Gaps in distance between photos taken with the Ladybug5+

Answered

Tassio

• November 10, 2023 21:43

Hello, we have a Ladybug5+ system integrated with an Applanix POS LV positioning system. The equipment is operational, but after conducting field surveys and processing the trajectory using PosPAC MMS, and exporting the photos from the .pgr file, we noticed that some GPAs were generated. We are conducting the survey considering a 3m distance between photos; this issue occurs randomly throughout the survey.

Some sample photos:

The trajectory behavior is correct; the photos were taken very close in this manner. We are capturing the photos using the ladybugSimpleRecording SDK script.

Link to the used ladybugSimpleRecording: https://we.tl/t-UcB63XqyII

 

 

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• Official comment

  

  TDY_Demos

  Community team

  • November 15, 2023 21:33

  

  Hello Tassio,

  Our camera does not capture by distance without a hardware trigger.  Typically, the GNSS would send out a trigger signal to the camera via the GPIO.  My understanding is the Applanix model you have does not trigger by distance.

  As such, the only software option is to trigger by distance on the software side, which is not ideal.  The code in ladybugSimpleRecording is meant to show how to do that: images are captured at full framerate, distance between the images is compared, and if the distance is greater than 3m, the image is saved.  Depending on the speed of the car and your framerate, distance between images could be much greater than the 3m, which could explain some possible gaps.

  In your case, it seems there may be gaps in distance but not in images, since it looks like before the gap you have multiple images that are close together.  This seems not like dropped frames, but repeating timestamps/GPS locations and then the coordinates catch up.  This could be based on the data coming straight from the Applanix system, or a timestamp error.

  As this is more complicated and not something for a forum, I will create a support ticket with you and we can try to troubleshoot.  It is best to compare the timestamps of the ladybug stream file and the timestamps/coordinates from the Applanix system and see where the gaps are coming from.

  Thank you,
  Demos
• 

  TDY_Manuel

  Community team

  • November 14, 2023 09:42

  

  Hello Tassio, 
  
  Could we please upload a small stream file that shows the problem?

  Best regards,

  Manuel 

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