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      How to Determine if Terrain Following is Needed for a LiDAR Survey

      Understanding your site conditions prior to flying a LiDAR survey, and planning your mission accordingly is critical to ensuring your project goals are met.

      Introduction

      In this guide, we will walk through the process of deciding if terrain following is necessary for your LiDAR survey. Using a tool like Google Earth, you can make an informed decision to ensure you obtain the necessary LiDAR dataset and meet your project goals.  

      Steps to Determine Terrain Following Needs

      1. Open Google Earth: Start by opening Google Earth and zooming into your area of interest.
      2. Draw a Path: Use the line path measurement tool to draw the rough coverage of your survey area.  If your survey area is a large, you may need to create multiple line paths to understand the full topographic character of your site.  
      3. Check Elevation Profile: Right-click on the path and select "Show Elevation Profile." This will display the elevation changes along your path.
      4. Analyze Elevation Changes: If your elevation profile shows significant variation, such as the 32 meters drop in the video above, you will need terrain following if your end goal is survey grade accuracy.

      Example Scenario

      Imagine you are surveying a construction site for a new roadway. Here's a step-by-step example from the above video:

      1. Draw Path in Google Earth: Click to draw the path of the potential roadway.
      2. View Elevation Profile: Observe the elevation changes. In our case, the elevation ranges from 1779 meters to 1808 meters.
      3. Calculate Flight Height: If you set your flight height to 45 meters above the central elevation (1793 meters), the flight height will vary significantly across the survey area.
      4. Adjust for Consistency: To maintain a consistent flight height and ensure survey-grade accuracy, use terrain following.

      Recommendations

      • Each survey site is unique, so always analyze the topographic variation before planning your mission.
      • For sites with topographic variation greater than 8-10 meters, consider incorporating terrain following.

      If you have any questions or need further assistance, please reach out to us at support@rockrobotic.com.