Background

Raster Manager is able to open rasters stored on a server by using raster streaming technologies. With the increase of Internet usage and bandwidth, it's feasible to stream raster data fast enough so it can be visualized in MicroStation with the same results as if the raster data is stored locally. 

WMS

WMS stands for Web Map Server and is a standard developed by OGC (Open Geospatial Consortium) for accessing maps from a server. So aside from basic raster data, a WMS server can also provide vector data representing different features such as roads, hydrography, and so forth.  The vector data is not transmitted as is, but is rasterized by the WMS server before being sent to the receiving application.

Creating a WMS raster

The first step for accessing data from a WMS server is to create a .xWMS file, which is an .xml file containing information about the WMS server URL and the map data that should be accessed from this server.

The .xWMS file can be created or edited with an XML editor but it is recommended to use the WMS Map Editor dialog provided by Raster Manager.

• Server URL: The URL for the WMS server for which a connection should be created.
• Available Layers: The list of layers that is available on the WMS server.
• Map Layers: The list of selected layers from the list of available layers that will compose the map to display in MicroStation.
• Server Information: Information on the WMS server that is defined by the server URL.
• Map Range Limits: Describes the method and limit definition to be used to define the bounding box of the layer to be requested to the WMS server.
• Coordinate System: Defines the coordinate system of the data provide by the WMS server. Most WMS servers have the capability to send maps in different coordinate systems. By default, the WMS Map Editor dialog will try to pick the coordinate system which matches the coordinate system of the current model, if any.
• Selected Layer: Displays information about the layer selected in Map Layers (see 3) pane. 

Displaying a WMS raster

Once the .xWMS file has been created with the WMS Map Editor it can be attached like any other raster file. Note that the .xWMS doesn't contain the raster data but simply the connection information to the WMS server and the list of layers that is composing the WMS map.

One particularity of a WMS raster is that it does not have a fixed number of resolutions.  Instead it has an unlimited number of resolutions which are defined by the bounding box (Map Range Limit) requested in world coordinates and the number of pixels requested in for a particular bounding box.

When displaying a WMS raster in MicroStation,  it's possible that the the following image is repeated over the entire displayable area.

This occurs when the WMS server isn't able to send the raster data which may be caused by the following reasons:

1. The server is not online and/or is not working.
2. There is no data at the resolution requested. For example, when the view is zoomed down to the centimeter or millimeter level and no data exists for this accuracy.

ECWP

Raster Manager is able to open images using the ECWP (Enhanced Compression Wavelet Protocol) which is based provides image data on demand from compressed ECW or JPEG 2000 image files.  To open and access a raster using this method,  just enter the ECWP URL in the Open ECWP dialog shown below.

Image Server

Raster Manager can also access rasters remotely using Bentley's Geospatial Web Publishing technology. To open a raster using Bentley's Image Server, you must first define a connection to the server by using the dialog shown below.

• Alias: The alias that should be used to represent the connection. This is the alias that will be shown.
• Name (DNS): The domain name or IP address describing the location of the server. Note that it is important to specify the port number that the image server is listening to at the end of the name, as shown above.

See also

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