Example data set: Reach precision GPS



Do the following to process and validate a 3D map georeferenced with Reach GPS data.

About the data

  • 112 photos acquired with a Tuffwing UAV Mapper, Reach GPS, Tuffwing Reach integration cable.
  • Sony Nex 5T with Sony 16mm lens.
  • Altitude: 100m.
  • Average Ground Sampling Distance (GSD) 2.82 cm / 1.11
  • Area Covered 0.1139 km2 / 11.3916 ha / 0.044 sq. mi. / 28.1638 acres.
  • Camera triggered by a Pixhawk.
  • No communication between the Reach and Pixhawk. It just goes along for the ride and collects picture locations.
  • Picture locations corrected after the flight using RTKLIB.
  • Here's the Pix4D Quality Report.

Create a New Project in Pix4D

  1. Download the data (507 MB). Contents:
    • Images: 112
    • Geotag file: Geotag.Flight1b.txt
    • Ground Control Point file: GCP.txt

  2. Create a new 3D Map project and add the photos.
  3. Select From File > File Format > L,L,A.
  4. Brows to Geotag.Flight1b.txt and press the OK button.

  5. Select Custom Geolocation Accuracy.
  6. Right click in the Acuracy Horz [m] box and change the value to .05. Do the same for Vert [m].
  7. Click OK.
  8. Process the 3D Map.

Import the GCP file

You can validate the accuracy of the 3D map using the included ground control point file.

  1. Set the GCP coordinate system
  2. Go to Project > GCP/MTP Manager. Select Edit > Advanced Coordinate Options > From List >>then select WGS 84

  3. Import the GCP file.
  4. Select Import GCPs. Browse to GCP.txt.
  5. Change Type from 3D GCP to Check Point.
  6. Press OK.

Mark the Check Points in the rayCloud editor

  1. Select a Check Point from the Tie Points list.
  2. Click on the center of the square target in the Images box. Repeat on 6 photos.
  3. Click the Apply button.
  4. So the same for all Check Points.
  5. Select Process > Rematch and Reoptimize.
  6. Select Generate Quality Report.