Map Suite WebAPI Edition supports many popular GIS file formats. Data is contained in layers. In this learning sample, we will go over the concept of a layer and explain how they are used to make a map. The different types of layers will be discussed.

A layer is a visual representation of geospatial data. You can think of layers much like actual terrain in the real world. The bare earth might be a layer and have either physically defined boundaries, such as a fence around a military installation, or legal boundaries, such as the border of a country. Another layer on top of that might be roads that are built upon the bare earth. It is important to understand this when working with layers, as they need to be added in the logical order you might expect so that they can be visualized correctly from above. In other words, you would not want to lay down roads and then cover them with earth, because they could not be seen or used by vehicles.

There are three types of layers that are supported by all editions of Map Suite: Vector, Raster, and Web-Based. Vector data contains points, lines, and polygons and is useful for storing data that has discrete boundaries, such as country borders, land parcels, and streets. Raster data contains a matrix of pixels and is used for digital images like aerial imagery, floor plans, or topographic maps. Web-based data comes in a variety of forms. It could be basemaps served by Google or Bing. Or it could be near-real-time information like NOAA weather data. Check out the Map Suite Data Format Guide to see all the formats that are supported by Map Suite.

In this learning sample, there is an example of each of these types of layers:

Vector

• Shapefile
• TAB
• TinyGeo
• FileGeoDatabase
• SQLite
• WKB
• KML
• MapShape
• InMemoryFeature

Raster

• MrSID
• JPEG2000
• GeoTIFF
• BMP/PNG/GIS/JPG/Tiff

Web Service

• NOAA Radar
• NOAA Weather Station
• WMS

There is also a customized layer that contains custom vector data to demonstrate that it is possible to create a layer from any type of data.

In order to better control layers and assist with caching, layers may be grouped into overlays. All layers in an overlay will generate one bitmap. The caching happens at the overlay level where the bitmap is generated.

Make sure to order the layers so that they are drawn appropriately. The order of the layers will determine what is visible, as the layers sit on top of one another. Think about the order in the real world. On the bottom, put the area-based terrain layers, such as land and water. Next, put features like roads that sit on top of the terrain. Finally, put points of interest, or POIs, on top of the physical features.

There are two projects in the Visual Studio solution. One is for the Leaflet javascript mapping library and one is for OpenLayers. In each project, the LayersController contains the functions that load each of the layer types. Each function is prefaced with the type of layer. At the bottom is InitializeProjection, which sets up the map projection, and DrawTileImage, which draws the Layer Overlay bitmap. The App_Data folder contains data for each of the layer types.