How to Troubleshoot Issues in Pix4D

Troubleshooting Photogrammetry Issues in Pix4D

Aerotas has processed tens of thousands of drone survey projects for thousands of surveyors and civil engineers. We use a wide range of software applications in our data processing workflow because each project is different. But, Pix4D is usually the first step in that workflow. Aerotas is proudly powered by Pix4D, and that is our photogrammetry software of choice. Many of the firms we work with build this proficiency in-house and process a portion of their data using Pix4D. The most common question we get from surveyors who are doing their own photogrammetry is “what are the best settings in Pix4D?” Unfortunately, there are no best settings. In fact, it is not about the settings, but rather it is about the workflow.

At Aerotas, every project goes through multiple rounds of processing to properly manage camera calibration, ground control, project cohesion, and a host of other things. This article is an overview of common photogrammetry issues, troubleshooting techniques, and recommendations to resolve the issues in order to ensure the best possible accuracy in Pix4D. We will look at camera issues, flight planning & ground control problems, missing data, and processing failures.

The most critical and most often overlooked question that needs to be asked on every drone project is: did something go wrong? The challenge is that unless the photogrammetrist knows what to look for, it can be easy to miss that something went wrong.

The first job of the drone photogrammetrist is to know how to check whether something went wrong. This is also the most significant limitation of purely automated data processing services -- many issues that can seriously compromise the accuracy of a project would not be caught by automated QA methods. We regularly see issues that automated services would not catch.

• Camera

  • Dirty/Damaged Lens

  • Unfocused/Distorted Imagery

  • Gimbal Power Failure

  • Camera Out of Calibration

• Flight Planning

  • Overlap Too Low

  • Overlap Too High

  • Unnecessary Cross-Hatch

  • Flight Altitude Too Low

  • High Relief: Low Overlap at High Elevation

  • Not flown with RTK enabled

• Ground Control

  • Poorly Marked GCPs

  • Low Quantity of GCPs

  • GCP Distribution Suboptimal

  • GCP Showing Error