Trajectory Plot Review for TrueView 3DIS (TruNav)

Requires an LP360 EVO Explorer or LP360 Drone license.

Applies to Cycles acquired using a TrueView 3DIS with a TruNav POS, such as a TrueView 1TN or a TrueView 641.

Once the sensor Trajectory Processing has completed, you will be prompted to view the Post Process Trajectory Plot . Select Yes to view the plot, or No to move to the next step. You may reopen the plot for a Cycle at any time by selecting Post Process Trajectory Plot on the Sensor tab of the ribbon. There are several plots that one should review to ensure a viable trajectory solution before moving on to additional processing steps:

Prerequisites

• TruNav trajectory processing completed with POS solution generated.
• Access to:
  • Post Process Trajectory Plot  
  • Base and rover RINEX files.
    • Base files found in: \Project\Area\Cycle\Survey
    • Rover file, "recording.obs", found in: \Project\Area\Cycle\POS
  • TruNav POS file.
    • "recording.pos", found in: \Project\Area\Cycle\POS

Steps to Review Trajectory Data

1. Verify RINEX Inputs

The process involves validating the base and rover RINEX files to ensure accuracy before processing TruNav data.

• Press Trajectory Plot .
• Opens RTKPlot.
• For each base observation file and the rover observation file:
  • File -> Open Obs data -> Browse for the base or rover observation (RNX or OBS).
  • File -> Open Nav data -> Browse for the companion navigation file (BRD*.RNX).
  • Confirm that both base station and rover RINEX files are complete and cover the entire mission duration.
  • Review SatVis, NSat, and SNR/MP plots
  • Check:
    • Observation intervals match expected logging rates.
    • No significant gaps, missing epochs, or cycle slips.
    • Correct antenna metadata in header for base observation files.
  • Close the plot.

Learn more about checking for gaps in base station observation files. 

2. Load POS Solution in RTKPlot

The process involves analyzing the resulting POS solution to ensure accuracy before processing TruNav data.

• Select the desire Active Cycle for review.
• Press Trajectory Plot  
• Loads RTKPlot with the POS file that was generated during sensor Trajectory Processing .

3. Visualize Trajectory

• Use RTKPlot to display:
  • Position scatter plots (horizontal and vertical).
    • Gnd Trk
  • Time-series graphs for latitude, longitude, and height.
    • Position
    • Velocity
    • Accel
    • NSat
• Look for:
  • Smooth trajectory without abrupt jumps.
  • Consistent height profile relative to mission terrain.

4. Check Solution Quality

• Review solution status indicators:
  • FIX (1), FLOAT (2), or SINGLE (5).
    Learn more about GNSS Quality Levels
  • High FIX ratio indicates reliable RTK solution.
• Inspect residuals and standard deviations for anomalies.

5. Validate Base-Rover Geometry

• Confirm baseline length and geometry are within expected limits.
• Large deviations may indicate incorrect base coordinates or poor satellite geometry.

Learn how to use the Base Range Indicator in Survey Nail Manager

6. Export and Document Findings

• Save plots and quality metrics.
• Document:
  • Percentage of FIX solutions.
  • Any observed gaps or inconsistencies.
  • Recommendations for reprocessing if needed.

Best Practices

• Always cross-check base station coordinates against known control points.
• Use consistent time zones and formats across RINEX and POS files.
• If significant FLOAT or SINGLE solutions persist, consider:
  • Increasing observation duration.
  • Improving satellite visibility or base station placement.