True View 3DIS Field Data Checking Methods

Field operations can be expensive and often have time limitations due to limited access, weather, or even specific temporal ranges specified by a client. For these reasons you should always perform field data checks of 3DIS production datasets to the best of your ability. It is usually more efficient to fly another a survey immediately rather than reschedule. If you have a problem you cannot diagnose GeoCue support will take in-field support calls during normal business hours, or respond to a summitted ticket with 4 business hours. These steps are ordered by both importance and required time. Steps 1-7 are relatively quick and can give you reasonable assurance you are leaving the field with good data. Steps 8-10 require internet but will give you complete assurance you have a good dataset.

  1. Controller Box Codes and Messages: Pay close attention to your controller box lights and the LCD read-out messages during initialization and wind down. Refer to our controller box codes table in the hardware guide for the specific meaning of messages. Upon landing be especially aware of a red LED for the GNSS light indicating a comprise of your GNSS quality. Also be aware if any step in the initialization or wind down processes stall at a certain step or take an excessive amount of time. If you experience any behavior you cannot diagnose from the the controller box table contact GeoCue support.

  2. Cycle Logs: (Skippable if using Step 7) After wind down insert the UMS into your computer. Navigate to the \Cycle_YYMMDD_hhmmss\System folder and open the CycleLog.csv in a text editor (Notepad ++ is a freeware application with color coding for good readability). Search the file (Control+F) for WARNING, ERROR, and FAIL these entries will be serious errors that may comprise your data, contact GeoCue support if you are not sure how to troubleshoot these errors.
    You can also create a batch file that will search and print WARNING, ERROR, and FAIL messages. Paste the below code into a text file and save it as CycleLogChecker.bat, then drag-and-drop the CycleLog.csv onto the batch file, a console window will appear and it will print out line containing WARNING, ERROR, or FAIL if they exist.

    findstr /I /N “Fail Warning Error” %1
    Pause

    If you would like the batch to output the error messages to another file use:

    findstr /I /N “Fail Warning Error” %1 > CycleLogErrors.csv
    Pause
  3. Image Count: (Skippable if using Step 7) Open the folders for Cycle_YYMMDD_hhmmss/Flight_YYMMDD_hhmmss/Camera1 and Camera2 and count the number images. While inside a folder in Windows Explorer the file count will be displayed in the lower left corner. The image counts between Camera1 and Camera2 should match by no more than 2-3 images. If there is a large discrepancy you experienced camera errors.
  4. Image Quality: You can spot check photos for each camera to ensure photos are not blurry or overexposed. Blurry photos can happen during low altitude flights, slowing down your speed from 5 m/s to 4 m/s or even lower may eliminate blurring. The shutter speed can also be manually set in the CoreConfiguration.json file, refer to the TrueView manual for more details on manually setting camera parameters.
  5. Lidar data size: Inspect the folder Cycle_YYMMDD_hhmmss/Flight_YYMMDD_hhmmss/Laser1 there should be a a large file named laser.bin for most typical flights it should be over 1GB. If the file is small or even zero you have an error with your Lidar sensor.
  6. TVDataChecker.exe: (True View 410 only) This utility will scan the file for time interval gaps or spin reversals. The TVDataChecker can be obtained through your client FTP account. It will also produce a log file in the Laser1 folder. GeoCue may request this file if you notice and errors with your laser.bin
  7. Import Cycle to True View EVO: (If you have a roaming license or internet connectivity) The import process for True View EVO will, by its nature, check certain elements of your dataset while it imports them. The most obvious error would be if you flight plan does not match how you programmed it in your flight controller software which may indicate a heartbeat timing error with your system. If you encounter import error you cannot diagnose contact GeoCue support.
  8. Post-process your trajectories with POSPac: (If you have internet connectivity) Review the POSPac_Report.pdf Inspect the graph on page 4 for cycle slips, inspect page 23 for at or near 100% fixed rate as well as generally consistent satellite count on the graph. Page 38 Position Error RMS should be within horizontal and vertical tolerances of your sensor and not have any large spikes indicating a loss of accuracy.
  9. Inspect a Point Cloud Profile: (If you completed the POSPac post processing successfully) Geocode your point cloud then draw a profile over a uniform surface such as a roof top, parking lot or a flat well maintained paved road. Change the coloring to Point Source ID inspect for flight line misalignment or excessive point cloud noise.
  10. QC checkpoint Z values: A final assurance that your point cloud is correct is to inspect the Z value statistics for your check points. Your RMSE should not exceed the rating for your sensor. If you have a large RMSE with a closely matching Mean Error you likely have a bias which is typically caused by improper pole heights with survey equipment, mismatches with geoids, or incorrect lever arm offsets. If you have a large error range first ensure that your check points were not obstructed during survey, if so turn off compromised check points. If a large error range still remains the other common occurrence is that you had a GNSS quality is during the flight or your sensor did not download the correct calibration, or there is a malfunction with your sensor and the calibration is no longer valid.

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