Image offset from LiDAR Data

PIX4Dmapper
1

Hi!
I don’t know if there is already someone tried to ask this question/concern/problem.
We have this LiDAR equipment called Riegl VP-1 mounted in a Helicopter, and everytime we process the image data we always do the rectification after the process just to correct the position of image with the LIDAR.
Our LiDAR Data is fix and it matches with the Ground Survey, it just that the image is offset and always need to be rectify.

*Additional info, we have a Base station for our PPK while doing the Aerial Survey.

Actually even in our drone(Matrice 600pro) mounted with Riegl MiniVUX(LiDAR also) still the same.

What could be the problem? Hoping for your response.

Thank you so much in advance!

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@RASA_Surveying just a theory, but if you are getting your image positions from PosPac, are you applying the UNIX vs GPStime stamp offset? I.e the 18 seconds or are your position differences larger than what that would account for?

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Hi Rasa,
Assuming you are not using GCPs, I would first look at what correction your base station is broadcasting. Then you need to make sure your horizontal and vertical coordinate systems are set appropriately in the image properties editor.

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The images we used to process for our orthophoto is base from exported images that had been colorized from pointcloud. so we assume that it will be the same position from the lidar data.

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Can you give me some example sir how to do it?
by the way… for our Base station (PPK Mode) we set it to 1 sec reading time.

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By the way,

Our drone we are currently using for LIDAR are;

  1. DJI M300 w/RTK mounted with L1
  2. DJI M600 mounted with RIEGL MiniVux (PPK Base)

Both drones are having problem with the IMAGE OFFSET and always need to RECTIFY.

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Hi @RASA_Surveying, it’s strange that two independent systems are both seeing a similar image offset, this makes me think it might be a coordinate transformation issue.

Please feel free to email me at jason@geodronesurvey.com with more details including: current workflow, and EPSG codes of coordinate systems you are using for base pos as well as output coordinate system of trajectories from PosPac/DJI Terra and final project coordinates (also including any geoid offsets etc).

Regards,
Jason.

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Hello Sir Jason,

It would be a great help! I’ll send you some sample for your references.

Thank you!