Mobile Mapping Trajectory

This page describes how to use the desktop mobile mapping extension “Trajectory”.

The “Trajectory” (previously “Trajectory Adjustment”) extension makes it possible to apply measured ground control points to correct a well defined segment of your mobile mapping run to improve its absolute accuracy.

Main Toolbar > Extensions > Trajectory Adjustment

A well defined segment of a run can be adjusted or removed. An adjustment is calculated using all available measured ground control points. Removing or adjusting segments will affect all resources. A quick preview can be processed, but to actual adjustment of the entire run requires consolidation.

• A segment is well defined continuous section of the run's trajectory. There are no limitation on the number of segments in one run, segments cannot overlap each other.
• All available mobile mapping resources will be adjusted or removed : trajectory, image positions, image files and point cloud data. Processed point cloud ortho images are not adjusted.
• Ground control points are measured and managed by run, see Mobile Mapping Ground Control Points.
  All measured ground control points within the segment range will be used for calculating the adjustment.
• A quick preview of the adjustment for the opened segment only can be pre-processed. This will not correct or remove data of the run. All corrections (adjustments, remove segments and remove point cloud points) will be applied on “Consolidation”, see Mobile Mapping Consolidation.

On adjusting a segment using the trajectory adjustment extension the relevant snapshot of the ground control points dataset will be saved and used for future processing. Any measured ground control point within 10 meter (xyz) to the trajectory segment will be retained.

To use the “Trajectory” extension following conditions are required :

• Timestamps, all mobile mapping resources must have the same timestamps reference.
• Trajectory
• Run version 3, available from Orbit version 11.0, see Orbit Run Versions & Structure

Following color codes are used to indicate the segment status :

• Purple : opened segment The opened segment appears as purple line on map and withing the mobile mapping 3D point cloud view.
• Red : segment to be removed
• Blue : segment to be adjusted
• Grey / Orange : adjustment not yet defined

File menu drop-down
Create a new segment, open, and close or delete the opened segment via the file menu drop-down icon.

• To create a new segment a run must be opened.
• Segments are automatically numbered and stored within the run directory.
• Only one segment can be opened at once.

Select on map
Define segment start and end point on the Map 2D.
On clicking this button the according map function will be activated. Two clicks along the trajectory will define start and end point. Once one end point is known a temporary red segment indication will appear when hovering above the run trajectory. When the other segment end is defined the “Select on map” function will be deactivated.
On defining the segment on map the map 2D zoom and context menu function retain available, see MapCanvas

Select in graph

Restarting the selection of an existing segment will replace this segment and remove all processed preview data.

Length and GCP's

The segment length (meters) and the number of measured ground control points within the segment are displayed (measured GCP's relevant for segment / total number of GCP's in run)

Once the opened segment is defined you can decided to “Adjust” or “Remove” the segment.
The options “Process Preview”, “Adjustment in” and “Adjustment Out” are only relevant when you “Adjust” the segment.

• Process Preview : Flag to process the adjustment preview. The time required to process the preview depends on the size of the run and the length of the segment.
• Adjustment In/Out : Define which correction needs to be applied to the adjustment of the start of the segment to the first measure GCP (Adjustment In) and the last measured GCP to the end of the segment (Adjustment Out).
  Choose “Extend” to keep the shift that was measured in the corresponding GCP (First GCP for “Adjustment In”, last GCP for “Adjustment Out”).
  Choose “None” to fade out the shift to the start or the end of the segment.

Only if the “Process Preview” option is checked the image and point cloud point segment count will calculated and displayed below the progress bar.

Analyze gaps of data within trajectory segments.

• Flag the data content to be analyzed when scanning:
  • Scan Photo Positions
  • Scan Point Cloud
• Set minimum time and distance

• Show Original data / Show Adjusted data : Switch the displayed mobile mapping resources. Adjusted data can only be displayed if the preview has been processed.

• Show Adjusted trajectory

• Changes only : Display the segment only, either the original or adjusted segment mobile mapping resources.
• Highlight changes : Highlight the segment's point cloud, only possible if the preview has been processed.

• Show all segments on Map 2D

Graph
(Click on image to enlarge)
Navigation:

• Zoom: Scroll in and out to zoom into the graph. The graph will zoom to the cursor.
• Slider: Use the slider to move the graph on the Time scale.
• Cursor: The cursor position is always visible:
  • On the map: When moving the cursor on the trajectory graph a little black line will appear on the map on the according position
  • On the trajectory graph: When moving the cursor over the trajectory on the map, a black line will appear on the trajectory graph on the according position.

GCP's
Flag GCP's to display the Mobile Mapping Ground Control Points on the trajectory graph.

• The GCP's are displayed as a grey line on the graph.
  
• Measured Ground Control Points appear in blue.
  
• Single click on the GCP-line on the graph to focus on the map.
  
• Double click on the GCP-line on the graph to focus on the map and in the mobile mapping tab.

Hit points

Select segment
Click the “Select” button to select a segment on the graph:

1. Click and drag (from left to right) on the graph to select a segment
   1. The new segment will be added to the sidebar with following number = last segment number + 1.
2. Click “Confirm”
3. Continue trajectory adjustment in sidebar.

The Trajectory Adjustment extension integrates seamless with the Map component :

• Hovering above the Graph will indicate the according trajectory time stamp as black line on Map.
• Double click anywhere on the Graph will center the Map 2D to the focused trajectory time stamp.
• Hovering above the trajectory on Map will indicate the according snapped trajectory time stamp as black line on Map and Graph.
• Right click while hovering above the trajectory on Map to center Trajectory Graph to the focused trajectory map position.