====== Vector Overlays on Mobile Mapping Views ======

This pages describes how to overlay / display vector datasets in Orbit desktop mobile mapping views.

Any 2D or 3D [[180:technology:supported_formats:index|supported vector resource]] can be overlayed on mobile mapping images or 3D point cloud view. Images and raster resources cannot be overlayed. To overlay a dataset special attention is required to the dataset coordinate reference system, structure definition and legend.

===== How to overlay =====

{{orbitgis:entrance_icon_2.png?nolink&25  |}}  [[180:desktop:dataset:index|Dataset List]] >  [[180:desktop:dataset:index|Dataset Context Menu]] > Display in Mobile Mapping \\ Dataset List > Dataset Indicators > [[180:desktop:dataset:operations_indicators#use_in_extension|Extension Indicator]]

The dataset doesn't need to be visible on the map to be overlayed in the mobile mapping views. 

===== Overlay preferences =====

{{  mobile_mapping:desktop:core:use:vector_overlay_window_1110.png?nolink|}}

{{orbitgis:how_to_find.png?25&nolink |}} Tabs > Mobile Mapping > Opened View > [[180:desktop_ext:mobile_mapping:use:toolbars|1st View Side Toolbar]] > Measure icon

  * Transparency : slider to set the transparency of overlayed objects. 
  * View Depth : slider to set the maximum distance to display objects referred to the current view point.
  * Vertical Offset : slider to adjust the calculated height of 2D objects.

**View Depth** \\

The vector overlay view depth defines the maximum distance between mobile mapping view point and dataset objects. \\
Once a single object vertex is within the view depth range, the entire object will be overlayed.

The calculation of view depth is slightly different for image and 3D point cloud mobile mapping view :
  * Image view : distance from the overlayed objects to the view position, the image position.
  * 3D point cloud view : distance from the overlayed objects to ground level position of the current 3D view. 

**Vertical Offset**

To display a 2D dataset in a 3D environment, a reference ground Z value is calculated for each 2D object. \\
The vector overlay vertical offset is applied on all objects of 2D datasets only. The Z coordinates of 3D objects will be respected as is. 

The calculation of reference Z is slightly different for image and 3D point cloud mobile mapping view :
  * Image view : Z coordinate of the photo position view point minus the height offset of the camera above ground, see [[180:desktop_ext:mobile_mapping:manage:runs_version|Orbit run configuration]].
  * 3D point cloud view : Z coordinate of the 3D view point downwards intersection with the point cloud. This technique will only be used if no images are available or no image view has been openend.
===== Points of attention =====

=== Dataset coordinate reference system ===

To combine Geo and mobile mapping resources the coordinate reference system of each individual resource must be set. Only if the CRS of each resource is well defined, vector resources can be reprojected on the fly to be displayed on mobile mapping data.

  * CRS of vector datasets, see  [[180:technology:core:crs|]] and [[180:desktop:dataset:general|]].
  * CRS of mobile mapping runs, see [[180:desktop_ext:mobile_mapping:manage_import:templates|]] and [[180:desktop_ext:mobile_mapping:manage_import:index|]]. 

=== Dataset structure ===

To display 2D objects in a 3D environment, a reference ground Z value is calculated. The Z coordinate of 3D objects will be respected as it is. \\
If a 2D dataset is set incorrectly as a 3D dataset, the Z coordinate value (=0) will be respected. Most probably these objects will not be visible because they will displayed far below expected ground level.

Check the the object Z values,see [[180:desktop:tabs:inspector|]], and set the dataset structure accordingly, see [[180:desktop:dataset:contents:index|]].

=== Accuracy ===

Overlays and mobile mapping resources may not match as expected. The accuracy of both needs to be taken into account which may result in an error larger than expected.