible for switching between different OSM renderings.