Digital Twin Viewer - Map Layers Widget


This article describes the May Layers widget of the Digital Twin module.

The Map Layers widget allows managing the display of the Base Layer and ArcGIS, WMS, and WMTS layers.

Referencing GIS data to the iModel essentially publishes it as raster layers in the view. Use any GIS server (ESRI, open source MapServer, GeoServer, etc.) to compose your map. Then, simply add new connections to the service, through the Map Layers widget and access your GIS data.

Supported Coordinate systems

The Map Layers widget supports two coordinate systems. Make sure the GIS Data to attach is published in one of the following coordinate systems.

When adding a layer, a validation is made on the GIS data coordinate system. If the coordinate system is not supported, the attachment will fail.

Benefits

One of the main benefits of referencing is that the existing complex symbology defined in a GIS system, is automatically accessible, without the need of recreating it.

Another major advantage is accessing live data. This way, the information that is displayed in the Digital Twin viewer is always true and up to date.

This option has some limitations. For example, it is not possible to select an element in the view and see the properties attached to it, unless the server is configured to support non-graphical query operations. If the server is configured in that way and the “Locatable” option is turned ON in the settings panel, it will be possible to over the cursor on a tile and the associated properties will be displayed in a tooltip.

Base layer

Essentially, a Base layer shows geographic information displayed in the background. It provides context for additional layers that overlay on top of the base layer.

The Base layer is available if and only if the iModel is georeferenced. If the

iModel will be displayed with the background color defined in the viewer presentation options and an information message displayed in the Map Layers widget.

The following Bing services are available in the list:

These layers above are present in the list as default, out of the box. The user doesn’t have to add them manually.

The visibility of the layer can be changed by toggling ON and OFF.

The transparency of the Base Layer can be modified by using the slider bar.

Background and Overlay layers

The user can add layers in the Background section and/or Overlay section. Users can drag a layer from one section to the other, as well as order the layers within a section.

Background section – The layers added to this section will be displayed over the Bing layer but behind the iModel.

Overlay section – The layers added to this section will be displayed on top of all layers, including the iModel.

More Options on the layers

Click on the “More” menu at the right-hand side of the layer name to see more options to apply to the layer.

   

Zoom to layer

Selecting the “Zoom to layer” option fits the selected layer in the view.

Detach

Selecting the “Detach” option removes the selected layer from the view.

Transparency slider

Moving the slider changes the transparency of the selected layer. The transparency is applied on the layer once the data button is released.

Add new layer

To add a new layer, click on the “Add Layer” button or on the “+” sign.

Attach New Layer dialog

Type

Select the type of service. The Background and Overlay sections allow referencing three types of GIS data:

 Name

Type a name. Use a name that is relevant so that any user who wants to attach the layer can easily know which layer he is attaching.

 URL

Type or copy the URL of the server to attach.

Here are some examples of URLs that should be used:

Reorder the layers

 

You can move the layers from the background section to the overlay section, and vis versa, by using the drag and drop functionality. The layers can also be reorder within a section, the same way.

 

Delete a layer

 

It is possible to delete layers from the list simply by clicking on the “delete” icon.

 

Turning OFF all layers

 

All the layers from the Map Layers dialog, including the Base layer, can be turned ON and OFF by clicking on the toggle on the upper right side of the dialog.

 

Settings dialog

Different settings are available in the Map Layers Settings panel.

 

Transparency

Use the slider to apply transparency on all layers from the Map Layers widget.

Locatable

Toggle ON this option to see the information and coordinates of the location pointed by the cursor on the Bing layer.

Mask by Models

Toggle ON this option to mask the map layers contained in the view. The iModel and the reality data serve as a clipping element. This can be useful when the iModel contains elements located under the ground. Enabling the mask allows one to see the underground portion of an iModel. When turned off, the map layers block the view.

Elevation Offset (m)

Use this option to adjust the Map layer's elevation to align with the iModel whenever necessary.

Allow Model Under Map

Use this option to allow the display of the underground section of the iModel under the map layers.

By default, the map layers are displayed in the background, completely behind the iModel and reality data, so that the user sees the model in its entirety, even the parts that should be displayed under the ground. 

Terrain

The Terrain section contains options related to the display of the Cesium terrain layer.

Toggle ON the "Enable" option to activate the Cesium terrain layer and have a 3D view of the terrain surrounding the area of the iModel.

Model Height (m)

Use this option to adjust the terrain elevation so that it fits the model elevation.

Apply Elevation Correction

Sometimes the iModel is not displayed at the right elevation in Design Review. Most of the time this happens when the input design file was created with the wrong vertical datum; Ellipsoid instead of Geoid. So when the user turns ON the Cesium terrain, the elevation is incorrect. Another case is when the user has drawn his design at the right location but on a random elevation.
To correct the elevation

Exaggeration 

Use this option to exaggerate the elevation of the Cesium terrain.