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How to Field Check Ultra LiDAR data without a ROCK Desktop license

When you need to verify a dataset in the field, without a ROCK Desktop license, without your dongle, or without time to process, you can still perform a fast, effective QC by reviewing the raw folder structure generated by your ULTRA unit.

Overview

The goal of this workflow is to confirm that:

  • All expected photos were captured
  • The LiDAR file exists and is an appropriate size
  • IMU and GNSS data were recorded consistently
  • No immediate signs of data corruption are present  

1. Confirm Folder Structure

After copying data from the USB drive, verify the dataset contains:

  • CAM1
  • Lidar1
  • POS
  • device_info.json

If any of these are missing, perform further investigation before leaving the field.

2. Check Photo Count (CAM1 Folder)

  1. Open the CAM1 folder.
  2. Review the total item count.
  3. Identify the first image (should end in _1.jpg).
  4. Scroll to the last image—confirm numbering is sequential.

You should find:

  • Total image count (minus temp files) matches final image number
  • No missing frames or numbering gaps

Optional check:
 Open the .tmp file in a text editor (e.g., Notepad++).

  • Scroll to the bottom
    Final line number should match the final image number

3. Check the LiDAR File (Lidar1 Folder)

For Ultra:

  • Expect a single .epr file
  • File size should be multiple gigabytes
  • Longer flights = larger files

A very small MLR/EPR file (e.g., 1–2 GB on a long flight) may indicate incomplete transfer or a capture issue.

4. Check GNSS & IMU Files (POS Folder)

For R3 / R3 Pro, you should see:

  • ...imu.imr
  • ...imu.ins
  • ...gnss.gps

Verify:

  • ...imu.imr and ...gnss.gps files are roughly the same size
  • Minor variance is normal
  • Major variance (e.g., GNSS file half the size of IMU files) suggests GNSS signal loss or data corruption
  • ...imu.ins will be about 2x larger - this is expected

5. When to Re-Fly or Investigate Further

Re-fly or investigate if you notice:

  • Missing/partial photo sequences
  • Very small epr files
  • POS files with major size mismatches
  • Folder structure missing key components
  • Any unexpected file size anomalies

Example Quick-Check Workflow (OL)

  1. Copy dataset from USB to laptop.
  2. Verify folder structure is complete.
  3. Count images and confirm numbering is sequential.
  4. Verify LiDAR file exists and is multiple gigabytes.
  5. Compare IMU/GNSS file sizes.
  6. Document anomalies or proceed confidently.

Need Help?

If you’d like ROCK to review your dataset or walk you through quick field checks, contact:

support@rockrobotic.com